继承。。。。

    继承
    实例化子类的时候会先调用父类无参的构造方法，
    其他的 变量，和方法
    会遵循：如果子类重写了，就调用重写后的，否则则调用父类的

class Animal{
        //父类成员变量
        String name="Animal's Name";
        String type="Animal's type";
        //父类构造方法
        public Animal(){
            System.out.println("Animal() method execute");
        }
        public Animal(String animalName){
            System.out.println("Animal(String ) method execute");
        }
        //父类方法
        public void canEat(){
            System.out.println("Animal caneat() method execute");
        }
        public void canBreath(){
            System.out.println("Animal canbreath() method execute");
        }
    }
    public class Fish extends Animal{
        //子类的type 成员变量
        String type="Fish's type";
        //以及两个构造方法
        public Fish(){
            System.out.println("Fish() method execute");
        }
        public Fish(String fishName){
            System.out.println("Fish(String s)method execte");
        }
        //重写父类的canBreath 方法
        public void canBreath(){
            System.out.println("Fish can breath");
        }
        public static void main(String args[]){
            Fish f = new Fish();
            System.out.println(f.name);
            System.out.println(f.type);
            System.out.println("------------");
            new Fish().canEat();
            System.out.println("------------");
            new Fish("goldFish").canBreath();
        }
    }
        /*--运行结果
        Animal() method execute
        Fish() method execute
        Animal's Name
        Fish's type
        ------------
        Animal() method execute
        Fish() method execute
        Animal caneat() method execute
        ------------
        Animal() method execute
        Fish(String s)method execte
        Fish can breath
        */