title: Google Glass - Calling a method from another class
body: <p>I am trying to create a scrollable view where the cards are taken from different activities. I have an activity with a card something like this:</p>
  
  <pre><code>public class SampleA extends Activity {
  
      protected void onCreate(Bundle savedInstanceState) 
      { 
          super.onCreate(savedInstanceState);
          getCard();
      }
  
      public Card getCard()
      {
          Card carda = new Card(this);  //ERROR HERE
          carda.setText("card1");
          View cardView = carda.getView();
          setContentView(cardView);
          return carda;
      }
  }
  </code></pre>
  
  <p>And another card which is similar to the above one. Now I am calling the method <code>getCard</code> for both the cards inside another activity which will be my scroll.</p>
  
  <pre><code>public class SampleB extends Activity {
  
      private static ArrayList&lt;Card&gt; sourceCard = new ArrayList&lt;Card&gt;();
      protected void onCreate(Bundle savedInstanceState) 
      { 
          super.onCreate(savedInstanceState);
          sampleaa ss = new sampleaa();
  
          Card card1 = ss.getCard();
          sourceCard.add(card1);
  
          samplec ss1 = new samplec();
          Card card2 = ss1.getCard();
          sourceCard.add(card2);
  
          CardScrollView csvCardsView = new CardScrollView(this);
          csaAdapter cvAdapter = new csaAdapter();
          csvCardsView.setAdapter(cvAdapter);
          csvCardsView.activate();
          setContentView(csvCardsView);
      }
  
      private static class csaAdapter extends CardScrollAdapter {
          //adapter code
      }
  }
  </code></pre>
  
  <p>I am getting a <code>NullPointerException</code> in the above code.</p>
  
  <p>Update
  Pasting the logcat error here:</p>
  
  <pre><code>05-15 17:04:46.646: I/System.out(4832): com.google.android.glass.app.Card@20d7b544
  05-15 17:04:46.771: D/OpenGLRenderer(4832): Enabling debug mode 0
  05-15 17:04:46.826: V/RenderScript(4832): 0x5a36a5b8 Launching thread(s), CPUs 2
  05-15 17:04:46.826: D/RenderScript(4832): Load RS driver 'libRSDriver.so' successfully.
  05-15 17:04:47.873: I/System.out(4832): TAP
  05-15 17:04:47.873: I/System.out(4832): in TAP
  05-15 17:04:47.896: D/AndroidRuntime(4832): Shutting down VM
  05-15 17:04:47.896: W/dalvikvm(4832): threadid=1: thread exiting with uncaught exception (group=0x415e3bd8)
  05-15 17:04:47.896: E/AndroidRuntime(4832): FATAL EXCEPTION: main
  05-15 17:04:47.896: E/AndroidRuntime(4832): Process: com.example.sampleapp, PID: 4832
  05-15 17:04:47.896: E/AndroidRuntime(4832): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sampleapp/com.example.sampleapp.Sampleb}: java.lang.NullPointerException
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2235)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2285)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.ActivityThread.access$800(ActivityThread.java:138)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1236)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.os.Handler.dispatchMessage(Handler.java:102)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.os.Looper.loop(Looper.java:149)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.ActivityThread.main(ActivityThread.java:5061)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at java.lang.reflect.Method.invokeNative(Native Method)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at java.lang.reflect.Method.invoke(Method.java:515)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:610)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at dalvik.system.NativeStart.main(Native Method)
  05-15 17:04:47.896: E/AndroidRuntime(4832): Caused by: java.lang.NullPointerException
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at com.google.android.glass.app.Card.&lt;init&gt;(Card.java:98)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at com.example.sampleapp.Sampleaa.getCard(Sampleaa.java:26)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at com.example.sampleapp.Sampleb.onCreate(Sampleb.java:25)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.Activity.performCreate(Activity.java:5236)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1089)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
  05-15 17:04:47.896: E/AndroidRuntime(4832):     ... 11 more
  05-15 17:04:47.912: I/Process(4832): Sending signal. PID: 4832 SIG: 9
  </code></pre>