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POJersey Client on Android - NullPointerException
 

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    <p>I am trying to create a simple Android client for a web service I have built, but something goes wrong at runtime.</p> <p>Here is the Client:</p> <pre><code>public class MyClient extends AsyncTask&lt;EditText, Integer, String&gt; { private EditText text; protected String doInBackground(EditText... strings) { RuntimeDelegate .setInstance(new com.sun.ws.rs.ext.RuntimeDelegateImpl()); WebResource wbr; Client client = Client.create(); wbr = client .resource("http://my.ip:8080/MazeService/rest/service/hello"); String result = wbr.queryParam("number", "10") .accept(MediaType.APPLICATION_JSON).get(String.class); text = strings[0]; return result; } protected void onProgressUpdate(Integer... progress) { // setProgressPercent(progress[0]); } protected void onPostExecute(String result) { if (result != null) this.text.setText(result); else Log.d("MyApp", "No Result"); } </code></pre> <p>}</p> <p>and the Service:</p> <pre><code>@Path("/service") public class AndroidService { @GET @Produces(MediaType.APPLICATION_JSON ) @Path("/hello") public String getJSON(@QueryParam("number") String nr) { String s = "Hi there! The number is: "+nr; return s; } } </code></pre> <p>I get this stacktrace in LogCat:</p> <pre><code>02-18 16:26:06.446: E/AndroidRuntime(1381): FATAL EXCEPTION: AsyncTask #1 02-18 16:26:06.446: E/AndroidRuntime(1381): java.lang.RuntimeException: An error occured while executing doInBackground() 02-18 16:26:06.446: E/AndroidRuntime(1381): at android.os.AsyncTask$3.done(AsyncTask.java:278) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.FutureTask.setException(FutureTask.java:124) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.FutureTask.run(FutureTask.java:137) 02-18 16:26:06.446: E/AndroidRuntime(1381): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.lang.Thread.run(Thread.java:856) 02-18 16:26:06.446: E/AndroidRuntime(1381): Caused by: java.lang.NullPointerException 02-18 16:26:06.446: E/AndroidRuntime(1381): at javax.ws.rs.core.MediaType.valueOf(MediaType.java:119) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.sun.jersey.api.client.ClientResponse.getType(ClientResponse.java:615) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:532) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:506) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.sun.jersey.api.client.WebResource.handle(WebResource.java:674) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.sun.jersey.api.client.WebResource$Builder.get(WebResource.java:503) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.maze.client.MyClient.doInBackground(MyClient.java:25) 02-18 16:26:06.446: E/AndroidRuntime(1381): at com.maze.client.MyClient.doInBackground(MyClient.java:1) 02-18 16:26:06.446: E/AndroidRuntime(1381): at android.os.AsyncTask$2.call(AsyncTask.java:264) 02-18 16:26:06.446: E/AndroidRuntime(1381): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305) 02-18 16:26:06.446: E/AndroidRuntime(1381): ... 5 more </code></pre> <p>I do not understand what the problem is, since a similar client works on PC. There is no problem with the IP address, since I can access the server from the Android VirtualDevice.</p> <p>The Android version is 4.0.3 API version 15. For the client I used Jersey 1.11.</p> <p><strong>EDIT</strong></p> <p>I have also tried to remove the whole thing with the EditText, since someone told me it isn't used as it should be. Still, I got the same error. I simply can not understand what am I doing wrong. If I should display any other additional information, please let me know. Also, ANY idea is good. I am new to Android and I might have made some stupid mistakes.</p>
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    1. COYour problem is a NullPointer something to do with `String result = wbr.queryParam("number", "10") .accept(MediaType.APPLICATION_JSON).get(String.class);`
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    2. CO@Blundell Yes, I thought that might be the problem, but I do not understand WHY does this problem come up, since a simple program containing that code is running perfectly.
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    3. CO@L7ColWinters I do not understand exactly how am I supposed to do that. Please provide some code.
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