1.继承

父类可以调用子类实例对象,(对于调用抽象类必须使用继承)

模版

//抽象定义一个父类抽象类
abstract class FatherAbstract{
    void showFatherAbstract(String color, String name, int age, double serail_abstract){
        System.out.println("color = " + color + ", name = " + name + ", age = " + age + ", enum_example = " + serail_abstract);
    }


}

2.java的类是一个单继承的类,但不意味着不能继承自己父类的父类,继承是可以继承父类的父类的

这边我使用了父类为构造函数

public class FatherClass extends FatherAbstract{
    private final String color;//定义一个不变的变量
    private  String name;
    private  int age;
    public FatherClass(String color,String name, int age) {
//父类的构造类(必须和父类的名字相同)
        this.color = color ;
        this.age =age;
        this.name =name;
    }
    public FatherClass(String color) {
//这边我考虑了特殊情况,final定义的不变的变量,必须定义默认值
        this.color = color ;

    }

    public String getColor() {
        return color;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
//前面是get,set方法获取构造函数的变量
    public void  show(){
//输出打印
        System.out.println("名字: "+this.name +"颜色: "+this.color+ "年龄: "+ age);

    }

}

3.对于接口来说,是定义方法的模版,一个类可以继承多个接口,(可以把它相当与工具)

interface  FatherInterface{
    void showInterface(String color, String name, int age ,double serial );
}

4.枚举要定义一个方法需要定义一个抽象类,并重新其方法

enum  Fatherenum {
    DAY01{
        @Override
        void showEnum(String color, String name, int age, double enum_example) {
            System.out.println("color = " + color + ", name = " + name + ", age = " + age + ", enum_example = " + enum_example);

        }

    };
   abstract void showEnum(String color, String name, int age, double enum_example);



}

5.对比抽象类和接口,其主要区别是 抽象类要写方法体,接口不需要,其次接口是被引用,而抽象类是需要被继承

6.最后复习一下调用

package extendDemo1;

public class ChildrenClass extends FatherClass implements FatherInterface {
//这边因为父类是个构造函数需要传参,子类也需要重构一下
    public ChildrenClass(String color, String name, int age) {
        super(color, name, age);
    }

    public ChildrenClass(String color) {
        super(color);
    }

    public static void main(String[] args) {
//父类调用子类实例类
        FatherClass fatherClass = new ChildrenClass("黄色", "懂帝", 78);
        fatherClass.show();
//引用接口调用被引用接口子类实例类
        FatherInterface fatherInterface = new ChildrenClass("紫色");
        fatherInterface.showInterface("紫色","罗兰",32,02);
//枚举调用其枚举方法(其是隐性的,不能被继承)
        Fatherenum.DAY01.showEnum("土色","黄忠",65,03);
//父类的父类抽象类调用子类实例类(继承也能继承父类的父类)
        FatherAbstract childrenClass = new ChildrenClass("红色");
        childrenClass.showFatherAbstract("红色","吕布",32,87);


    }
//继承了接口必须要重新接口的方法
    @Override
    public void showInterface(String color, String name, int age, double serial) {
        System.out.println("color = " + color + ", name = " + name + ", age = " + age + ", serial = " + serial);

    }
}

运行结果