Java8

   1 /*
   2 javac LambdaExpressionTest.java 
   3 java -cp . LambdaExpressionTest
   4 */
   5 public class LambdaExpressionTest{
   6     public static void main(String[] args){
   7         System.out.println("LambdaExpressionTest");
   8         // define implementation
   9         // (lambda parameters) -> { // lambda body };
  10         TestIt testIt = (stuffx) -> System.out.println("Stuff " + stuffx);
  11         testIt.sayStuff("Msg");
  12         
  13         // change lambda function implementation
  14         testIt = (stuffxx) -> {
  15             stuffxx = stuffxx.toUpperCase();
  16             System.out.println("OtherStuff " + stuffxx);            
  17         };
  18         testIt.sayStuff("Msg");
  19     }
  20     
  21     // lambda expressions require interfaces to define the expected parameters
  22     public interface TestIt{
  23         void sayStuff(String stuff);
  24     }
  25 }

   1 /*
   2 Usage of :: to refer to a method. Similar in concept to function pointers/callbacks
   3 
   4 javac MethodReferenceExample.java ASD.java 
   5 java -cp . MethodReferenceExample   
   6 
   7 Interface Consumer<T>
   8 Functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
   9 */
  10 
  11 import java.util.ArrayList;
  12 
  13 public class MethodReferenceExample{
  14     public static void main(String[] args){
  15         System.out.println("MethodReferenceExample");
  16         ArrayList<String> al = new ArrayList<String>();
  17         al.add("Str1");
  18         al.add("Str2");
  19         al.add("Str3");
  20         
  21         //For each string in the array list call println having as argument the item
  22         al.forEach(System.out::println);
  23         ASD dummy = new ASD();
  24         al.forEach(dummy::showStuff);
  25     }     
  26 }

   1     public class ASD{
   2         public ASD(){            
   3         }        
   4         
   5         public void showStuff(String message){
   6             System.out.println("Show stuff " + message);
   7         }
   8     }