java8 test

DefultMethodTest.java

interface Father{
    default void eat() {
        System.out.println("I am eating !");
    }
    default void sleep() {
        System.out.println("I am sleeping !");
    }
}
class Son implements Father{
    public void sleep(){
        System.out.println("Son is sleeping !");
    }
}
public class DefultMethodTest {
    public static void main(String[] args){
        Father son = new Son();
        son.eat();
        son.sleep();
    }
}

LambdaTest.java

interface A {
    int cal(int a, int b);
}

public class LambdaTest {
    public static int fun(int m, int n, A a) {
        return a.cal(m, n);
    }

    public static void main(String[] args){
        System.out.println(fun(3, 2, new A(){
            public int cal(int a,int b){
                return a + b;
            }
        }));
        //下面一行和上面一行等价
        System.out.print(fun(3, 2, (a,b) -> a + b));

        System.out.print(fun(3, 2, (a,b) -> a - b));
        System.out.print(fun(3, 2, (a,b) -> a * b));
        System.out.print(fun(3, 2, (a,b) -> a / b));
    }
}

MethodRefTest.java

class Calculator {
    public static int add(int a,int b){
        return a+b;
    }
}
class Student {
    int id;
    String name;
    Student(int id,String name){
        this.id=id;
        this.name=name;
    }
}
interface StudentFactory{
    Student getStudent(int id,String name);
}
public class MethodRefTest {
    public static void main(String[] args){
        //引用普通方法
        A a = Calculator::add;
        System.out.println(a.cal(2,3));
        //引用构造方法
        StudentFactory stuf = Student::new;
        Student stu = stuf.getStudent(1,"yewenlin");
        System.out.println(stu.id+":"+stu.name);
    }
}