Java 8¶

Java 8 Key Features¶

Java 8 introduced several key features that have had a profound impact on the language and its ecosystem. These features include lambda expressions, the Stream API, default and static methods in interfaces, functional interfaces, method references, the new Date and Time API, the Optional class, and enhancements for parallel and concurrent programming. Let's dive into each of these features with easy-to-understand explanations and examples.

Lambda Expressions:¶

Lambda expressions provide a concise way to represent anonymous functions. They allow you to define and pass around blocks of code, making your code more readable and expressive. Here's a simple example:

   // Traditional approach
   Runnable runnable = new Runnable() {
       @Override
       public void run() {
           System.out.println("Hello from a traditional anonymous class!");
       }
   };

   // Using Lambda expression
   Runnable lambdaRunnable = () -> {
       System.out.println("Hello from a lambda expression!");
   };

Stream API:¶

The Stream API allows you to process collections in a functional and more readable way. You can perform operations like filtering, mapping, and reducing on collections with ease. For example:

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
   int sum = numbers.stream()
                   .filter(n -> n % 2 == 0)
                   .mapToInt(Integer::intValue)
                   .sum();

Default and Static Methods in Interfaces:¶

Java 8 introduced the ability to define default and static methods in interfaces, enabling you to add new methods to existing interfaces without breaking implementations.

   interface MyInterface {
       void regularMethod();

       default void defaultMethod() {
           System.out.println("This is a default method.");
       }

       static void staticMethod() {
           System.out.println("This is a static method.");
       }
   }

Functional Interfaces:¶

Functional interfaces have a single abstract method and are essential for working with lambda expressions. Examples include java.util.function.Predicate, Consumer, and Supplier.

Method References:¶

Method references provide a shorthand notation for invoking methods. They come in four forms, including references to static methods and instance methods.

   // Reference to a static method
   Function<String, Integer> parseInt = Integer::parseInt;

   // Reference to an instance method of a particular object
   String str = "Hello";
   Consumer<String> printer = str::println;

New Date and Time API:¶

Java 8 introduced a modern Date and Time API (java.time package) that addresses the shortcomings of the old java.util.Date and java.util.Calendar classes. It provides better support for date and time calculations, formatting, and parsing.

   LocalDate today = LocalDate.now();
   LocalTime now = LocalTime.now();

Optional Class:¶

The Optional class is used to represent an optional value that may or may not be present. It helps prevent NullPointerExceptions by explicitly handling absence of values.

   Optional<String> optionalName = Optional.ofNullable(getName());
   String name = optionalName.orElse("DefaultName");

Parallel and Concurrent Programming Enhancements:¶

Java 8 introduced parallel streams that allow you to leverage multi-core processors for improved performance when processing large datasets in parallel. However, it's essential to use them judiciously.

Nashorn JavaScript Engine:¶

Java 8 includes the Nashorn JavaScript engine, which provides a modern JavaScript runtime environment for Java applications. It allows you to execute JavaScript code within your Java applications, making it easier to work with both languages together.

   ScriptEngineManager manager = new ScriptEngineManager();
   ScriptEngine engine = manager.getEngineByName("javascript");
   engine.eval("print('Hello, Nashorn!')");

Enhanced Collections:¶

Java 8 introduced several enhancements to the Collections framework, including the forEach method for iterating over collections and the removeIf method for removing elements based on a condition.

    List<String> names = new ArrayList<>();
    names.add("Alice");
    names.add("Bob");
    names.add("Charlie");

    // Using forEach
    names.forEach(name -> System.out.println("Hello, " + name));

    // Using removeIf
    names.removeIf(name -> name.length() > 5);

Improved Type Inference:¶

Java 8 improved type inference, making it easier to work with generic classes and methods. You can now omit explicit type declarations in many cases.

    List<String> names = new ArrayList<>();

Repeatable Annotations:¶

Java 8 introduced the ability to apply multiple annotations of the same type to a single element, making it more flexible and expressive for defining metadata.

    @Author("Alice")
    @Author("Bob")
    public class Book {
        // ...
    }

Improved Concurrency with CompletableFuture:¶

Java 8 introduced the CompletableFuture class, which simplifies asynchronous programming and enhances concurrency. It allows you to perform asynchronous tasks, handle exceptions, and compose multiple asynchronous operations.

    CompletableFuture<Integer> future = CompletableFuture.supplyAsync(() -> 42);
    future.thenApply(result -> result * 2)
          .thenAccept(finalResult -> System.out.println("Final result: " + finalResult));

Default Methods for Extending Interfaces:¶

Default methods in interfaces allow you to add new methods to existing interfaces without breaking the implementing classes. This feature promotes backward compatibility while evolving APIs.

    interface MyInterface {
        default void myDefaultMethod() {
            System.out.println("Default method in interface.");
        }
    }

Functional Programming Paradigm:¶

Java 8 encourages functional programming by providing lambda expressions and streams. This paradigm shift allows developers to write more concise and expressive code, which is especially valuable for complex operations on collections and data processing.

    List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
    long count = names.stream()
                     .filter(name -> name.length() > 4)
                     .count();

Simplified Exception Handling with `try-with-resources`:¶

Java 8 introduced the try-with-resources statement for automatic resource management. It simplifies the handling of resources like files and streams by automatically closing them when they are no longer needed.

    try (BufferedReader reader = new BufferedReader(new FileReader("file.txt"))) {
        // Read from the file
    } catch (IOException e) {
        // Handle the exception
    }

Improved Garbage Collection:¶

Java 8 introduced the G1 (Garbage First) garbage collector, which aims to provide better performance and predictability by minimizing pause times and maximizing throughput. This can be especially valuable for applications with large heaps.

New and Enhanced APIs:¶

Java 8 introduced various new and enhanced APIs, including the CompletableFuture API for asynchronous programming, the Spliterator interface for improved iteration over collections, and enhancements to the java.util.concurrent package for better concurrency control.

Improved Security with TLS 1.2:¶

Java 8 introduced support for Transport Layer Security (TLS) 1.2, which is crucial for secure communication over the internet. It enhances the security of Java applications, ensuring that they can establish secure connections with external services and servers.

Method Parameter Reflection:¶

Java 8 introduced the ability to reflectively access method parameter names, which is particularly useful for libraries and frameworks that require runtime access to parameter names for tasks such as validation and documentation generation.

    public void myMethod(@MyAnnotation String name, @MyAnnotation int age) {
        // Access parameter names and annotations reflectively
    }

Enhanced Collections Factory Methods:¶

Java 8 added factory methods to create immutable or unmodifiable collections easily. These methods simplify the process of creating collections and help avoid accidental modifications.

    List<String> immutableList = List.of("Alice", "Bob", "Charlie");
    Set<Integer> unmodifiableSet = Set.copyOf(mySet);

Compact Profiles:¶

Java 8 introduced compact profiles, which are smaller subsets of the Java SE platform. They allow developers to create more compact and optimized runtime environments tailored to the specific needs of their applications, reducing the footprint of Java applications.

Performance Enhancements:¶

Java 8 brought various performance enhancements, including improvements in the JVM (Java Virtual Machine) that resulted in faster execution of Java applications. These enhancements contribute to better overall application performance.

Integration with JavaFX:¶

Java 8 integrated JavaFX as part of the standard library, making it easier to develop modern and interactive user interfaces for desktop applications.

    import javafx.application.Application;
    import javafx.scene.Scene;
    import javafx.scene.control.Button;
    import javafx.stage.Stage;

    public class JavaFXExample extends Application {
        // JavaFX application code
    }

Easier Migration to Later Versions:¶

With the introduction of new features and improved APIs in Java 8, developers are better equipped to migrate their code to later versions of Java, taking advantage of additional enhancements and features introduced in subsequent releases.

Lambda Expressions¶

Lambda expressions in Java 8 are a powerful feature that allows you to represent anonymous functions concisely. They are primarily used to define and pass around blocks of code, making your code more readable and expressive. Lambda expressions enable you to write more compact code when working with functional interfaces. Let's dive into the concept of lambda expressions and provide clear examples to facilitate understanding.

In Java 8, lambda expressions provide a way to define small, reusable blocks of code in a more concise and readable manner. These expressions are particularly useful when working with functional interfaces, which are interfaces that have a single abstract method.

Here's the basic syntax of a lambda expression:

(parameters) -> expression or block of code

Let's break down the components:

Parameters: These are the input parameters (if any) that your lambda expression takes. You can have zero or more parameters. If there's only one parameter and its type is inferred, you can omit the parentheses. For multiple parameters, parentheses are required.
Arrow (->): The arrow separates the parameter list from the expression or block of code. It's the central symbol in a lambda expression.
Expression or Block of Code: This is the code that the lambda expression encapsulates. It can be a single expression or a block of code enclosed in curly braces. If it's a block of code, you must use curly braces, and you may need to include a return statement if the block returns a value.

Let's see some practical examples:

Lambda Expression with No Parameters:

   Runnable runnable = () -> {
       System.out.println("Hello from a lambda expression!");
   };

Lambda Expression with One Parameter:

   (x) -> x * x

In this example, the lambda expression takes one parameter (x) and returns its square.

Lambda Expression with Multiple Parameters:

   (a, b) -> a + b

This lambda expression takes two parameters (a and b) and returns their sum.

Lambda Expression as an Argument:

Lambda expressions are often used as arguments to methods that accept functional interfaces. For example, the forEach method of a List accepts a Consumer functional interface:

   List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
   names.forEach(name -> System.out.println("Hello, " + name));

Here, the lambda expression is used to define what should happen for each element in the list.

Lambda expressions shine when you work with functional interfaces, such as Runnable, Consumer, Predicate, and others from the java.util.function package. They allow you to pass behavior as a parameter, making your code more modular and easier to maintain.

In summary, lambda expressions in Java 8 are a concise way to define and use anonymous functions. They provide a clearer and more expressive way to work with functional interfaces, making your code more readable and flexible.

Capturing Variables in Lambda Expressions¶

Lambda expressions can also capture variables from their enclosing scope, making them extremely flexible. These variables can be either effectively final or final. An effectively final variable is one whose value doesn't change after it's assigned.

Here's an example of capturing variables:

public void calculate(int a, int b) {
    int result = 0; // Local variable
    Operation operation = (x, y) -> {
        result = x + y; // Capturing 'result' from the outer scope
        return result; // Using 'result' in the lambda expression
    };

    int sum = operation.perform(a, b);
    System.out.println("Sum: " + sum);
}

In this example, the lambda expression captures the result variable from the enclosing method's scope. However, you can only capture variables that are effectively final or final.

Method References and Lambda Expressions¶

In addition to lambda expressions, Java 8 introduced method references, which provide a concise way to refer to methods or constructors. Method references are often used in conjunction with lambda expressions.

There are four types of method references:

Reference to a Static Method:

   Function<String, Integer> parseInt = Integer::parseInt;

This example references the parseInt method of the Integer class.

Reference to an Instance Method of a Particular Object:

   String str = "Hello";
   Consumer<String> printer = str::println;

Here, str::println is a reference to the println method of the str object.

Reference to an Instance Method of an Arbitrary Object of a Particular Type:

   List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
   names.forEach(System.out::println);

System.out::println is a reference to the println method of any System.out object.

Reference to a Constructor:

   Supplier<List<String>> listSupplier = ArrayList::new;

This example references the constructor of the ArrayList class.

Method references provide a more concise way to express lambda expressions when you're simply calling a method or constructor, making your code even more readable.

In conclusion, lambda expressions in Java 8 are a game-changer for writing concise and expressive code, especially when working with functional interfaces. They allow you to pass behavior as parameters and capture variables from their enclosing scope. When combined with method references, they offer a powerful toolset for writing clean and efficient code. Understanding and using lambda expressions is a crucial skill for Java developers in the modern programming landscape.

Best Practices¶

While lambda expressions in Java 8 provide a powerful way to write concise and expressive code, it's important to follow best practices to ensure readability and maintainability of your code. Here are some tips:

Use Descriptive Variable Names: When defining lambda parameters, use meaningful and descriptive variable names. This makes it easier for others (and your future self) to understand the code.

   names.forEach(name -> System.out.println("Hello, " + name));

In this example, name is a clear and descriptive variable name.

Keep Lambda Expressions Short: Lambda expressions should be concise and focused on a specific task. If a lambda expression becomes too long or complex, consider refactoring it into a separate method.

   // Avoid long and complex lambda expressions
   names.forEach(name -> {
       if (name.length() > 5) {
           System.out.println("Long name: " + name);
       }
   });

   // Better: Extract the logic into a separate method
   names.stream()
        .filter(name -> isLongName(name))
        .forEach(name -> System.out.println("Long name: " + name));

   // Define a method
   private static boolean isLongName(String name) {
       return name.length() > 5;
   }

Consider Using Method References: When a lambda expression simply calls an existing method or constructor, consider using method references for clarity and brevity.

   // Lambda expression
   Function<String, Integer> parseInt = s -> Integer.parseInt(s);

   // Method reference
   Function<String, Integer> parseInt = Integer::parseInt;

Avoid Capturing Mutable Variables: Be cautious when capturing variables from an outer scope in lambda expressions, especially if those variables are mutable. Changes to mutable captured variables can lead to unexpected behavior.

   int counter = 0;
   Runnable runnable = () -> {
       counter++; // Avoid capturing mutable variables
   };

Use Lambda Expressions with Streams: Lambda expressions work seamlessly with Java streams, allowing you to write functional and declarative code for operations on collections.

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

   // Using lambda expressions with streams
   int sum = numbers.stream()
                   .filter(n -> n % 2 == 0)
                   .mapToInt(Integer::intValue)
                   .sum();

Know Your Functional Interfaces: Familiarize yourself with common functional interfaces from the java.util.function package, such as Consumer, Predicate, Function, etc. Understanding these interfaces will help you choose the appropriate one for your lambda expressions.
Test and Debug: Lambda expressions, like any other code, should be thoroughly tested and debugged. Use unit tests and debugging tools to ensure their correctness.
Document When Necessary: While lambda expressions can make your code more concise, avoid making it cryptic. When a lambda expression's purpose is not immediately obvious, consider adding comments or documentation to clarify its intent.

By following these best practices, you can make the most of lambda expressions in Java 8 while maintaining code readability and reliability. Lambda expressions are a valuable addition to Java's toolbox, enabling more expressive and functional programming styles.

Stream API¶

Java 8 introduced the Stream API, which provides a powerful way to process collections of data. Streams allow you to perform complex data manipulations and transformations in a concise and functional style. In this explanation, we'll dive into what the Stream API is and provide easy-to-understand examples and code snippets.

The Stream API is a significant enhancement in Java 8 for processing collections of data. It's designed to make working with data in collections more efficient and expressive. Streams allow you to perform operations like filtering, mapping, and reducing on collections with ease. Let's explore some key concepts and examples.

Creating a Stream:¶

You can create a Stream from various data sources, including collections, arrays, and even I/O channels. Here's how you can create a Stream from a list of integers:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
Stream<Integer> numberStream = numbers.stream();

Stream Operations:¶

Once you have a Stream, you can perform operations on it. There are two types of operations: intermediate and terminal.

Intermediate Operations:¶

Intermediate operations are operations that transform a Stream into another Stream. Common intermediate operations include filter, map, flatMap, and distinct. For example, let's filter even numbers from our numberStream:

Stream<Integer> evenNumbers = numberStream.filter(n -> n % 2 == 0);

Terminal Operations:¶

Terminal operations produce a result or a side-effect and close the Stream. Common terminal operations include forEach, collect, reduce, and count. For example, let's find the sum of even numbers:

int sum = evenNumbers.reduce(0, (a, b) -> a + b);

Example: Filtering and Collecting:¶

Here's a more complete example. Suppose we have a list of strings representing names and we want to filter out names that start with the letter "A" and collect the result into a new list:

List<String> names = Arrays.asList("Alice", "Bob", "Amy", "David");
List<String> filteredNames = names.stream()
    .filter(name -> !name.startsWith("A"))
    .collect(Collectors.toList());

// filteredNames will contain ["Bob", "David"]

Benefits of Streams:¶

Streams promote a more functional and declarative style of coding, making code more readable.
They enable parallel processing, which can significantly improve performance when working with large datasets.

The Stream API in Java 8 provides a powerful and expressive way to process collections of data. It simplifies complex data manipulations and encourages a more functional programming approach. By understanding how to create and use streams, developers can write cleaner and more efficient code for data processing tasks.

Working with Parallel Streams:¶

One of the standout features of the Stream API is its ability to easily switch between sequential and parallel processing. Parallel streams allow you to leverage multi-core processors for potentially significant performance improvements when dealing with large datasets. You can convert a sequential stream to a parallel stream using the parallel() method:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
Stream<Integer> parallelStream = numbers.parallelStream();

Once you have a parallel stream, the operations you perform on it are automatically parallelized, distributing the work across available processor cores. Be cautious when using parallel streams, though, as parallelism introduces the overhead of thread management, and not all operations benefit from parallel processing.

Stream Example: Mapping and Collecting:¶

Let's take another example where we have a list of employee objects, and we want to extract their names and collect them into a comma-separated string:

class Employee {
    private String name;

    public Employee(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

List<Employee> employees = Arrays.asList(
    new Employee("Alice"),
    new Employee("Bob"),
    new Employee("Carol")
);

String employeeNames = employees.stream()
    .map(Employee::getName)
    .collect(Collectors.joining(", "));

// employeeNames will be "Alice, Bob, Carol"

In this example, the map operation transforms each employee object into their name, and the collect operation joins the names into a single string.

Exception Handling:¶

Streams provide a convenient way to handle exceptions during processing. You can use the forEach method with a lambda that includes exception handling:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
numbers.stream()
    .forEach(number -> {
        try {
            int result = 10 / number;
            System.out.println("Result: " + result);
        } catch (ArithmeticException e) {
            System.err.println("Error: Division by zero");
        }
    });

This code safely handles division by zero errors within the stream.

The Stream API in Java 8 is a versatile tool for processing collections of data. It offers a functional and expressive way to work with data, allowing you to perform various operations seamlessly. Whether you're filtering, mapping, reducing, or working with parallel streams, Java 8's Stream API empowers developers to write cleaner and more efficient code for a wide range of data processing tasks.

Working with Parallel Streams:¶

One of the standout features of the Stream API is its ability to easily switch between sequential and parallel processing. Parallel streams allow you to leverage multi-core processors for potentially significant performance improvements when dealing with large datasets. You can convert a sequential stream to a parallel stream using the parallel() method:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
Stream<Integer> parallelStream = numbers.parallelStream();

Once you have a parallel stream, the operations you perform on it are automatically parallelized, distributing the work across available processor cores. Be cautious when using parallel streams, though, as parallelism introduces the overhead of thread management, and not all operations benefit from parallel processing.

Best Practices:¶

To make the most of the Stream API, consider the following best practices:

Use Method References: Method references, like Employee::getName in the previous example, make your code more concise and readable.
Avoid Stateful Operations: Some stream operations, like sorted(), are stateful and can be inefficient for parallel streams. Be mindful of their use and prefer stateless operations when possible.
Keep Streams Short and Simple: Long chains of operations can become hard to read and debug. Break down complex operations into smaller, more manageable steps.
Parallelize with Caution: Parallel streams can improve performance, but they also introduce complexity and potential thread-safety issues. Use them judiciously and be aware of synchronization requirements.
Immutable Data: It's a good practice to work with immutable data structures when using streams. It simplifies parallelism and reduces the risk of unintended side effects.
Avoid Blocking Operations: If you need to perform blocking operations within a stream, consider using CompletableFuture or other asynchronous mechanisms to prevent blocking the entire stream.
Collectors: Explore the various collectors available in the Collectors class, as they can simplify common collection tasks like grouping, partitioning, and summarizing.
Exception Handling: Handle exceptions appropriately within stream operations to ensure robust error handling, as shown in the previous exception handling example.

Intermediate & Terminal Operations¶

Intermediate Operations are used to perform transformations and filters on the elements of a Stream. They are called intermediate because they can be chained together to form a pipeline of operations. Here are some common Intermediate Operations:

map(Function mapper): This operation applies the provided function to each element of the Stream and returns a new Stream with the results. For example:

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
   List<Integer> squares = numbers.stream()
                                   .map(n -> n * n)
                                   .collect(Collectors.toList());

In this example, map transforms each element by squaring it.

filter(Predicate predicate): This operation filters the elements of the Stream based on the provided predicate and returns a new Stream containing only the elements that satisfy the condition. For example:

   List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");
   List<String> filteredNames = names.stream()
                                     .filter(name -> name.length() > 4)
                                     .collect(Collectors.toList());

Here, filter retains only names with more than four characters.

sorted() or sorted(Comparator comparator): These operations are used to sort the elements of the Stream. The first one sorts the elements in their natural order, while the second allows you to specify a custom comparator. Example:

   List<Integer> numbers = Arrays.asList(5, 3, 1, 4, 2);
   List<Integer> sortedNumbers = numbers.stream()
                                         .sorted()
                                         .collect(Collectors.toList());

This sorts the numbers in ascending order.

distinct(): This operation removes duplicates from the Stream, ensuring that each element is unique. Example:

   List<Integer> numbers = Arrays.asList(1, 2, 2, 3, 3, 4, 5);
   List<Integer> distinctNumbers = numbers.stream()
                                           .distinct()
                                           .collect(Collectors.toList());

Here, distinct eliminates the duplicate values.

Terminal Operations¶

Terminal Operations are the final step in a Stream pipeline, and they produce a result or a side-effect. They trigger the execution of the entire Stream pipeline. Here are some common Terminal Operations:

collect(Collector collector): This operation collects the elements of the Stream into a collection or another data structure. Example:

   List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");
   String concatenatedNames = names.stream()
                                   .collect(Collectors.joining(", "));

This collects the names into a single, comma-separated string.

forEach(Consumer action): This operation performs a specified action for each element in the Stream. Example:

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
   numbers.stream().forEach(n -> System.out.println(n));

It prints each number in the Stream.

count(): This operation returns the number of elements in the Stream. Example:

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
   long count = numbers.stream().count();

count in this case would be 5.

reduce(BinaryOperator accumulator): This operation combines the elements of the Stream using the provided binary operator and returns the result. Example:

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
   int sum = numbers.stream()
                   .reduce((x, y) -> x + y)
                   .orElse(0);

Here, reduce computes the sum of the numbers.

These are the main types of operations in the Stream API in Java 8. Intermediate Operations allow you to transform and filter data in a stream, while Terminal Operations produce a final result or perform side-effects on the data. Understanding these operations is key to effectively using Java 8 Streams for data processing.

Example Demonstrations¶

To make it even clearer, let's dive into more detailed examples of how Intermediate and Terminal Operations work:

Intermediate Operations Examples:¶

Example 1: Using `map` and `filter`¶

Suppose you have a list of words, and you want to create a new list containing the lengths of words that start with the letter 'A':

List<String> words = Arrays.asList("Apple", "Banana", "Avocado", "Cherry", "Apricot");
List<Integer> lengthsOfAWords = words.stream()
                                      .filter(word -> word.startsWith("A"))
                                      .map(String::length)
                                      .collect(Collectors.toList());

In this example, filter is used to select words that start with 'A', and map transforms those words into their lengths. The result is [5, 7, 7].

Example 2: Using `sorted`¶

Let's say you have a list of integers, and you want to sort them in descending order:

List<Integer> numbers = Arrays.asList(5, 3, 1, 4, 2);
List<Integer> sortedDescending = numbers.stream()
                                         .sorted((a, b) -> b.compareTo(a))
                                         .collect(Collectors.toList());

Here, the sorted operation with a custom comparator sorts the numbers in descending order. The result is [5, 4, 3, 2, 1].

Terminal Operations Examples:¶

Example 1: Using `collect`¶

Suppose you have a list of names, and you want to concatenate them into a single comma-separated string:

List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");
String concatenatedNames = names.stream()
                               .collect(Collectors.joining(", "));

After applying the collect operation, concatenatedNames will contain "Alice, Bob, Charlie, David".

Example 2: Using `forEach`¶

If you have a list of numbers and you want to print each number squared:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
numbers.stream().forEach(n -> System.out.println(n * n));

This code will print the squares of the numbers, one per line:

Example 3: Using `count`¶

If you have a list of integers and you want to count how many of them are even:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
long countOfEvens = numbers.stream()
                           .filter(n -> n % 2 == 0)
                           .count();

After applying the count operation, countOfEvens will be 2, as there are two even numbers in the list.

Example 4: Using `reduce`¶

Suppose you have a list of numbers and you want to find their product:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
int product = numbers.stream()
                     .reduce((x, y) -> x * y)
                     .orElse(1);

Here, the reduce operation multiplies all the numbers together, and the orElse(1) provides a default value of 1 in case the stream is empty. The result will be 120, which is the product of all the numbers.

These examples should help you understand how to use Intermediate and Terminal Operations in Java 8 Stream API effectively for various data processing tasks.

Method reference¶

Method references in Java 8 provide a concise way to refer to methods or constructors of classes, making your code more readable and maintainable. There are four types of method references:

Reference to a Static Method
Reference to an Instance Method of a Particular Object
Reference to an Instance Method of an Arbitrary Object of a Particular Type
Reference to a Constructor

Let's delve deeper into each type with examples:

Reference to a Static Method:¶

You can reference a static method using the ClassName::staticMethodName syntax. It's similar to lambda expressions and is particularly useful when the lambda expression just calls a single static method.

// Lambda expression
Function<Integer, Double> squareRoot = (x) -> Math.sqrt(x);

// Method reference
Function<Integer, Double> squareRootRef = Math::sqrt;

Reference to an Instance Method of a Particular Object:¶

This type of method reference allows you to invoke an instance method on a specific object. Use the object::instanceMethodName syntax.

String name = "John";
Supplier<Integer> nameLength = name::length;
System.out.println(nameLength.get()); // Outputs: 4

Reference to an Instance Method of an Arbitrary Object of a Particular Type:¶

In this case, you reference an instance method for an object of a particular type. It's useful for scenarios like sorting a list of objects.

List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
names.sort(String::compareToIgnoreCase);

Reference to a Constructor:¶

You can use method references to create instances of classes by referencing constructors using the ClassName::new syntax.

Supplier<List<String>> listSupplier = ArrayList::new;
List<String> myList = listSupplier.get();

Method references help make your code more concise and readable, especially in situations where lambda expressions would otherwise be used. They are a powerful feature introduced in Java 8, enhancing the expressiveness of the language.

Understanding in Detail:¶

Let's break down each type of method reference with more detailed explanations and examples.

1. Reference to a Static Method:¶

Static methods belong to a class rather than an instance. You can reference them using the ClassName::staticMethodName syntax. For example:

Function<Integer, Double> squareRootRef = Math::sqrt;

Here, Math::sqrt refers to the sqrt method of the Math class, which takes an integer as an argument and returns a double. This reference is concise and easy to understand.

2. Reference to an Instance Method of a Particular Object:¶

When you want to invoke an instance method on a specific object, you can use the object::instanceMethodName syntax. For instance:

String name = "John";
Supplier<Integer> nameLength = name::length;

Here, name::length references the length method of the name string, and nameLength.get() will return the length of the string, which is 4.

3. Reference to an Instance Method of an Arbitrary Object of a Particular Type:¶

This type of method reference is often used in situations like sorting lists. You reference an instance method for objects of a particular type. For example:

List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
names.sort(String::compareToIgnoreCase);

Here, String::compareToIgnoreCase refers to the compareToIgnoreCase method of the String class. It allows you to sort the list of names without explicitly specifying a lambda function.

4. Reference to a Constructor:¶

To create instances of classes using method references, you can reference constructors with the ClassName::new syntax. For instance:

Supplier<List<String>> listSupplier = ArrayList::new;
List<String> myList = listSupplier.get();

In this example, ArrayList::new refers to the constructor of the ArrayList class, and listSupplier.get() creates a new ArrayList instance.

Method references simplify your code and make it more readable, as you can express your intent more clearly. They are particularly helpful when working with functional interfaces and lambda expressions in Java 8 and later versions, providing a more concise way to reference methods and constructors.

Practical Examples of Method References:¶

Let's explore practical examples to illustrate the usage of method references in various scenarios:

Example 1: Using Static Method References in Functional Interfaces¶

Suppose you have a list of numbers, and you want to calculate the sum of their squares. You can use a static method reference to Math.pow for this:

List<Double> numbers = Arrays.asList(2.0, 3.0, 4.0);
double sumOfSquares = numbers.stream()
                            .mapToDouble(Math::pow)
                            .sum();
System.out.println("Sum of squares: " + sumOfSquares);

Example 2: Instance Method Reference in Predicate¶

Imagine you have a list of strings, and you want to filter out the ones with a length greater than a certain value. You can use an instance method reference with a Predicate:

List<String> words = Arrays.asList("apple", "banana", "cherry", "date");
int minLength = 5;
List<String> filteredWords = words.stream()
                                  .filter(s -> s.length() >= minLength)
                                  .collect(Collectors.toList());
System.out.println("Filtered words: " + filteredWords);

Here's how you can achieve the same result using an instance method reference:

List<String> filteredWords = words.stream()
                                  .filter(s -> s.length() >= minLength)
                                  .collect(Collectors.toList());

Example 3: Constructor Reference in Stream¶

Suppose you have a list of integers, and you want to create a list of corresponding objects with those integers as values. You can use a constructor reference in a stream:

List<Integer> values = Arrays.asList(1, 2, 3, 4, 5);
List<MyObject> objects = values.stream()
                               .map(MyObject::new)
                               .collect(Collectors.toList());

Here, MyObject::new refers to the constructor of the MyObject class.

These examples demonstrate how method references can simplify your code and make it more readable by replacing lambda expressions with concise references to methods and constructors. By using method references, you can write cleaner and more expressive Java code, making it easier for students, developers, and others to understand and learn from.

Optional Class¶

The Optional class in Java 8 was introduced to tackle the problem of NullPointerExceptions by providing a more expressive and safer way to handle nullable values. It encourages developers to be explicit about the presence or absence of a value, reducing the chances of unexpected null references in their code.

Understanding the Need¶

Before Java 8, dealing with potentially null values in code was often error-prone. Developers would frequently forget to check for null, leading to NullPointerExceptions at runtime. The Optional class aims to address this issue by promoting a clear and structured approach to handling nullable values.

Creating an Optional¶

You can create an Optional instance using various factory methods:

Optional<String> name = Optional.of("John"); // Creates an Optional with a non-null value
Optional<String> emptyName = Optional.empty(); // Creates an empty Optional
Optional<String> nullableName = Optional.ofNullable(getName()); // Creates an Optional from a potentially null value

Avoiding Null Checks¶

One of the primary benefits of Optional is that it encourages you to avoid explicit null checks. Instead, you can use methods like ifPresent, which only executes a block of code if a value is present:

Optional<String> name = Optional.ofNullable(getName());
name.ifPresent(n -> System.out.println("Name is present: " + n));

Handling Absence¶

To perform an action when a value is absent, you can use the orElse method:

Optional<String> name = Optional.empty();
String result = name.orElse("Default Name");

Chaining Operations¶

Optional also supports method chaining, allowing you to perform a series of operations on the value:

Optional<String> name = Optional.of("John");
String upperCaseName = name.map(String::toUpperCase).orElse("No Name");

Filtering Values¶

You can filter values within an Optional using the filter method:

Optional<String> name = Optional.of("Alice");
Optional<String> filteredName = name.filter(n -> n.startsWith("A"));

Dealing with Null Values¶

When working with legacy code that may return null values, you can convert them to Optional to maintain consistency:

String legacyValue = getLegacyValue(); // May return null
Optional<String> optionalValue = Optional.ofNullable(legacyValue);

The Optional class in Java 8 provides a structured and safer approach to handle nullable values, reducing the risk of NullPointerExceptions. By using Optional, developers can write cleaner and more expressive code while making it clear when a value might be absent. This helps improve code quality, readability, and maintainability.

Pitfalls to Avoid¶

While Optional is a powerful tool for handling nullable values, it's essential to use it judiciously and understand its limitations:

Avoid Nesting: Don't nest Optional instances excessively. Use methods like flatMap to handle nested Optional values more elegantly.

   Optional<Optional<String>> nestedName = Optional.of(Optional.of("Nested Name"));
   Optional<String> flattenedName = nestedName.flatMap(Function.identity());

Don't Overuse: Not every variable should be an Optional. Reserve it for cases where the absence of a value has a particular meaning in your domain logic.
Performance: Creating and using Optional instances comes with a minor performance overhead. For most cases, it won't be noticeable, but be mindful in performance-critical scenarios.
Avoid Throwing Exceptions: Avoid calling methods like get() directly on an Optional since it can throw a NoSuchElementException. Use orElse or orElseThrow to provide fallback values or handle exceptional cases.

Optional<String> name = Optional.empty();
String result = name.orElse("Default Name"); // Preferred
String value = name.get(); // Avoid

Null Values in Optional: Although you can put null values into an Optional, it's generally discouraged. The primary purpose of Optional is to eliminate null references, so using it with null values defeats that purpose.

Best Practices¶

To get the most out of Optional, follow these best practices:

Use ifPresent for Side Effects: Use ifPresent when you want to perform an action if a value is present without returning a new value.
Use map and filter for Value Transformation: Use map to transform the value inside an Optional. Use filter to conditionally modify an Optional based on a predicate.
Prefer orElse over orElseGet: orElse is suitable for providing default values, while orElseGet is more efficient when generating the default value involves significant computation.
Embrace Functional Programming: Optional works well with Java's functional programming features like lambdas and streams. Combining them can lead to concise and expressive code.
Think About Domain Semantics: Consider the meaning of absent values in your domain when deciding to use Optional. Make it clear in your code's comments and documentation.

By following these best practices and understanding the purpose and limitations of the Optional class, you can leverage it effectively to prevent NullPointerExceptions and write cleaner, safer, and more maintainable Java code.

Parallel streams¶

Parallel streams in Java 8 offer significant benefits when it comes to processing large data sets concurrently, improving performance, and taking full advantage of multi-core processors. They allow developers to write cleaner, more efficient code for tasks that can be parallelized, making Java applications faster and more scalable.

Java 8 introduced the concept of streams, which provide a functional approach to working with collections of data. Parallel streams take this concept a step further by allowing you to harness the power of multiple cores in modern processors for improved performance. Here are the key benefits of using parallel streams in Java 8:

Improved Performance: Parallel streams enable you to perform operations on a collection of data in parallel, dividing the workload among multiple threads. This can lead to significant performance improvements, especially when dealing with large datasets. For tasks that can be parallelized, you can expect faster execution times compared to sequential processing.
Utilizing Multi-Core Processors: In today's computing environment, most machines come with multi-core processors. Parallel streams allow you to fully utilize these cores, making your Java applications more efficient. Each core can work on a portion of the data simultaneously, maximizing CPU resources.
Cleaner and More Readable Code: Parallel streams promote cleaner and more readable code compared to traditional multithreading approaches. They abstract away the complexity of managing threads manually and allow you to express your intentions more clearly. This leads to code that is easier to maintain and understand.
Conciseness: Parallel stream operations are concise and can often be written in a single line of code. This simplicity reduces the chances of introducing bugs and makes your codebase more concise and elegant.
Automatic Load Balancing: Parallel streams handle the distribution of tasks and load balancing automatically. Java's ForkJoinPool is used under the hood to split the work efficiently among available threads, ensuring that each thread gets a fair share of the work.
Immutable Data: Parallel streams work seamlessly with immutable data structures. This encourages functional programming practices, reducing the risk of data inconsistencies caused by mutable data.
Example - Calculating Sum of Numbers: Here's a simple example to illustrate the benefits of parallel streams. Suppose you have a large list of numbers and want to calculate their sum.

   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

   // Sequential Stream
   int sumSequential = numbers.stream()
       .reduce(0, (a, b) -> a + b);

   // Parallel Stream
   int sumParallel = numbers.parallelStream()
       .reduce(0, (a, b) -> a + b);

In this example, the parallel stream version can take advantage of multiple cores and perform the addition concurrently, potentially resulting in faster execution for large lists.

In conclusion, parallel streams in Java 8 provide a powerful tool for improving the performance of your applications when dealing with data processing tasks that can be parallelized. They simplify concurrent programming, make the code more readable, and take advantage of modern hardware capabilities. However, it's essential to use them judiciously, as not all tasks are suitable for parallelization, and improper usage can lead to performance degradation or even bugs related to thread safety.

Monitoring and Debugging:¶

While parallel streams offer significant advantages, they also come with some considerations, such as monitoring and debugging:

Resource Consumption: Parallel streams consume more system resources due to the creation of multiple threads. Be mindful of this resource usage, especially in a production environment with limited resources.
Thread Safety: Ensure that the operations performed within parallel streams are thread-safe. Data races and concurrency issues can occur if you modify shared data without proper synchronization.
Ordering: In some cases, parallel streams may not preserve the order of elements in the output. If maintaining order is crucial, consider using sequential streams or applying additional sorting operations.
Debugging Complexity: Debugging parallel code can be more challenging than debugging sequential code. When issues arise, identifying the cause of a problem across multiple threads may require specialized debugging tools and techniques.
Choosing the Right Candidates: Not all tasks benefit from parallelization. Some operations, such as simple filtering or mapping on small data sets, may perform better in a sequential stream. It's essential to profile your application and identify the parts that can benefit the most from parallelization.
Example - Parallelism with forEach: Here's an example that demonstrates how to use parallel streams to perform a parallelized operation with forEach.

   List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David", "Eve");

   // Sequential forEach
   names.forEach(name -> System.out.println("Hello, " + name));

   // Parallel forEach
   names.parallelStream()
       .forEach(name -> System.out.println("Hello, " + name));

When using parallel streams with forEach, keep in mind that the order of output may not be the same as the input list due to concurrent processing.

In conclusion, while parallel streams offer substantial benefits for parallelizing data processing tasks in Java 8, it's essential to use them judiciously, considering the nature of the task, thread safety, and debugging challenges. When used appropriately, parallel streams can significantly boost the performance of your Java applications and provide a more responsive user experience.

Mitigating Common Pitfalls:¶

To make the most of parallel streams and avoid common pitfalls, consider the following best practices:

Choose the Right Data Structures: Opt for data structures that are suitable for parallel processing. For example, ArrayList may be more efficient than LinkedList in parallel scenarios due to its better cache locality.
Avoid Stateful Operations: Try to avoid stateful operations, which can lead to unexpected results in parallel streams. Stateful operations are those that rely on the order or state of elements, such as sorted() or distinct(). If needed, apply these operations after parallel processing.
Consider Using Parallelism Safeguards: In some cases, you may want to restrict the degree of parallelism to prevent excessive thread creation. You can achieve this by configuring the underlying ForkJoinPool using System.setProperty("java.util.concurrent.ForkJoinPool.common.parallelism", "n"), where 'n' is the desired parallelism level.
Benchmark and Profile: Always benchmark your code and profile its performance to ensure that parallelization indeed improves the execution time. Profiling tools like VisualVM or Java Flight Recorder can help identify bottlenecks.
Test for Thread Safety: Thoroughly test your code for thread safety. Ensure that shared data is properly synchronized or use thread-safe data structures to prevent data corruption and race conditions.
Use Parallel Streams with Caution for I/O Operations: While parallel streams are excellent for CPU-bound tasks, they may not be suitable for I/O-bound operations, as creating excessive threads for I/O can lead to diminishing returns or even performance degradation. Consider asynchronous programming techniques for I/O-bound tasks.
Graceful Degradation: Implement graceful degradation strategies, such as falling back to sequential processing for small data sets or in cases where parallelization doesn't provide a significant benefit.
Test for Scalability: Assess how well your parallelized code scales with increasing workload. Sometimes, adding more threads may not result in a linear performance improvement due to contention or other factors.

Incorporating these practices into your development workflow will help you maximize the benefits of parallel streams in Java 8 while minimizing potential issues.

In conclusion, parallel streams in Java 8 are a valuable tool for improving the performance of your applications, especially when dealing with large datasets and CPU-bound tasks. However, they should be used judiciously, with careful consideration of thread safety, debugging, and the nature of the task at hand. When applied correctly, parallel streams can significantly enhance the responsiveness and efficiency of your Java applications, benefiting both developers and end-users alike.

Date and Time API (java.time package)¶

Java 8 introduced a new Date and Time API in the java.time package to address the shortcomings of the old java.util.Date and java.util.Calendar classes. This new API provides a more comprehensive and flexible way to work with dates and times, making it easier for developers to handle date and time-related operations.

The Java 8 Date and Time API is based on the ISO calendar system and provides a rich set of classes for representing dates, times, durations, and intervals. It introduces several new classes, including LocalDate, LocalTime, LocalDateTime, ZonedDateTime, Instant, Duration, and Period, among others.

Key Classes and Concepts:¶

1. LocalDate:¶

LocalDate represents a date without a time component. It's suitable for tasks like handling birthdates or any date where time information is not required. Here's an example:

LocalDate today = LocalDate.now();
System.out.println("Current date: " + today);

2. LocalTime:¶

LocalTime represents a time without a date. It's useful for tasks like tracking event timings. Here's an example:

LocalTime currentTime = LocalTime.now();
System.out.println("Current time: " + currentTime);

3. LocalDateTime:¶

LocalDateTime represents a date and time. It's suitable for tasks that require both date and time information. Here's an example:

LocalDateTime dateTime = LocalDateTime.now();
System.out.println("Current date and time: " + dateTime);

4. ZonedDateTime:¶

ZonedDateTime extends LocalDateTime to include time zone information. It's crucial for handling dates and times across different time zones.

ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("America/New_York"));
System.out.println("Current date and time in New York: " + zonedDateTime);

5. Instant:¶

Instant represents a point in time on the timeline in Coordinated Universal Time (UTC). It's suitable for measuring time intervals and working with timestamps.

Instant instant = Instant.now();
System.out.println("Current timestamp in UTC: " + instant);

6. Duration and Period:¶

Duration represents a time-based amount, such as "5 hours" or "30 minutes," while Period represents a date-based amount, such as "3 years" or "2 months." These classes are useful for performing arithmetic operations with time and dates.

Duration duration = Duration.ofHours(5);
System.out.println("5 hours duration: " + duration);

Period period = Period.ofMonths(2);
System.out.println("2 months period: " + period);

Benefits:¶

Improved API design for better readability and maintainability.
Immutable classes ensure thread safety.
Comprehensive support for date and time manipulation.
Time zone support for global applications.
Better handling of leap years and daylight saving time changes.

The Java 8 Date and Time API provides a robust and modern solution for working with dates and times in Java applications. Its easy-to-use classes and methods simplify date and time manipulation tasks, making it a valuable addition to the Java ecosystem for developers, students, and anyone dealing with date and time-related challenges.

Working with Date and Time:¶

Parsing and Formatting Dates and Times:¶

You can parse strings into LocalDate, LocalTime, or LocalDateTime using the DateTimeFormatter class:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");
LocalDate parsedDate = LocalDate.parse("31-01-2024", formatter);
System.out.println("Parsed date: " + parsedDate);

Formatting works the other way around:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");
String formattedDate = LocalDate.now().format(formatter);
System.out.println("Formatted date: " + formattedDate);

Date and Time Arithmetic:¶

Performing arithmetic operations with dates and times is straightforward:

LocalDate today = LocalDate.now();
LocalDate futureDate = today.plusDays(7);
System.out.println("Future date: " + futureDate);

LocalTime now = LocalTime.now();
LocalTime later = now.plusHours(3);
System.out.println("Later time: " + later);

Comparing Dates and Times:¶

You can easily compare dates and times using built-in methods:

LocalDate date1 = LocalDate.of(2024, 1, 31);
LocalDate date2 = LocalDate.of(2023, 12, 31);

if (date1.isAfter(date2)) {
    System.out.println("date1 is after date2");
} else {
    System.out.println("date1 is not after date2");
}

Handling Time Zones:¶

Working with time zones is crucial when dealing with global applications. You can convert between time zones using ZonedDateTime:

ZonedDateTime newYorkTime = ZonedDateTime.now(ZoneId.of("America/New_York"));
ZonedDateTime londonTime = newYorkTime.withZoneSameInstant(ZoneId.of("Europe/London"));
System.out.println("New York time: " + newYorkTime);
System.out.println("London time: " + londonTime);

Daylight Saving Time (DST):¶

The Java 8 Date and Time API automatically adjusts for DST changes, ensuring accurate calculations.

ZonedDateTime beforeDST = ZonedDateTime.of(2023, 3, 12, 1, 30, 0, 0, ZoneId.of("Europe/London"));
ZonedDateTime afterDST = beforeDST.plusHours(1);
System.out.println("Before DST: " + beforeDST);
System.out.println("After DST: " + afterDST);

Handling Time Intervals:¶

The Java 8 Date and Time API also provides convenient methods for dealing with time intervals. You can calculate the difference between two LocalDate, LocalTime, or LocalDateTime objects using Duration:

LocalDateTime start = LocalDateTime.of(2024, 1, 31, 10, 0);
LocalDateTime end = LocalDateTime.of(2024, 1, 31, 14, 30);

Duration duration = Duration.between(start, end);
System.out.println("Duration: " + duration.toHours() + " hours and " + duration.toMinutesPart() + " minutes");

Working with Weekdays and Months:¶

You can easily retrieve information about weekdays and months using the API. For example, checking if a date falls on a weekend:

LocalDate someDate = LocalDate.of(2024, 1, 31);

if (someDate.getDayOfWeek() == DayOfWeek.SATURDAY || someDate.getDayOfWeek() == DayOfWeek.SUNDAY) {
    System.out.println("It's a weekend!");
} else {
    System.out.println("It's a weekday.");
}

You can also get information about the current month:

LocalDate currentDate = LocalDate.now();
Month currentMonth = currentDate.getMonth();
System.out.println("Current month: " + currentMonth);

Converting Legacy Date-Time Types:¶

If you need to work with legacy java.util.Date objects, you can easily convert between the old and new date-time types:

Date legacyDate = new Date();
Instant instant = legacyDate.toInstant();
LocalDateTime localDateTime = instant.atZone(ZoneId.systemDefault()).toLocalDateTime();
System.out.println("Legacy Date converted to LocalDateTime: " + localDateTime);

The Java 8 Date and Time API in the java.time package provides a modern and comprehensive solution for handling dates, times, and intervals in Java applications. It simplifies common tasks, handles time zones and DST changes, and offers excellent readability. Whether you're a developer or a student, mastering this API will greatly enhance your ability to work with date and time data effectively in Java.

Java 8¶

Java 8 Key Features¶

Lambda Expressions:¶

Stream API:¶

Default and Static Methods in Interfaces:¶

Functional Interfaces:¶

Method References:¶

New Date and Time API:¶

Optional Class:¶

Parallel and Concurrent Programming Enhancements:¶

Nashorn JavaScript Engine:¶

Enhanced Collections:¶

Improved Type Inference:¶

Repeatable Annotations:¶

Improved Concurrency with CompletableFuture:¶

Default Methods for Extending Interfaces:¶

Functional Programming Paradigm:¶

Simplified Exception Handling with try-with-resources:¶

Improved Garbage Collection:¶

New and Enhanced APIs:¶

Improved Security with TLS 1.2:¶

Method Parameter Reflection:¶

Enhanced Collections Factory Methods:¶

Compact Profiles:¶

Performance Enhancements:¶

Integration with JavaFX:¶

Easier Migration to Later Versions:¶

Lambda Expressions¶

Capturing Variables in Lambda Expressions¶

Method References and Lambda Expressions¶

Best Practices¶

Stream API¶

Creating a Stream:¶

Stream Operations:¶

Intermediate Operations:¶

Terminal Operations:¶

Example: Filtering and Collecting:¶

Benefits of Streams:¶

Working with Parallel Streams:¶

Stream Example: Mapping and Collecting:¶

Exception Handling:¶

Working with Parallel Streams:¶

Best Practices:¶

Intermediate & Terminal Operations¶

Terminal Operations¶

Example Demonstrations¶

Intermediate Operations Examples:¶

Example 1: Using map and filter¶

Example 2: Using sorted¶

Terminal Operations Examples:¶

Example 1: Using collect¶

Example 2: Using forEach¶

Example 3: Using count¶

Example 4: Using reduce¶

Method reference¶

Reference to a Static Method:¶

Reference to an Instance Method of a Particular Object:¶

Reference to an Instance Method of an Arbitrary Object of a Particular Type:¶

Reference to a Constructor:¶

Understanding in Detail:¶

1. Reference to a Static Method:¶

2. Reference to an Instance Method of a Particular Object:¶

3. Reference to an Instance Method of an Arbitrary Object of a Particular Type:¶

4. Reference to a Constructor:¶

Practical Examples of Method References:¶

Example 1: Using Static Method References in Functional Interfaces¶

Example 2: Instance Method Reference in Predicate¶

Example 3: Constructor Reference in Stream¶

Optional Class¶

Understanding the Need¶

Creating an Optional¶

Avoiding Null Checks¶

Handling Absence¶

Chaining Operations¶

Filtering Values¶

Dealing with Null Values¶

Pitfalls to Avoid¶

Best Practices¶

Parallel streams¶

Monitoring and Debugging:¶

Simplified Exception Handling with `try-with-resources`:¶

Example 1: Using `map` and `filter`¶

Example 2: Using `sorted`¶

Example 1: Using `collect`¶

Example 2: Using `forEach`¶

Example 3: Using `count`¶

Example 4: Using `reduce`¶