No USB devices or running detected

    private SensorManager mSensorManager;
    private PowerManager mPowerManager;
    private WindowManager mWindowManager;
    private Display mDisplay;

// onCreate
   @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

       // Get an instance of the SensorManager
        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

        // 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); // main.xml or your xml file name

}

 android:layout_height="wrap_content" android:onClick="@string/clickHandler">

myClickHandler

	public void myClickHandler(View view) {
		switch (view.getId()) {
		// open new class as activity
		case R.id.btnOpenClass: {
				Intent pictureActivity = new Intent(getBaseContext(),
						MyClass.class);
				startActivity(pictureActivity);
		}
		break;			
			
		case R.id.btnAbout: {
			//aboutDialogCreate();
		}
			break;
			
		// open url	
		 case R.id.btnHome: {
		 String url = "//android.okhelp.cz/";
		 Intent i = new Intent(Intent.ACTION_VIEW);
		 i.setData(Uri.parse(url));
		 startActivity(i);
		 }break;

		}

	}// end myClickHandler

// listener .. if click on button will scrolling to mTextView bottom
private OnClickListener mButtonListener = new OnClickListener() {
	    public void onClick(View v) {
	      // do something when the button is clicked
	    int nBottom =	mTextView.getBottom();
	    hScrollView.scrollTo(0, nBottom);
	    }
	};

AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Are you sure you want to exit application?")
       .setCancelable(false)
       .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int id) {
                MyActivity.this.finish(); //Close  this Activity for example: MyActivity.java
           }
       })
       .setNegativeButton("No", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int id) {
                // some code if you want
                dialog.cancel();
           }
       });
AlertDialog alert = builder.create();
alert.show();