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POnull pointer exception on calling interface method implemented in other class
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  1. POnull pointer exception on calling interface method implemented in other class
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    copied!<p>I am trying to call the method <code>getFailureDialog()</code> of the interface <code>OnSelectedListener</code>. The method is implemented in <code>MainActivity.java</code>. But when I call the method, I am getting the null pointer exception. </p> <p>I know that its because <code>OnSelectedListener</code> is still not initialized and you are calling <code>getFailureDialog()</code> on uninitialized object. Obviously, interface methods are never initialized. But then how do I call the method <code>getFailureDialog()</code> from my class <code>Common.java</code>?</p> <p>I am placing only the relevant source code below-</p> <p>Source code:</p> <p><strong>SharedFragment.java</strong></p> <pre><code>public class SharedFragment extends DialogFragment { Bundle bundle = getArguments(); final String email = bundle.getString("email"); Thread t=new Thread(new Runnable() { public void run() { common.myRecord(email); } }); t.start(); } </code></pre> <p><strong>Common.java</strong></p> <pre><code>public class Common { OnSelectedListener mCallback; public interface OnSelectedListener { public void getFailureDialog(); } public void myRecord(String email) { mCallback.getFailureDialog(); //null pointer exception here } } </code></pre> <p><strong>MainActivity.java</strong></p> <pre><code>public class MainActivity implements Common.OnSelectedListener { @Override public void getFailureDialog() { RecordFailure fd = new RecordFailure(); fd.show(getSupportFragmentManager(), "dialog"); } } </code></pre> <p><strong>Error Log</strong></p> <pre><code>03-22 15:50:39.032: W/dalvikvm(20796): threadid=16: thread exiting with uncaught exception (group=0x4204c450) 03-22 15:50:39.052: E/AndroidRuntime(20796): FATAL EXCEPTION: Thread-30126 03-22 15:50:39.052: E/AndroidRuntime(20796): java.lang.NullPointerException 03-22 15:50:39.052: E/AndroidRuntime(20796): at com.cornmail.util.Common.myRecord(Common.java:2062) </code></pre>
 

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