android - アプリで OnFling メソッドが機能しない

Question

onFling()インテントを使用して前のアクティビティと次のアクティビティの間を移動するはずだった各アクティビティにを実装しました。

しかし、アプリを実行しても機能せず、ログ cat にも表示されません。別の方法でメソッドを呼び出す必要があるか、コードに軽微な間違いがありますか?

 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                float velocityY) {
            // TODO Auto-generated method stub
            Log.d(null,"Fling");
            int dx = (int) (e2.getX() - e1.getX());
            // don't accept the fling if it's too short
            // as it may conflict with a button push
            if (Math.abs(dx) > MAJOR_MOVE && Math.abs(velocityX) > Math.abs(velocityY)) {
                if (velocityX > 0) {
                 //switch to activity on left fling  
                Intent intent = new Intent(this, MainActivity.class);
                startActivity(intent);  

                } else {
                //switch to activity on right fling
                Intent intent = new Intent(this, StudentLife.class);
                startActivity(intent);      


                }
                return true;

            } else {

                return false;
            }
        }

This is the whole class file to clarify some of the questions:

    import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.util.Log;
import android.view.GestureDetector.OnGestureListener;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;

@SuppressWarnings("deprecation")
public class GalleryStudent extends Activity implements OnGestureListener {

     private static final int MAJOR_MOVE = 0;


    public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_galery_student);

            Gallery g = (Gallery) findViewById(R.id.gallery);
            g.setAdapter(new ImageAdapter(this));

            g.setOnItemClickListener(new OnItemClickListener() {
                public void onItemClick(@SuppressWarnings("rawtypes") AdapterView parent, View v, int position, long id) {
                    Toast.makeText(GalleryStudent.this, "" + position, Toast.LENGTH_SHORT).show();
                }
            });
        }


     public boolean onOptionsItemSelected(MenuItem item)
        {

            switch (item.getItemId())
            {   
                case android.R.id.home:
                    // This is called when the Home (Up) button is pressed
                    // in the Action Bar.
                    Intent parentActivityIntent = new Intent(this, 
                    MainActivity.class);
                    parentActivityIntent.addFlags(
                    Intent.FLAG_ACTIVITY_CLEAR_TOP |
                    Intent.FLAG_ACTIVITY_NEW_TASK);
                    startActivity(parentActivityIntent);
                    finish();
                    return true;

                default:

                    return super.onOptionsItemSelected(item);



            }



        }

     public void onBackPressed() {
         Intent startMain = new Intent(Intent.ACTION_MAIN);
            startMain.addCategory(Intent.CATEGORY_HOME);
            startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(startMain);

    }



    public class ImageAdapter extends BaseAdapter {


        int mGalleryItemBackground;
        private Context mContext;

        private Integer[] mImageIds = {
                R.drawable.gmitlogo,
                R.drawable.michaelcarmody,
                R.drawable.fb
        };

        public ImageAdapter(Context c) {
            mContext = c;
            TypedArray a = obtainStyledAttributes(R.styleable.HelloGallery);
            mGalleryItemBackground = a.getResourceId(
                    R.styleable.HelloGallery_android_galleryItemBackground, 0);
            a.recycle();
        }

        public int getCount() {
            return mImageIds.length;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView i = new ImageView(mContext);

            i.setImageResource(mImageIds[position]);
            i.setLayoutParams(new Gallery.LayoutParams(150, 100));
            i.setScaleType(ImageView.ScaleType.FIT_XY);
            i.setBackgroundResource(mGalleryItemBackground);

            return i;
        }
    }

    @Override
    public boolean onDown(MotionEvent e) {
        // TODO Auto-generated method stub
        return false;
    }


    View.OnTouchListener gestureListener = new View.OnTouchListener() {
        public boolean onTouch(View v, MotionEvent event) {
              return detector.onTouchEvent(event);
        }
  };

  setOnTouchListener(gestureListener);




    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
            float velocityY) {
        Log.d(null,"Fling");
        int dx = (int) (e2.getX() - e1.getX());
        // don't accept the fling if it's too short
        // as it may conflict with a button push
        if (Math.abs(dx) > MAJOR_MOVE && Math.abs(velocityX) > Math.abs(velocityY)) {
            if (velocityX > 0) {
             //switch to activity on left fling  
            Intent intent = new Intent(this, StudentLife.class);
            startActivity(intent);  

            } else {
            //switch to activity on right fling
            Intent intent = new Intent(this, StudentPortal.class);
            startActivity(intent);      


            }
            return true;

        } else {

            return false;
        }
    }