list赋值问题

[城府殿]

for (int i = 0; i < list.length; i++) {
month = new LinkedHashMap();
month.put(list[i], "0");
latest12Months.add(month);
latest12Months2.add(month);
}
System.out.println("latest12Months2---------"+latest12Months2);
List<SecurityAdministrationDto> DH = securityAdministrationService.getDH();
List resultDH = new ArrayList();
for (int i = 0; i < latest12Months.size(); i++) {
for (String key : latest12Months.get(i).keySet()) {
String value = (String) latest12Months.get(i).get(key);
for (int j = 0; j < DH.size(); j++) {
if (key.equals(DH.get(j).getMonth())) {
((Map) latest12Months.get(i)).put(key, DH.get(j).getSum());
}
}
}
}
System.out.println("latest12Months---------"+latest12Months);
System.out.println("latest12Months2---------"+latest12Months2);

Month2没有赋值，为什么会和之前的不一样

[十八道胡同]

((Map) latest12Months.get(i)).put(key, DH.get(j).getSum()); 这句不是修改了吗

[城府殿]

引用 1 楼 LCL_data 的回复:

((Map) latest12Months.get(i)).put(key, DH.get(j).getSum());

这句不是修改了吗

这不是latest12Months2啊

[十八道胡同]

for (int i = 0; i < list.length; i++) { month = new LinkedHashMap(); month.put(list[i], "0"); latest12Months.add(month); latest12Months2.add(month); } 这样的方式创建的month，那你在latest12Months和latest12Months2里面的对应的下标的month是同一个，修改latest12Months里面的自然会把latest12Months2里面的修改掉 如果不想有这种情况，就单独创建一个新的对象存储到latest12Months2 里面。 1楼的回复看不错，不好意思。

[十八道胡同]

package com.demo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        List<HashMap<String,String>> list=new ArrayList<HashMap<String,String>>();
        List<HashMap<String,String>> list2=new ArrayList<HashMap<String,String>>();
        for (int i=0;i<10;i++)
        {
            HashMap<String,String> tmpMap=new HashMap<String,String>();
            tmpMap.put("a","b");
            list.add(tmpMap);
            list2.add(tmpMap);
            System.out.println(System.identityHashCode(list.get(i)) );
            System.out.println(System.identityHashCode(list2.get(i)));
        }
    }
}

[十八道胡同]

System.identityHashCode的问题请参考https://blog.csdn.net/LCL_data/article/details/89205416