Java 8 Features: How to Use Lambda Expressions

Check out more about Java 8 LTS in our other blog. We will learn about one of the Java 8 features i.e. Lambda Expressions.

What are Lambda Expressions?

Lambda expressions, also called closures are a new feature in Java 8. It is helpful in writing anonymous methods in a concise and flexible way. Lambda expressions are used to implement the functional interfaces.

How to write Lambda Expression?

Let us analyze it through a code snippet. We will look through lambda expression using the Thread example and Runnable interface which has only one method called – run().

Before Java 8, we used to write the below code –

public class LambdaExample {
	public static void main(String[] args) {
		MyThread mt1 = new MyThread();
		Thread t1 = new Thread(mt1);
		t1.start();

		Thread t2 = new Thread(new Runnable() {
		@Override
		public void run() {
			System.out.println("Running from Thread T2..!!");
                    }
		});
		t2.start();
	}
}

class MyThread implements Runnable {
	@Override
	public void run() {
		System.out.println("Running from MyThread..!!");
	}
}

Output:

Running from MyThread..!!
Running from Thread T2..!!

After Java 8, the same implementation using lambda expression –

public class LambdaExample {
	public static void main(String[] args) {
	Thread t3 = new Thread(() -> { System.out.println("Running from Thread T3..! lambda yay!");
	});
	t3.start();
	}
}

Output:

Running from Thread T3..! lambda yay!

What have we achieved here?

If you observe carefully, we are able to shorten the anonymous method and write it in a more concise way. Please note that lambda expression only works with functional interfaces.

To understand more about this, watch out this video from Telusko –

Further readings

• https://javaconceptoftheday.com/java-8-lambda-expressions/
• A Stackoverflow Discussion
• https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html

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