CODEWITHSUNDEEP
javaandroidjson
jxdwinter
jxdwinter

Reputation: 2369

Android: json's value is null

In my Android project, when a user logs in, it connects to our server and delivers JSON data to the client. If incorrect username or password is provided, the server responds with JSON data structured as follows:

{
    "d": {
        "__type": "FMService.LoginUser:#StarHope.FMS.Web.Pages.Service",
        "Error": "wrong",
        "Permissions": null,
        "UserInfo": null
    }
}

However, when the user inputs the correct username and password, the value returned from the "Error" key is null. Is this code the correct way to handle this?

try
{
    //when Error is not null
    String error = (String) map.get("Error");   
} 
catch (Exception e)
{
    //when Error is null
}

Upvotes: 1

Views: 163

Answers (2)

ρяσѕρєя K
ρяσѕρєя K

Reputation: 132972

parse your json string as use isNull to check if jsonobject content NULL or not before adding value to Map:

JSONObject jobject=new JSONObject("YOUR_JSON_STRING");


if(!jobject.isNull("d")){
  JSONObject jobjd=jobject.getJSONObject("d");
 String strtype,strError;
  if(jobjd.isNull("__type")){
     strtype=jobjd.getString("__type");
    }
   else{
      //do some code here
        strtype="is null";
    }
  if(jobjd.isNull("Error")){
     strError=jobjd.getString("Error");
    }
   else{
      //do some code here
        strError="is null";
    }
    //.....same code here for Permissions and UserInfo
}

else{
   //do some code here
}

Upvotes: 2

aromero
aromero

Reputation: 25761

You can use getString(). This method will raise a JSONException if the mapping is missing.

public String getString (String name)

Added in API level 1 Returns the value mapped by name if it exists, coercing it if necessary.

Throws JSONException if no such mapping exists.

You can also test if the mapping exists or is null using isNull()

Note that the Error field is inside the d object, not the root.

Upvotes: 1

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