java.util.concurrentModification迭代JSONObject时的异常

Question

我有以下代码块,我想将它存储在JSONObject中,以便迭代它并在前端渲染它.

        JSONObject dlCovs = jsonObject.getJSONObject("result").getJSONObject("cov_details");
        Iterator x = dlCovs.keys();
        while (x.hasNext()){
            String key1 = (String) x.next();
            String value1 = dlCovs.optString(key1);
            dlCovs.put("covabbrv",key1);
            dlCovs.put("dcIssuedt",value1);
            dlCovs.put("vecatg",key1);
            dlData.put("dlCovs", dlCovs);
        }

       /* dlCovs.put("covabbrv",cov);
        dlCovs.put("issue_date",issue_date);*/
        dlObj.put("status","valid");
        dlData.put("dlCovs", dlCovs);
        dlData.put("status","valid");

迭代while循环中的数据我得到了java.util.concurrentModificationException,当我尝试调试它时,它也是一个例子,它将值存储在dlData.put("dlCovs",dlCovs)中,但是一旦它第二次迭代它就会抛出错误.我遵循JSON值

 "cov_details": {
     "MCWG": "NA",
     "3WTR": "NA",
     "PSV BUS": "NA",
     "LMV": "NA",
     "INVCRG": "NA"
 },

任何帮助都会非常值得感谢,感谢您提前输入代码

Answer 1

您在迭代其条目时修改地图.你不能这样做.

将项目放入单独的地图中,然后将其添加到"主"地图中:

  Map newEntries = new HashMap();
  Iterator x = dlCovs.keys();
  while (x.hasNext()){
    String key1 = (String) x.next();
    String value1 = dlCovs.optString(key1);
    newEntries.put("covabbrv",key1);
    // .. etc
  }

  dlCovs.putAll(newEntries);

另外:不要使用原始类型.你应该声明x:

Iterator<String> x = dlCovs.keys();

然后你不需要演员:

String key1 = x.next();

同理:

Map<String, String> newEntries = new HashMap<>();