title: How to Clear content on the layout?
body: <p>I just create a app for writing the text on Screen using TouchEvent method. It works fine. See this is code</p>
  
  <pre><code>public TouchEventView(Context context, AttributeSet attrs) {
      super(context, attrs);
  
      paint.setAntiAlias(true);
      paint.setColor(Color.WHITE);
      paint.setStyle(Paint.Style.STROKE);
      paint.setStrokeJoin(Paint.Join.ROUND);
      paint.setStrokeWidth(5f);
  }
  
  @Override
  protected void onDraw(Canvas canvas) {
      canvas.drawPath(path, paint);
  }
  
  @Override
  public boolean onTouchEvent(MotionEvent event) {
      float x = event.getX();
      float y = event.getY();
      switch (event.getAction()) {
      case MotionEvent.ACTION_DOWN:
          path.moveTo(x, y);
          return true;
      case MotionEvent.ACTION_MOVE:
          path.lineTo(x, y);
          break;
      default:
          return false;
      }
      invalidate();
      return true;
  </code></pre>
  
  <p><strong>After, that i've written code for clear the content in layout : -</strong> </p>
  
  <pre><code>LinearLayout li = (LinearLayout)findViewById(R.id.linear);
      li.clearAnimation();
  </code></pre>
  
  <p><strong>My Logcat</strong></p>
  
  <pre><code>11-18 16:10:18.681: I/System.out(22859): This is a log message
  11-18 16:10:18.681: E/Mein Tag(22859): Hello
  11-18 16:10:20.581: W/KeyCharacterMap(22859): No keyboard for id 0
  11-18 16:10:20.581: W/KeyCharacterMap(22859): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
  11-18 16:10:21.721: D/AndroidRuntime(22859): Shutting down VM
  11-18 16:10:21.721: W/dalvikvm(22859): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
  11-18 16:10:21.731: E/AndroidRuntime(22859): FATAL EXCEPTION: main
  11-18 16:10:21.731: E/AndroidRuntime(22859): java.lang.NullPointerException
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at de.vogella.android.touch.WriteOnScreenActivity.clear(WriteOnScreenActivity.java:47)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at de.vogella.android.touch.WriteOnScreenActivity.onOptionsItemSelected(WriteOnScreenActivity.java:38)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at android.app.Activity.onMenuItemSelected(Activity.java:2195)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:730)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.view.menu.IconMenuView.invokeItem(IconMenuView.java:532)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.view.menu.IconMenuItemView.performClick(IconMenuItemView.java:122)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at android.view.View$PerformClick.run(View.java:8816)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at android.os.Handler.handleCallback(Handler.java:587)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at android.os.Handler.dispatchMessage(Handler.java:92)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at android.os.Looper.loop(Looper.java:123)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at android.app.ActivityThread.main(ActivityThread.java:4627)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at java.lang.reflect.Method.invokeNative(Native Method)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at java.lang.reflect.Method.invoke(Method.java:521)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
  11-18 16:10:21.731: E/AndroidRuntime(22859):    at dalvik.system.NativeStart.main(Native Method)
  11-18 16:22:15.801: I/System.out(23179): This is a log message
  11-18 16:22:15.811: E/Mein Tag(23179): Hello
  </code></pre>
  
  <p>When i press the clear button, i got Nullpointer Exception for this app. What am doing wrong?</p>
  
  <p>Anyone Guide me.</p>