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Lambda expressions are used for anonymous methods, whereas method references are used for existing ones.

Method references have been introduced with Java 8.

There are four types of method references:

• Static method references:

  Syntax:

  	Type::staticMethod
  

  Example:

  	public class App {
  
  		private interface Printable {
  			public void print(String str);
  		}
  
  		public static void main(String[] args) {
  
  			Printable p = App::writeWithStaticRef;
  			p.print("This is an example of static method reference");
  		}
  		
  		public static void writeWithStaticRef(String str) {
  			System.out.println(str);
  		}
  	}
  

• Instance method references:

  Syntax:

  	instance::method
  

  Example:

  	public class App {
  
  		private interface Printable {
  			public void print(String str);
  		}
  
  		public static void main(String[] args) {
  		
  			App app = new App();
  			Printable p2 = app::writeWithInstanceRef; 
  			p2.print("This is an example of instance method reference");		
  		}
  			
  		public void writeWithInstanceRef(String str) {
  			System.out.println(str);
  		}
  	}
  

• References to instance methods of arbitrary objects of a particular type:

  Syntax:

  	Type:method
  

  Example:

  	public class App {
  
  		public static void main(String[] args) {
  		
  			Function function = String::toString;
  			System.out.println(function.apply("Third example"));
  		}
  	}
  

• Constructor references:

  Syntax:

  	Type::new
  

  Example:

  	public class App {
  
  		public static void main(String[] args) {
  		
  			Supplier supplier = App::new;
  			System.out.println(supplier.get().getClass());
  		}
  	}