Java8 new feature - a reference method

Method references

The method referred to by the name of the method to point to a method.

The method reference can be made more compact and simple construction of the language, to reduce redundant code.

Method references a pair of colon ::.

Examples

• Here, we define four classes method Car cited as an example in Java distinguish four different methods.

package com.nowcoder.main;
 
@FunctionalInterface
public interface Supplier<T> {
    T get();
}
 
class Car {
    //Supplier是jdk1.8的接口，这里和lamda一起使用了
    public static Car create(final Supplier<Car> supplier) {
        return supplier.get();
    }
 
    public static void collide(final Car car) {
        System.out.println("Collided " + car.toString());
    }
 
    public void follow(final Car another) {
        System.out.println("Following the " + another.toString());
    }
 
    public void repair() {
        System.out.println("Repaired " + this.toString());
    }
}

• Constructor reference: The syntax is Class :: new, or more generally Class <T> :: new examples are as follows:

final Car car = Car.create( Car::new );
final List< Car > cars = Arrays.asList( car );

• Static method referenced: its syntax is Class :: static_method, examples are as follows:

cars.forEach( Car::collide );

• The method of any particular class object reference: The syntax is as follows Class :: method Example:

cars.forEach( Car::repair );

• The method of a specific object reference: The syntax is as follows Example instance :: method:

final Car police = Car.create( Car::new );
cars.forEach( police::follow );

Method references instance of

Enter the following code in Java8Tester.java file:

import java.util.List;
import java.util.ArrayList;
 
public class Java8Tester {
   public static void main(String args[]){
      List names = new ArrayList();
 
      names.add("Google");
      names.add("Nowcoder");
      names.add("Taobao");
      names.add("Baidu");
      names.add("Sina");
 
      names.forEach(System.out::println);
   }
}

Example we will System.out :: println method as a static method to reference.

The implementation of the above script, output is:

$ javac Java8Tester.java
$ java Java8Tester
Google
Nowcoder
Taobao
Baidu
Sina

Other new features (Update)

Java8 new features -Lambad expression
Java8 new feature - function interface
Java8 new features - the default method