Using java lambda to create threads using runnable interface in java

I am using jdk-11 for this tutorial.

We are going to use lambda functions to create a thread in java. In this tutorial, we will implement Runnable  interface.

Our lambda implementation will print numbers from the range 1 to 10.

Step 1 :- implement Runnable interface

Runnable runThroughLambda = () -> IntStream.rangeClosed(1, 10)
                                           .forEach(System.out::println);

In above code, I created a stream of integers from 1 to 10. And then, the integers are Printed it to console.

Step 2 :- Pass the implementation of runnable created above to create a thread object.

Thread threadUsesLambda = new Thread(runThroughLambda);

We created a thread object, and we passed the lambda in it’s constructor.

We could have done this too.

Thread threadUsesLambda = new Thread(() -> IntStream.rangeClosed(1, 10)
                                                     .forEach(System.out::println));

We can also pass lambda directly in the constructor, but defining separate variable makes it more readable.

Step 3 :- Now, we are going to start the thread.

threadUsesLambda.start();

OutPut :-  

1
2
3
4
5
6
7
8
9
10

OR

We can put entire code in one line, and save space. 🙂

new Thread(() -> IntStream.rangeClosed(1, 10).forEach(System.out::println)).start();

OR

We can format the code to make it more readable.

new Thread(() -> IntStream.rangeClosed(1, 10)
                          .forEach(System.out::println))
    .start();

But, it is always good to use variables to isolate small parts to make it more readable and maintainable.

Complete Code :-

package com.threading;

import java.util.stream.IntStream;

public class LambdaRunnable {
    public static void main(String[] args) {
        Runnable runThroughLambda = () -> IntStream.rangeClosed(1, 10)
                                                    .forEach(System.out::println);

        Thread threadUsesLambda = new Thread(runThroughLambda);

        threadUsesLambda.start();
    }
}