Java 8 method reference

Java 8 provides a new feature call method reference. Method reference is used to refer method of functional interface.

There are 3 types of method reference as listed below.

1. Reference to a static method
2. Reference to an instance method
3. Reference to a constructor

I'm going to use same sample to explain the way can use method reference.

1. Reference to a static method

Syntax:

ClassName::staticMethodName

Sample code:

    public class MyPrinter {
     public static void print(String name) {
         System.out.println(name);
     }
    }

   public class PrinterApp {
     public static void main(String[] args) {
         List<String> names = Arrays.asList("Tharanga", "Wijeweera");
         names.forEach(MyPrinter::print);
     }
   }

2. Reference to an instance method

Syntax:

object::instanceMethodName

Sample code:

    public class MyPrinter {
     public void print(String name) {
         System.out.println(name);
     }
   }

   public class PrinterApp {
     public static void main(String[] args) {
         MyPrinter myPrinter = new MyPrinter();
         List<String> names = Arrays.asList("Tharanga", "Wijeweera");
         names.forEach(myPrinter::print);
     }
   }

3. Reference to a constructor

Syntax:

ClassName::new

Sample code:

    public class MyPrinter {

     private String name;

     public MyPrinter(String name) {
         this.name = name;
         print();
     }

     public void print() {
         System.out.println(this.name);
     }
    }

   public class PrinterApp {
     public static void main(String[] args) {
         List<String> names = Arrays.asList("Tharanga", "Wijeweera");
         names.forEach(MyPrinter::new);
     }
   }

Hope this will help you to get an idea about the method reference in Java 8.