Sudoku crashes when 'about' button is clicked
<p>Hi I am new to android and I have been trying to do a simple sudoku application.
I am facing a problem now,whenever i click the "about" button the applocation  tends to stop and takes me back to my menu screen.
Can anyone suggest what is the problem for crash??</p>

<p>Below here is my code:</p>

<p>Sudoku.java</p>

<pre><code>public class Sudoku extends Activity implements OnClickListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sudoku);
    View continueButton=findViewById(R.id.button1);
    continueButton.setOnClickListener(this);
    View newButton=findViewById(R.id.button2);
    newButton.setOnClickListener(this);
    View aboutButton=findViewById(R.id.button3);
    aboutButton.setOnClickListener(this);
    View exitButton=findViewById(R.id.button4);
    exitButton.setOnClickListener(this);
}

        public void onClick(View v){
        switch(v.getId()){
        case R.id.button3:
            Intent i = new Intent(this, About.class);
            startActivity(i);
            break;
        case R.id.button4:
            finish();
            break;

            }
          }
        @Override
           public boolean onCreateOptionsMenu(Menu menu) {
              super.onCreateOptionsMenu(menu);
              MenuInflater inflater = getMenuInflater();
              inflater.inflate(R.menu.menu, menu);
              return true;
           }

 }
</code></pre>

<p>About.java</p>

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

<p>about.xml:</p>

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

<p>string.xml:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
</code></pre>

<p></p>

<pre><code>&lt;string name="app_name"&gt;Sudoku&lt;/string&gt;
&lt;string name="action_settings"&gt;Settings&lt;/string&gt;
&lt;string name="hello_world"&gt;Application Sudoku&lt;/string&gt;
&lt;string name="continue_label"&gt;Continue&lt;/string&gt;
&lt;string name="new_game_label"&gt;New Game&lt;/string&gt;
&lt;string name="about_label"&gt;About&lt;/string&gt;
&lt;string name="exit_label"&gt;Exit&lt;/string&gt;
&lt;string name="about_title"&gt;About Android Sudoku&lt;/string&gt;
&lt;string name="about_text"&gt;\Sudoku is a logic-based number placement puzzle.
</code></pre>

<p>Starting with a partially completed 9x9 grid, the
objective is to fill the grid so that each
row, each column, and each of the 3x3 boxes
(also called <i>blocks</i>) contains the digits
1 to 9 exactly once..</p>

<p></p>

<p>activity_sudoku.xml</p>

<pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="@color/background"
tools:context=".Sudoku" &gt;

&lt;TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/hello_world"
    android:textStyle="italic" /&gt;

&lt;TableLayout 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:stretchColumns="*"&gt;
    &lt;TableRow &gt;

&lt;Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_below="@+id/textView1"
    android:layout_marginTop="22dp"
    android:text="@string/continue_label"
    android:textStyle="italic"
     /&gt;

&lt;Button
    android:id="@+id/button2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/button1"
    android:layout_below="@+id/button1"
    android:layout_marginTop="21dp"
    android:text="@string/new_game_label" 
    android:textStyle="italic"
    /&gt;


&lt;/TableRow&gt;
&lt;TableRow &gt;

    &lt;Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="@string/about_label"
         /&gt;

    &lt;Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="@string/exit_label"
         /&gt;

&lt;/TableRow&gt;
&lt;/TableLayout&gt;

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

<p>Sudoku Manifest.xml:</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"
    android:targetSdkVersion="17" /&gt;

&lt;application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" &gt;
    &lt;activity
        android:name="org.example.sudoku.Sudoku"
        android:label="@string/app_name" &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;activity
        android:name="org.example.sudoku.About"
        android:label="@string/about_title"
        android:theme="@android:style/Theme.Dialog"&gt;
    &lt;/activity&gt;
&lt;/application&gt;

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