方法 -- 繼承關係

public class test {
    void show() {
        System.out.println("父類別");
    } 
}

public class test2 extends test{
    void show() {
        System.out.println("子類別");
    }
    void Ha() {
        System.out.println("Ha");
    }
}

public class Gogo {
    public static void main(String[] args) {
        test T1 = new test();
        test2 T2 = new test2();
        
        T1.show();
        T2.show();
        
        T1 = T2;
        T1.show();

父子同樣具有show()時，將優先執行子類別
/父類別
/子類別
/子類別

public class test {

    void show(String i) {
        System.out.println("父類別");
   } 
}

public class test2 extends test{
    void show() {
        System.out.println("子類別");
    }
    void Ha() {
        System.out.println("Ha");
    }
}

public class Gogo {
    public static void main(String[] args) {
        test T1 = new test();
        test2 T2 = new test2();
        
        T1.show("ss");
        T2.show();
        
        T1 = T2; 
        T1.show("ss");
    }
}

子不具有show(String)，往父類找，找到發法，執行父類別方法
/父類別
/子類別
/父類別