解析请求返回空JSONArray

Question

I am using parse.com as the server for an android app. I am attempting to query the parse database and get a JSON array, but unfortunately the call for the array is returning null. The following is the code on my app.

ParseUser currentUser = ParseUser.getCurrentUser();
JSONArray myArray = (JSONArray) currentUser.getJSONArray("links");
System.out.println(currentUser.get("username"));
String sample = myArray.toString();
System.out.println(sample);

The following is a sample row from my databse on parse.

objectId String | username String | password String | links Array

AD5HkKpJzB           foug              (hidden)       ["like","this"] 

My code above gets a reference to the current user. I am able to retrieve other data, say "username". Unfortunately, the "links" field returns null. Any help would be appreciated. Thanks.

Note, the above code crashes since myArray is null.

To clarify, ParseUser is a class belonging to parse.com.

The following is my log report.

03-01 21:48:50.687: I/Process(22225): Sending signal. PID: 22225 SIG: 9
03-01 21:49:48.729: I/System.out(22395): foug
03-01 21:49:48.729: D/AndroidRuntime(22395): Shutting down VM
03-01 21:49:48.729: W/dalvikvm(22395): threadid=1: thread exiting with uncaught exception (group=0x414a2930)
03-01 21:49:48.729: E/AndroidRuntime(22395): FATAL EXCEPTION: main
03-01 21:49:48.729: E/AndroidRuntime(22395): java.lang.RuntimeException: Unable to resume activity {com.harris.chain/com.harris.chain.MainActivity}: java.lang.NullPointerException
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2870)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2899)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread.access$600(ActivityThread.java:153)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.os.Looper.loop(Looper.java:137)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread.main(ActivityThread.java:5227)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at java.lang.reflect.Method.invokeNative(Native Method)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at java.lang.reflect.Method.invoke(Method.java:511)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at dalvik.system.NativeStart.main(Native Method)
03-01 21:49:48.729: E/AndroidRuntime(22395): Caused by: java.lang.NullPointerException
03-01 21:49:48.729: E/AndroidRuntime(22395):    at com.harris.chain.MainActivity.getLatestLinks(MainActivity.java:36)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at com.harris.chain.MainActivity.onResume(MainActivity.java:27)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.Activity.performResume(Activity.java:5182)
03-01 21:49:48.729: E/AndroidRuntime(22395):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2860)
03-01 21:49:48.729: E/AndroidRuntime(22395):    ... 12 more

As you can see, I am able to successfully retrieve the username "foug" from the database. But the JSONArray requests still returns null./

Answer 1

For me, hardcoding data directly into Parse's database failed to actually save the data or either didn't allow me to access it from the app. Once I used the app to place data into Parse's database, I was able to retrieve the data.