map遍历删除数据报错 | Java Debug 笔记

for (Object key : map.keySet())
    if (something)
        map.remove(key);

for (Object key : new ArrayList<Object>(map.keySet()))
    if (something)
        map.remove(key);

Map<String, String> map = new HashMap<String, String>() {
  {
    put("test", "test123");
    put("test2", "test456");
  }
};

for(Iterator<Map.Entry<String, String>> it = map.entrySet().iterator(); it.hasNext(); ) {
    Map.Entry<String, String> entry = it.next();
    if(entry.getKey().equals("test")) {
        it.remove();
    }
}

Iterator<Object> it = map.keySet().iterator();

while (it.hasNext())
{
  it.next();
  if (something)
    it.remove();
 }