Can I use classes that dont extend Activity on android?
<p>I ask this question because I'm getting the stacktrace below. I believe the error is because the classes dont extend activity, because it occurs in lines when I try to instantiate an object of another class.</p>

<pre><code>09-12 15:15:06.370: E/Trace(623): error opening trace file: No such file or directory (2)
09-12 17:06:57.810: E/Trace(675): error opening trace file: No such file or directory (2)
09-12 17:07:06.490: E/AndroidRuntime(675): FATAL EXCEPTION: main
09-12 17:07:06.490: E/AndroidRuntime(675): java.lang.StackOverflowError
09-12 17:07:06.490: E/AndroidRuntime(675):  at java.lang.ref.FinalizerReference.add(FinalizerReference.java:48)
09-12 17:07:06.490: E/AndroidRuntime(675):  at android.os.StrictMode$InstanceTracker.&lt;init&gt;(StrictMode.java:2194)
09-12 17:07:06.490: E/AndroidRuntime(675):  at android.os.StrictMode.trackActivity(StrictMode.java:1896)
09-12 17:07:06.490: E/AndroidRuntime(675):  at android.app.Activity.&lt;init&gt;(Activity.java:746)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.SinglePlayerActivity.&lt;init&gt;(SinglePlayerActivity.java:17)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Board.&lt;init&gt;(Board.java:10)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.GameManager.&lt;init&gt;(GameManager.java:11)
09-12 17:07:06.490: E/AndroidRuntime(675):  at com.zyngawow.tictactoe.Si
</code></pre>
