Question

下午好。

我有一个City类，它接收到其他City对象的距离值不同。

但是，在创建城市并添加距离之后，每个城市都会获得相同的距离值，这是上一次添加的城市的值。

也就是说，运行后，cityA.toString的输出应为{B = 5，C = 4，D = 7，E = 6，F = 5，G = 7，H = 4，I = 2， J = 9}，而不是{A = 6，B = 5，C = 5，D = 6，E = 4，F = 8，G = 5，H = 4，I = 3，J = 8}

您知道我在做什么错吗？谢谢

public class City {

private String name;
private static HashMap<String, Integer> distancias;

public City(String name){
    this.name = name;
    distancias = new HashMap<String, Integer>();
}

public void insertDistances(City city, int dist) {
    distancias.put(city.getName(), dist);
}


public static void main(String[] args) {

    City cityA = new City("A");
    City cityB = new City("B");
    City cityC = new City("C");
    City cityD = new City("D");
    City cityE = new City("E");
    City cityF = new City("F");
    City cityG = new City("G");
    City cityH = new City("H");
    City cityI = new City("I");
    City cityJ = new City("J");

    cityA.insertDistances(cityB, 5);
    cityA.insertDistances(cityC, 4);
    cityA.insertDistances(cityD, 7);
    cityA.insertDistances(cityE, 6);
    cityA.insertDistances(cityF, 5);
    cityA.insertDistances(cityG, 7);
    cityA.insertDistances(cityH, 4);
    cityA.insertDistances(cityI, 2);
    cityA.insertDistances(cityJ, 9);

    cityB.insertDistances(cityA, 6);
    cityB.insertDistances(cityC, 5);
    cityB.insertDistances(cityD, 6);
    cityB.insertDistances(cityE, 4);
    cityB.insertDistances(cityF, 8);
    cityB.insertDistances(cityG, 5);
    cityB.insertDistances(cityH, 4);
    cityB.insertDistances(cityI, 3);
    cityB.insertDistances(cityJ, 8);

}

}

Answer 1

private static HashMap<String, Integer> distancias;

删除静态改为使用private HashMap<String, Integer> distancias`

静态变量是类的所有实例（或对象）所共有的，因为它是类级别的变量。

Java对象未保存其属性值

1 个答案: