title: Can't get a button to bring up a new activity
body: <p>I'm quite new to programming and have just hit a simple road block that is holding me up.  I am trying to have a button from my main activity call up another activity.  I've researched but as yet I haven't found something to work (probably really simple and stupid).  Any help would be appreciated.  I've included the code for my main activity.  Thank you</p>
  
  <pre><code>package com.example.valentinetimer;
  
  
  import android.app.Activity;
  import android.content.Intent;
  import android.os.Bundle;
  import android.util.Log;
  import android.view.View;
  import android.view.View.OnClickListener;
  import android.widget.Button;
  
  
  public class CardFront extends Activity implements OnClickListener {
  
      private static final String TAG = null;
  
      Button openButton;
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.cardfrontxml);
  
      Log.d(TAG, "onCreate");
  
      //Button
      openButton = (Button) findViewById(R.id.openButton);
      openButton.setOnClickListener(this);
  
      this.setContentView(R.layout.cardfrontxml);
      this.openButton = (Button)this.findViewById(R.id.openButton);
      this.openButton.setOnClickListener(new OnClickListener()
      {
          @Override
          public void onClick(View v)
          {
              Log.d(TAG, "Click Event");
  
              Intent intent = new Intent (null, CardContent.class);
              startActivity (intent);
          }
      });
      //End Button
  
  }
  
      @Override
      public void onClick(View v)
      {
          // TODO Auto-generated method stub  
      }
  }
  </code></pre>
  
  <p>LogCat:</p>
  
  <pre><code>02-08 10:18:51.927: E/AndroidRuntime(2494): FATAL EXCEPTION: main
  02-08 10:18:51.927: E/AndroidRuntime(2494): android.content.ActivityNotFoundException:          Unable to find explicit activity class   {com.example.valentinetimer/com.example.valentinetimer.CardContent}; have you declared this   activity in your AndroidManifest.xml?
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1504)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.app.Instrumentation.execStartActivity(Instrumentation.java:1382)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.app.Activity.startActivityForResult(Activity.java:3095)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.app.Activity.startActivity(Activity.java:3201)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at com.example.valentinetimer.CardFront$1.onClick(CardFront.java:42)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.view.View.performClick(View.java:3110)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.view.View$PerformClick.run(View.java:11928)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.os.Handler.handleCallback(Handler.java:587)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.os.Handler.dispatchMessage(Handler.java:92)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.os.Looper.loop(Looper.java:132)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at android.app.ActivityThread.main(ActivityThread.java:4025)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at java.lang.reflect.Method.invokeNative(Native Method)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at java.lang.reflect.Method.invoke(Method.java:491)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
  02-08 10:18:51.927: E/AndroidRuntime(2494):     at dalvik.system.NativeStart.main(Native Method)
  </code></pre>