Android OnClick error
<p>I am currently working through a Java Android book and have hit a problem. I am creating a basic sudoku app and am trying to add a OnClickListener so that when someone hits the 'About' button it displays text, whenever this button is hit I just get the error message as follows. 'The application Sudoku has stopped, please try again.</p>

<p>Here is my code</p>

<p>Manifest file</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.example.sudoku"
    android:versionCode="1"
    android:versionName="1.0" &gt;

    &lt;uses-sdk android:minSdkVersion="8" /&gt;

    &lt;application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"&gt;
        &lt;activity
            android:name=".Sudoku"
            android:label="@string/app_name" &gt;

        &lt;activity 
            android:name=".About"
            android:label="@string/about_title"&gt;
         &lt;/activity&gt;   

            &lt;intent-filter&gt;
                &lt;action android:name="android.intent.action.MAIN" /&gt;

                &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
            &lt;/intent-filter&gt;
      &lt;/activity&gt;

     &lt;/application&gt;

&lt;/manifest&gt;
</code></pre>

<p>I have an about class </p>

<pre><code>package org.example.sudoku;

import android.app.Activity;
import android.os.Bundle;



public class About extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.about);
    }

}
</code></pre>

<p>and lastly is my Sudoku java class</p>

<pre><code>package org.example.sudoku;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.content.Intent;
import android.view.View.OnClickListener;

public class Sudoku extends Activity implements OnClickListener {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        //set up listeners for buttons
        View continueButton = findViewById(R.id.continue_button);
        continueButton.setOnClickListener(this);
        View newButton = findViewById(R.id.new_button);
        newButton.setOnClickListener(this);
        View aboutButton = findViewById(R.id.about_button);
        aboutButton.setOnClickListener(this);
        View exitButton = findViewById(R.id.exit_button);
        exitButton.setOnClickListener(this);



    }

    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.about_button:
            Intent i = new Intent(this, About.class);
            startActivity(i);
            break;
        }

    }
}
</code></pre>

<p>Thanks for looking at this and I'm using eclipse by the way, tryed using the Logcat and De-Bugger but no luck.</p>

<p>LogCat errors</p>

<p>02-13 20:33:08.376: E/AndroidRuntime(524): FATAL EXCEPTION: main
02-13 20:33:08.376: E/AndroidRuntime(524): android.content.ActivityNotFoundException: Unable to find explicit activity class {org.example.sudoku/org.example.sudoku.About}; have you declared this activity in your AndroidManifest.xml?
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1508)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.app.Instrumentation.execStartActivity(Instrumentation.java:1384)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.app.Activity.startActivityForResult(Activity.java:3190)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.app.Activity.startActivity(Activity.java:3297)
02-13 20:33:08.376: E/AndroidRuntime(524):  at org.example.sudoku.Sudoku.onClick(Sudoku.java:34)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.view.View.performClick(View.java:3511)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.view.View$PerformClick.run(View.java:14105)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.os.Handler.handleCallback(Handler.java:605)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.os.Handler.dispatchMessage(Handler.java:92)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.os.Looper.loop(Looper.java:137)
02-13 20:33:08.376: E/AndroidRuntime(524):  at android.app.ActivityThread.main(ActivityThread.java:4424)
02-13 20:33:08.376: E/AndroidRuntime(524):  at java.lang.reflect.Method.invokeNative(Native Method)
02-13 20:33:08.376: E/AndroidRuntime(524):  at java.lang.reflect.Method.invoke(Method.java:511)
02-13 20:33:08.376: E/AndroidRuntime(524):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
02-13 20:33:08.376: E/AndroidRuntime(524):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
02-13 20:33:08.376: E/AndroidRuntime(524):  at dalvik.system.NativeStart.main(Native Method)</p>
