title: Android: How can I get access to audio files?
body: <p>In my application I'm using this method to access audio files:</p>
  
  <pre><code>public Cursor pobierzPlikiAudio(){
      String[] STAR = {"*"};
      String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";
      Uri uri= Uri.parse("content://pl/aplikacja/app/provider/MediaStore/Audio");
      return getContentResolver().query(uri, STAR, selection, null, null);
  }
  </code></pre>
  
  <p>but in my LogCat I get a nullPointerException. What is wrong?</p>
  
  <p>Logcat with an error:   </p>
  
  <pre><code>10-29 07:04:17.729: E/AndroidRuntime(24354): FATAL EXCEPTION: main
  10-29 07:04:17.729: E/AndroidRuntime(24354): java.lang.RuntimeException: Unable to start activity ComponentInfo{pl.aplikacja.app/pl.aplikacja.app.MainActivity}: java.lang.NullPointerException
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.ActivityThread.access$600(ActivityThread.java:127)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.os.Handler.dispatchMessage(Handler.java:99)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.os.Looper.loop(Looper.java:137)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.ActivityThread.main(ActivityThread.java:4441)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at java.lang.reflect.Method.invokeNative(Native Method)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at java.lang.reflect.Method.invoke(Method.java:511)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at dalvik.system.NativeStart.main(Native Method)
  10-29 07:04:17.729: E/AndroidRuntime(24354): Caused by: java.lang.NullPointerException
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at pl.aplikacja.app.MainActivity.onCreate(MainActivity.java:18)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.Activity.performCreate(Activity.java:4465)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
  10-29 07:04:17.729: E/AndroidRuntime(24354):    ... 11 more
  </code></pre>
  
  <p>And this is MainActivity.java</p>
  
  <pre><code>package pl.aplikacja.app;
  
  import android.os.Bundle;
  import android.database.Cursor;
  import android.app.Activity;
  import android.view.Menu;
  import android.widget.TextView;
  import android.provider.MediaStore;
  
  public class MainActivity extends Activity {
  
      private Dostawca dostawca;
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
  
         Cursor tablicaPlikow = dostawca.pobierzPlikiAudio();
  
         if (tablicaPlikow.moveToFirst()) {
  
             String title; 
             String artist;  
             String album; 
             int titleColumn = tablicaPlikow.getColumnIndex(MediaStore.EXTRA_MEDIA_TITLE); 
             int artistColumn = tablicaPlikow.getColumnIndex(MediaStore.EXTRA_MEDIA_ARTIST);
             int albumColumn =tablicaPlikow.getColumnIndex(MediaStore.EXTRA_MEDIA_ALBUM); 
  
  
                 // Get the field values
                 title = tablicaPlikow.getString(titleColumn);
                 artist = tablicaPlikow.getString(artistColumn); 
                 album = tablicaPlikow.getString(albumColumn);
  
           TextView widok = (TextView) findViewById(R.id.tekst);
           widok.setText(""+title+" "+ artist + " " + album);
     } 
  
          setContentView(R.layout.activity_main);
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          getMenuInflater().inflate(R.menu.activity_main, menu);
          return true;
      }
  }
  </code></pre>