java 多态

package com.study;

class Base {
   int count = 20;
   public void show(){
       System.out.println(this.count);
   }
}
class Sub extends Base {
    int count = 10;
    public void show(){
        System.out.println(this.count);
    }
}
public class Test {
    public static void main(String[] args) {
        Sub sub = new Sub();
        System.out.println(sub.count);
        sub.show();// 10 
        Base base = sub; // 多态
        System.out.println(base==sub);
        System.out.println(base.count);// 20 多态，属性，看左边
        base.show();// 10 多态, 方法：编译看左边，运行看右边
    }
}

package com.study;
public class Test {
    public static void main(String[] args) {
        Base base = new Sub();
        base.test(1,2,3); // bbb 多态，编译看左边运行看右边
        Sub sub = (Sub)base;
        sub.test(1,2,3); // ccc
    }
}
class Base{
    public void test(int a,int ... arr ){
        System.out.println("aaa");
    }
}
class Sub extends Base{
    public void test(int a,int[] arr ){
        System.out.println("bbb");
    }
    public void test(int a,int b,int c ){
        System.out.println("ccc");
    }
}