Androidダブルクリックで終了

import android.app.Activity;
import android.app.ActivityManager;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.view.KeyEvent;
import android.widget.Toast;


public class DoubleClickExitHelper {

	private final Activity mActivity;
	
	private boolean isOnKeyBacking;
	private Handler mHandler;
	private Toast mBackToast;
	
	public DoubleClickExitHelper(Activity activity) {
		mActivity = activity;
		mHandler = new Handler(Looper.getMainLooper());
	}
	
	/**
	 * Activity onKeyDown  
	 * */
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		if(keyCode != KeyEvent.KEYCODE_BACK) {
			return false;
		}
		if(isOnKeyBacking) {
			mHandler.removeCallbacks(onBackTimeRunnable);
			if(mBackToast != null){
				mBackToast.cancel();
			}
			//   
			//AppManager.getAppManager().AppExit(mActivity);
			//mActivity.finish();
			AppExit(mActivity);
			return true;
		} else {
			isOnKeyBacking = true;
			if(mBackToast == null) {
				mBackToast = Toast.makeText(mActivity, "        ", 2000);
			}
			mBackToast.show();
			mHandler.postDelayed(onBackTimeRunnable, 2000);
			return true;
		}
	}
	
	private Runnable onBackTimeRunnable = new Runnable() {
		
		@Override
		public void run() {
			isOnKeyBacking = false;
			if(mBackToast != null){
				mBackToast.cancel();
			}
		}
	};

	/**
	 *       
	 */
	public void AppExit(Context context) {
		try {
			ActivityManager activityMgr= (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
			activityMgr.restartPackage(context.getPackageName());
			System.exit(0);
		} catch (Exception e) {	}
	}
}