What is Lambda Expression in Java?

A Lambda Expression is a feature introduced in Java 8 that allows you to write short and clean implementations of functional interfaces without creating a separate class. It helps reduce boilerplate code and makes Java programming more concise and readable.

In simple terms, a lambda expression represents an anonymous function — a method without a name.

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🔹 Why Lambda Expressions?

Before Java 8, implementing interfaces like Runnable required extra code.

Before Lambda:

Runnable r = new Runnable() {
    public void run() {
        System.out.println("Running thread");
    }
};

Using Lambda Expression:

Runnable r = () -> System.out.println("Running thread");

✅ Less code
✅ Better readability
✅ Functional programming support

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🔹 Syntax of Lambda Expression

(parameters) -> { body }

Example:

(a, b) -> a + b

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🔹 Functional Interface

Lambda expressions work only with Functional Interfaces, which contain exactly one abstract method.

Example:

@FunctionalInterface
interface Add {
    int sum(int a, int b);
}

public class Test {
    public static void main(String[] args) {
        Add obj = (a, b) -> a + b;
        System.out.println(obj.sum(5, 3));
    }
}

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🔹 Common Use Cases

✅ Multithreading (Runnable)
✅ Collections sorting
✅ Stream API operations
✅ Event handling

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✅ Advantages

• Reduces code length

• Improves readability

• Enables functional programming style

• Works perfectly with Stream API

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