JAVA基础-抽象类
1. 用abstract关键字来修饰一个类时, 这个类叫做抽象类, 用abstract修饰一个方法时, 该方法叫做抽象方法
2. 含有抽象方法的类必须被声明为抽象类,
3. 抽象类必须被继承, 抽象方法必须被重写
4. 抽象类不能被实例化
5. 抽象方法只需声明, 不需要实现.
如果派生类派生了个抽象子类不想实现抽象方法, 可以将自己设定为abstract,可以不用重写抽象方法, 让继承他的子类再去重写方法.
abstract class Animal { private String name; Animal(String name) {this.name = name;} public abstract void enjoy(); } class Cat extends Animal { private String eyesColor; Cat(String n,String c) {super(n); eyesColor = c;} public void enjoy() { System.out.println("猫叫声......"); } } class Dog extends Animal { private String furColor; Dog(String n,String c) {super(n); furColor = c;} public void enjoy() { System.out.println("狗叫声......"); } } class Bird extends Animal { Bird() { super("bird"); } public void enjoy() { System.out.println("鸟叫声......"); } } class Lady { private String name; private Animal pet; Lady(String name,Animal pet) { this.name = name; this.pet = pet; } public void myPetEnjoy(){pet.enjoy();} } public class Test { public static void main(String args[]){ Cat c = new Cat("catname","blue"); Dog d = new Dog("dogname","black"); Bird b = new Bird(); Lady l1 = new Lady("l1",c); Lady l2 = new Lady("l2",d); Lady l3 = new Lady("l3",b); l1.myPetEnjoy(); l2.myPetEnjoy(); l3.myPetEnjoy(); } }