SimpleLambda.java

package examples;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class SimpleLambda {

 public static void main(String[] args) {
 // ----------------Comparator example-------------- 
 // Traditional way 
 Comparator<String> c1 = new Comparator<String>() {

 @Override
 public int compare(String s1, String s2) {
 return Integer.compare(s1.length(), s2.length());
 }
 
 };
 
 // Lambda way
 Comparator<String> c2 = (String s1, String s2) -> Integer.compare(s1.length(), s2.length());
 //call the comparator by c2.compare("strign1", "string2");
 
 // ----------------Collections sorting example-------------- 
 List<String> names = Arrays.asList("John", "Smith", "Paul");
 // Traditional way
 Collections.sort(names, new Comparator<String>() {

 @Override
 public int compare(String o1, String o2) {
 return o1.compareTo(o2);
 }
 
 });
 
 // Lambda way
 Collections.sort(names, (s1, s2) -> s1.compareTo(s2));
 
 // ----------------Runnable example-------------- 
 // Traditional way 
 Runnable r1 = new Runnable() {
 
 @Override
 public void run() {
 int i = 0; 
 while (i++ < 10) {
 System.out.println("It works");
 }
 }
 };

 // Lambda way
 // If the lambda function has multiple lines use the {}
 // Use the return statement if the lambda function need to return
 // Following modifiers can be put on a lambda expression
 // 1) Final keyword 
 // 2) Annotations
 // It is not possible to specify the return type of a lambda expression
 // We can omit the parameters types in lambda (String s1, String s2) can be written as (s1, s2) 
 Runnable r2 = () -> {
 int i = 0;
 while (i++ < 10) {
 System.out.println("It works");
 }
 };
 //call the runnable by calling r2.run();
 }
}