Question

假设我有A级和B级。那么，在main中，是否可以获得A类的返回值？我现在正在做作业，但似乎无法让它们正确，所以这里我想问的例子......

public class A
{
    private double total=10;
    public double test()
    {
    return total;
    }
}

  public class B extends A
{
    private double totalB=20;
    public double test()
    {
    return (super.test()+10);
    }
}

public class C
{
public static void main(String [] args)
{
    double Sum;
    B FTest = new B();
    System.out.println("I want to get back return value of class A for calculate\n"+FTest.test()/2);
    //So the answer i want to get is suppose to be 5
    System.out.println("Again i want to use return value of class A\n"+FTest.test()*10);
   //Here the value i want to get is 10*10 = 100
}
}

我得到的答案

I want to get back return value of class A for calculate
30.0
Again i want to use return value of class A
300.0

我想要的答案

I want to get back return value of class A for calculate
5
Again i want to use return value of class A
100

所以我问的直接问题是我能在主要的A类中调用test（）方法 B对象。如果可以，怎么样？

Answer 1

由于您已创建了类B的对象，因此您可以获取已在类A中初始化的变量的值，除非您修改了B类test()方法

Answer 2

super关键字可让您访问超类的属性和方法。

由于total中的A是私有的，因此您需要通过A的{{1}}方法获取它。

因此，test应该成为：

Answer 3

这里是我可以写的代码..更多关于你提交的代码中有很多关于类和变量定义的混合器..等等，请参考你的资料

        class A
        {
             int total=10;
            public double test()
            {
            return total;
            }
        }

         class B extends A
        {
            private int total=20;
            public double test()
            {

           return total+10;
            }
        }

        public class C
        {
        public static void main(String [] args)
        {

            A class1 = new A();
            System.out.println("I want to get back return value of class A for calculate");
            //So the answer i want to get is suppose to be 5
            //If override occur only the second time i invoke the method, then how about i want to use it    back again? For calculation.....
            System.out.println("Again i want to use return value of class A"+class1.test()*10);
           //Here the value i want to get is 10*10 = 100
        }
        }

Java函数覆盖

3 个答案: