为什么最后一个对象得到一个ArrayList多次复制？ [英] Why does the last object get copied multiple times in an ArrayList?

问题描述

我想的的类的名为城市的对象添加到的ArrayList 。这是code为类

I am trying to add objects of a class named City to an ArrayList. This is the code for the class

public class City {

    public static int x;
    public static int y;

    City(){
        Random rand = new Random();
        this.x = rand.nextInt(100)+1;
        this.y = rand.nextInt(100)+1;
    }
}

这是的code我的主类的

    public static int N = 10;
    public static ArrayList<City> cities = new ArrayList<City>();

    public static void main(String[] args) {        

        for (int i=1; i<N; i++){            
            cities.add(new City());
        }       

        for (City c : cities)
            System.out.print("("+c.x+", "+c.y+")");
    }

}

的println 的结果总是相同的，它似乎像的数组列表的门店只有最后中的所有元素的加入对象。

The result of println is always the same and it seems like the array list stores only the last object added in all of its elements.

例如，当我运行程序我得到的结果是：

For example the results I get when I run the program is:

(52, 93)(52, 93)(52, 93)(52, 93)(52, 93)(52, 93)(52, 93)(52, 93)(52, 93)

为什么我得到的结果？我怎样才能得到它固定？

Why do I get that results? How can I it be fixed?

在此先感谢！

推荐答案

您应该改变你的城市类的成员是非静态的：

You should change the members of your City class to be non static:

public int x;
public int y;

静态成员在类的所有实例中共享，因此所有的实例将具有相同的值。

static members are shared among all instances of a class, so all the instances would have the same values.

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