title: How to use put and get extra in intents
body: <p>I have two classes, the first one within the onclick i have ;</p>
  
  <pre><code>Intent myIntent = new Intent(getApplicationContext(), PlayGame.class);
          myIntent.putExtra("gameWord", Word.getRandomWord().toUpperCase());
          startActivity(myIntent);
          finish();
  </code></pre>
  
  <p>then within the receiving class's onCreate i have ; </p>
  
  <pre><code>    Bundle extras = getIntent().getExtras();
  
      String secretWord = extras.getString("gameWord");
  </code></pre>
  
  <p>when i try and run the android application i get an error on "startActivity(myIntent);". Any ideas?</p>
  
  <p>here is my logCat;</p>
  
  <pre><code>Shutting down VM
  FATAL EXCEPTION: main
  Process: com.example.hunglikeanandroid, PID: 3431
  java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.hunglikeanandroid/com.example.hunglikeanandroid.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
  at android.app.ActivityThread.access$800(ActivityThread.java:144)
  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
  at android.os.Handler.dispatchMessage(Handler.java:102)
  at android.os.Looper.loop(Looper.java:135)
  at android.app.ActivityThread.main(ActivityThread.java:5221)
  at java.lang.reflect.Method.invoke(Native Method)
  at java.lang.reflect.Method.invoke(Method.java:372)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
  at com.example.hunglikeanandroid.MainActivity.&lt;init&gt;(MainActivity.java:35)
  at java.lang.reflect.Constructor.newInstance(Native Method)
  at java.lang.Class.newInstance(Class.java:1572)
  at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
  </code></pre>