在Java中使用for循环创建映射时，Kep的值始终保持为0
在Java中使用for循环创建映射时，Kep的值始终保持为0
提问于 2019-01-30 17:51:34
我正在尝试向Map<String, Map<String, Object>>添加一个Map<String, Object>。
代码如下：
Map<String, Object> createmap = new HashMap<String, Object>();
Map<String, Object> result = new HashMap<String, Object>();
for (int j=0 ; j<jsonarr2.size(); j++ )
{
JSONObject jsonobj2 = (JSONObject) jsonarr2.get(j);
Iterator<String> key2 = jsonobj2.keySet().iterator();
while (key2.hasNext()) {
String k2 = key2.next();
createmap.put(k2, jsonobj2.get(k2));
}
System.out.println("Print J:" + j + " CREATE MAP:" + createmap);
result.put(Integer.toString(j),createmap);
System.out.println("result :" + result);
}For循环运行5次，在createmap中将有5条记录。但是映射result总是使用键0，因此在result映射中只有createmap的最后一条记录可用。
循环内print语句的输出：
Print J:0 CREATE MAP:{vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0001","timestamp":1548643752}}}}
result : {0={vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0001","timestamp":1548643752}}}}}
Print J:1 CREATE MAP:{vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0002","timestamp":1548643752}}}}
result : {0={vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0002","timestamp":1548643752}}}}}
Print J:2 CREATE MAP:{vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0003","timestamp":1548643752}}}}
result : {0={vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0003","timestamp":1548643752}}}}}
Print J:3 CREATE MAP:{vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0004","timestamp":1548643752}}}}
result : {0={vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0004","timestamp":1548643752}}}}}
Print J:4 CREATE MAP:{vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0005","timestamp":1548643752}}}}
result : {0={vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0005","timestamp":1548643752}}}}}但是最终的Map只有
{0={vsan_name={"value":{"0":{"sequence":0,"value":"VSAN0005","timestamp":1548643752}}}}}键始终保持为0，并且值将更新为相同的键。
回答 1
Stack Overflow用户
回答已采纳
发布于 2019-01-30 17:54:12
看起来jsonarr2.size()是1，因此循环只运行一次(即使嵌套的JSONObject有5个键。
此外，您可能会从json数组中跨不同的json对象获取具有相同键的记录。尝试在for循环中移动createMap的实例化，例如：
Map<String, Object> result = new HashMap<String, Object>();
for (int j=0 ; j<jsonarr2.size(); j++ )
{
Map<String, Object> createmap = new HashMap<String, Object>();
JSONObject jsonobj2 = (JSONObject) jsonarr2.get(j);
Iterator<String> key2 = jsonobj2.keySet().iterator();
while (key2.hasNext()) {
String k2 = key2.next();
createmap.put(k2, jsonobj2.get(k2));
}
System.out.println("Print J:" + j + " CREATE MAP:" + createmap);
result.put(Integer.toString(j),createmap);
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/54437657
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