Lambda Expression Introduction

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Definition

A lambda expression can be understood as a concise representation of an anonymous function that can be passed around: it doesn’t have a name, but it has a list of parameters, a body, a return type, and also possibly a list of exceptions that can be thrown. That’s one big definition;

let’s break it down:

• Anonymous— We say anonymous because it doesn’t have an explicit name like a method would normally have: less to write and think about!
• Function— We say function because a lambda isn’t associated with a particular class like a method is.But like a method, a lambda has a list of parameters, a body, a return type, and a possible list of exceptions that can be thrown.
• Passed around— A lambda expression can be passed as argument to a method or stored in a variable.
• Concise— You don’t need to write a lot of boilerplate like you do for anonymous classes.

 

Demo

ThreadTest.java

package org.fool.java8;

public class ThreadTest {
    public static void main(String[] args) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println(Thread.currentThread().getName());
            }
        }).start();

        new Thread(() -> {
            System.out.println(Thread.currentThread().getName());
        }).start();

        new Thread(() -> System.out.println(Thread.currentThread().getName())).start();
    }
}

 

Reference

Manning.Java.8.in.Action.Lambdas.Streams.and.functional-style.programming.Aug.2014