Java 继承错误:隐式超级构造函数未定义 [英] Java Inheritance error: Implicit Super Constructor is undefined

问题描述

我是 Java 的新手，只是在学习 OOP 概念.请检查我的代码.我收到以下错误.- 隐式超级构造函数未定义.

I am a novice to Java and just learning OOP concepts. Please review my code. I am getting the following error.- Implicit Super Constructor is undefined.

class BoxSuper
{
    int height;
    int length;
    int width;

    BoxSuper(BoxSuper obj)
    {
        height=obj.height;
        length=obj.length;
        width=obj.width;
    }
    BoxSuper(int a,int b,int c)
    {
        height=a;
        length=b;
        width=c;
    }
    BoxSuper(int val)
    {
        height=length=width=val;
    }
    int volume()
    {
        return height*length*width;
    }
}

class BoxSub extends BoxSuper
{
    int weight;
    BoxSub(int a,int b,int c,int d)
    {
        height=a;
        length=b;
        width=c;
        weight=d;
    }
}

推荐答案

您收到此错误是因为 BoxSuper 没有无参数构造函数.在 BoxSub 中调用构造函数期间，如果您没有定义超级构造函数调用，Java 会尝试自动调用无参数 super() 构造函数.

You are receiving this error because BoxSuper does not have a no-arg constructor. During your constructor call in BoxSub, if you do not define the super constructor call Java tries to automatically call the no-arg super() constructor.

或者像这样在 BoxSuper 中定义一个超级构造函数调用:

Either define a super constructor call in BoxSuper like so:

class BoxSub extends BoxSuper
{
    int weight;
    BoxSub(int a,int b,int c,int d)
    {
        super(a, b, c);
        weight=d;
    }
}

或者在 BoxSuper 中定义一个无参数构造函数:

or define a no-arg constructor in BoxSuper:

class BoxSuper
{
    int height;
    int length;
    int width;

    BoxSuper(){}
...

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