Android的JSON和空值 [英] Android Json and null values
问题描述
我怎么能侦测到一个JSON值为null? 例如: [{用户名:空},{用户名:空}]
第一种情况再presents的unexisting用户名并命名为空的第二个用户。但是,如果你尝试检索他们两个值导致在字符串中的空
的JSONObject JSON =新的JSONObject({\你好\:空});
json.put(再见,JSONObject.NULL);
Log.e(日志,json.toString());
Log.e(日志,你好=+ json.getString(你好)+为空?
+(json.getString(你好)== NULL));
Log.e(日志,再见=+ json.getString(再见)+为空?
+(json.getString(再见)== NULL));
日志输出
{你好:空,再见:空}
你好= null是空?假
再见= null是空?假
试着用 json.isNull(字段名)
。
参考:<一href="http://developer.android.com/reference/org/json/JSONObject.html#isNull%28java.lang.String%29">http://developer.android.com/reference/org/json/JSONObject.html#isNull%28java.lang.String%29
How can I detect when a json value is null? for example: [{"username":null},{"username":"null"}]
The first case represents an unexisting username and the second a user named "null". But if you try to retrieve them both values result in the string "null"
JSONObject json = new JSONObject("{\"hello\":null}");
json.put("bye", JSONObject.NULL);
Log.e("LOG", json.toString());
Log.e("LOG", "hello="+json.getString("hello") + " is null? "
+ (json.getString("hello") == null));
Log.e("LOG", "bye="+json.getString("bye") + " is null? "
+ (json.getString("bye") == null));
The log output is
{"hello":"null","bye":null}
hello=null is null? false
bye=null is null? false
Try with json.isNull( "field-name" )
.
Reference: http://developer.android.com/reference/org/json/JSONObject.html#isNull%28java.lang.String%29
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