记 Java 各版本新特性

(paramList) -> expression;
或者
(paramList) -> {statments;}

public interface MathOperation {

    int operation(int a, int b);
    
}

public class Tester {

    public static void main(String[] args) {
        MathOperation add = (int a, int b) -> a + b;    //参数列表、表达式返回值相同即可；方法实现甚至可以没有：Lambda表达式相当于一个方法类，作为接口的实现
        System.out.println(add.operation(1, 2));
    }

}

public interface vehicle {
    default void print(){
        System.out.println("我是一辆车!");
    }
}

public interface Vehicle {
    default void print(){
        System.out.println("Vehicle");
    }
}

public interface FourWheeler {
    default void print() {
        System.out.println("FourWheeler");
    }
}

public class Car implements FourWheeler, Vehicle {
    @Override
    public void print() {
        System.out.println("Car");
    }
}

public class Car implements FourWheeler, Vehicle {
    @Override
    public void print() {
        FourWheeler.super.print();    //这里实际上就是普通的调用了接口提供的实现，重载本身没做任何事（当然实际情况下，除了选择接口的实现，往往还会做更多与类自身相关的）
    }
}

public interface Vehicle {
    static void blowHorn() {
        System.out.println("blow horn");　　//就像类的静态方法一样：Vechile.blowHorn();
    }
}