Java中的基本构造函数用法 [英] basic constructor usage in java

问题描述

无论出于何种原因，我都无法在其他任何地方找到此问题，也无法在线找到答案。如果我具有以下条件：

For whatever reason, I cannot find this question anywhere else, nor can I find the answer online. If I have the following:

package temp1;

public class MainClass {

    public static void main(String[] args) {
    }

    public MainClass(int radius_x, int area_x, int circumference_x) {
        int radius = radius_x;
        int area = area_x;
        int circumference = circumference_x;
    }

}

假设这甚至是正确的用法，那么我该如何真正使用这里的构造函数中定义的变量？由于作用域，它们只能在构造函数内部工作。

Assuming that this is even correct usage, then how would I actually use the variables defined in the constructor here? They only work inside of the constructor thanks to scope.

推荐答案

您所提供的代码毫无意义，这是正确的。更常见的情况是使用构造函数初始化一些实例变量，然后可以在整个类中使用它们。

You are correct that the code you supply makes little sense. A more common scenario is to use the constructor to initialize a few instance variables, which can then be used throughout the class.

public class MainClass {
    private int radius;
    private int area;
    private int circumference;

    public static void main(String[] args) {
    }

    public MainClass(int radius_x, int area_x, int circumference_x) {
         this.radius = radius_x;
         this.area = area_x;
         this.circumference = circumference_x;
    }

}

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