ClassCastException fragments.MainActivity must implement OnHeadlineSelectedListener

import android.os.Build.VERSION;
//
int nSdkVersion = Integer.parseInt(Build.VERSION.SDK);
int nApiVersion = VERSION.SDK;

    protected void showAbout() {
        // Inflate the about message contents
        View messageView = getLayoutInflater().inflate(R.layout.about, null, false);

        // When linking text, force to always use default color. This works
        // around a pressed color state bug.
        TextView textView = (TextView) messageView.findViewById(R.id.about_credits);
        int defaultColor = textView.getTextColors().getDefaultColor();
        textView.setTextColor(defaultColor);

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setIcon(R.drawable.app_icon);
        builder.setTitle(R.string.app_name);
        builder.setView(messageView);
        builder.create();
        builder.show();
    }

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2009 The Android Open Source Project
          //www.apache.org/licenses/LICENSE-2.0
-->

<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dip">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp"
        android:text="@string/app_descrip"
        android:textColor="?android:attr/textColorPrimaryInverse" />

    <TextView
        android:id="@+id/about_credits"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="20dip"
        android:textSize="16sp"
        android:text="@string/app_credits"
        android:autoLink="web"
        android:textColor="?android:attr/textColorPrimaryInverse" />

</LinearLayout>

TableLayout table = (TableLayout)findViewById(R.id.table);
TableRow row = (TableRow)findViewById(R.id.row);

// get table row index android.
int nIndex = table.indexOfChild(row);
table.removeView(row); // invisible and height == 0
// add row into same place 
table.addView(row, nIndex); // visible

// add row into certain position
table.addView(row, 3); // visible

// create new TableRow dynamically 
TableRow tr = new TableRow(this);
         tr.setLayoutParams(new LayoutParams(
                        LayoutParams.FILL_PARENT,
                        LayoutParams.WRAP_CONTENT));

// create own function for append TableRow
   private void appendRow(TableLayout table) {
        TableRow row = new TableRow(this);

        TextView hLabel = new TextView(this);
        hLabel.setText("Some text");
        hLabel.setPadding(3, 3, 3, 3);

        TextView hNextLabel = new TextView(this);
        hNextLabel.setText("Next text");
        hNextLabel.setPadding(3, 3, 3, 3);
        hNextLabel.setGravity(Gravity.RIGHT | Gravity.TOP);

        row.addView(hLabel, new TableRow.LayoutParams(1));
        row.addView(hNextLabel, new TableRow.LayoutParams());

        table.addView(row, new TableLayout.LayoutParams());
    }

<ScrollView xmlns:android="//schemas.android.com/apk/res/android"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent">
    <TableLayout
                android:id="@+id/table"
                  android:layout_width="fill_parent"
                 android:layout_height="fill_parent">
        <TableRow>
            <TextView android:layout_width="wrap_content"
                      android:layout_height="wrap_content"
                      android:text="Row index 0"/>
        </TableRow>
        <TableRow android:id="@+id/row">
            <TextView android:layout_width="wrap_content"
                      android:layout_height="wrap_content"
                      android:text="Row index 1"/>
        </TableRow>
        <TableRow>
            <TextView android:layout_width="wrap_content"
                      android:layout_height="wrap_content"
                      android:text="Row index 2"/>
        </TableRow>
        <TableRow>
            <TextView android:layout_width="wrap_content"
                      android:layout_height="wrap_content"
                      android:text="Row index 3"/>
        </TableRow>
		</TableLayout>
</ScrollView>

public class _MotionActivity extends Activity implements SensorEventListener {
    private float mSensorX;
    private float mSensorY;
    private Display mDisplay;
    private SensorManager sm;
    private PowerManager mPowerManager;
    private WindowManager mWindowManager;
   
    TextView textview;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Get an instance of the SensorManager
        sm = (SensorManager) getSystemService(SENSOR_SERVICE);
        if(sm.getSensorList(Sensor.TYPE_ACCELEROMETER).size()!=0){
        	Sensor s = sm.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0);
        	sm.registerListener(this,s, SensorManager.SENSOR_DELAY_NORMAL);
        }

        // Get an instance of the PowerManager
        mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);

        // Get an instance of the WindowManager
        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
        mDisplay = mWindowManager.getDefaultDisplay();

 
        
        setContentView(R.layout.main);
        textview = (TextView)findViewById(R.id.textView1);
    }
    
    @Override
    public void onSensorChanged(SensorEvent event) {

    	
        if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER)
            return;

        switch (mDisplay.getRotation()) {
            case Surface.ROTATION_0:
                mSensorX = event.values[0];
                mSensorY = event.values[1];
                textview.setText(String.valueOf( mSensorX));
                break;
            case Surface.ROTATION_90:
                mSensorX = -event.values[1];
                mSensorY = event.values[0];
                textview.setText(String.valueOf( mSensorX));
                break;
            case Surface.ROTATION_180:
                mSensorX = -event.values[0];
                mSensorY = -event.values[1];
                textview.setText(String.valueOf( mSensorX));
                break;
            case Surface.ROTATION_270:
                mSensorX = event.values[1];
                mSensorY = -event.values[0];
                textview.setText(String.valueOf( mSensorX));
                break;
        }

    }

	@Override
	public void onAccuracyChanged(Sensor sensor, int accuracy) {
		// TODO Auto-generated method stub
		
	}
	@Override
	protected void onResume() {
		super.onResume();

             if(sm.getSensorList(Sensor.TYPE_ACCELEROMETER).size()!=0){
        	Sensor s = sm.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0);
        	sm.registerListener(this,s, SensorManager.SENSOR_DELAY_NORMAL);
             }
	}

	@Override
	protected void onPause() {
		
		sm.unregisterListener(this);
		super.onStop();
	}       
    
}