子類和方法-如何從子類調用方法？

Question

如何從子類調用方法？

Answer 1

希望以下內容能解開你的疑惑：

class SuperA {
    void superMeth1() {
        System.out.println("superMeth1");
    }

    void superMeth2() {
        System.out.println("superMeth2");
    }
}

class Sub1 extends SuperA {
    void superMeth1() {
        System.out.println("superMeth1_sub1");
    }

    void sub1Meth1() {
        System.out.println("subMeth1");
    }
}

public class Main {
    public static void main(String[] args) {
        SuperA obj = new SuperA();
        obj.superMeth1(); // Prints superMeth1
        obj.superMeth2(); // Prints superMeth2

        obj = new Sub1();
        obj.superMeth1(); // Prints superMeth1_sub1
        //obj.sub1Meth1(); // Compilation error as SuperA does not know about Sub1
        ((Sub1) obj).sub1Meth1(); // Prints subMeth1 because of the cast

        Sub1 sub1 = new Sub1();
        sub1.superMeth1(); // Prints superMeth1_sub1
        sub1.sub1Meth1(); // Prints subMeth1
    }
}