图像滑动无法正常工作

Question

我有一个GridView，我在其中显示图像。单击图像，图像将扩展为全屏。一切都很好。现在我想刷这些图像。当我滑动图像时，没有任何反应。它仍然保持原样。任何人都可以帮助我，代码中有什么不对。下面是我的代码和布局文件。

public class MainActivity extends Activity {

    private GridView gridview;
    private int j = 0;

    private final GestureDetector detector = new GestureDetector(new SwipeGestureDetector());
    private static final int SWIPE_MIN_DISTANCE = 120;
    private static final int SWIPE_THRESHOLD_VELOCITY = 200;

    // Create Array thumbs resource id's:
    private int thumb[] = { R.drawable.logowhite,
            R.drawable.logo_bg,
            R.drawable.logowhite,
            R.drawable.logo_bg,
            R.drawable.logowhite,
            R.drawable.logo_bg, };

    private ImageView expandedImageView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the variables:
        gridview = (GridView) findViewById(R.id.gridView);

        // Set an Adapter to the ListView
        gridview.setAdapter(new ImageAdapter(this));

        // Set on item click listener to the ListView
        gridview.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View v, int pos,
                                    long id) {
                j = pos;
                setContentView(R.layout.slide_image);
                expandedImageView = (ImageView) findViewById(R.id.imageViewslides);
                expandedImageView.setBackgroundResource(thumb[pos]);

            }
        });
    }

    // Create an Adapter Class extending the BaseAdapter
    class ImageAdapter extends BaseAdapter {
        private LayoutInflater layoutInflater;
        public ImageAdapter(MainActivity activity) {
            // TODO Auto-generated constructor stub
            layoutInflater = (LayoutInflater) activity
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }
        @Override
        public int getCount() {
            // Set the count value to the total number of items in the Array
            return thumb.length;
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // Inflate the item layout and set the views
            View listItem = convertView;
            int pos = position;
            if (listItem == null) {
                listItem = layoutInflater.inflate(R.layout.grid_item, null);
            }

            // Initialize the views in the layout
            ImageView imgView = (ImageView) listItem.findViewById(R.id.thumb);
            // Set the views in the layout
            imgView.setBackgroundResource(thumb[pos]);
            return listItem;
        }

    }

    private class SwipeGestureDetector extends GestureDetector.SimpleOnGestureListener {
        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
            try {
                if (e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
                    if(thumb.length>j) {
                        j++;
                        if(j < thumb.length){
                            expandedImageView.setImageResource(thumb[j]);
                            return true;
                        }
                        else {
                            j = 0;
                            expandedImageView.setImageResource(thumb[j]);
                            return true;
                        }
                    }
                }
                else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
                    if(j>0){
                        j--;
                        expandedImageView.setImageResource(thumb[j]);
                        return true;
                    }
                    else {
                        j = thumb.length-1;
                        expandedImageView.setImageResource(thumb[j]);
                        return true;
                    }
                }
            }
            catch (Exception e) {
                e.printStackTrace();
            }
            return false;
        }
      }
}

布局文件是：activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context="com.mukesh.gridviewimageswipe.MainActivity">

    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/container"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >

        <GridView
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:columnWidth="80dp"
        android:horizontalSpacing="10dp"
        android:numColumns="2"
        android:stretchMode="columnWidth"
        android:verticalSpacing="10dp" >
    </GridView>

        <ImageView
        android:id="@+id/expanded_image"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:contentDescription="@string/app_name"
        android:visibility="invisible" />
    </FrameLayout>
</RelativeLayout>

grid_item.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="5dp" >

    <ImageView
    android:id="@+id/thumb"
    android:layout_width="72dp"
    android:layout_height="72dp"
    android:layout_centerHorizontal="true"
    android:contentDescription="@string/app_name" />
</RelativeLayout>

slide_image.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
    android:id="@+id/imageViewslide"
    android:layout_width="fill_parent"
    android:layout_height="420dp"
    android:orientation="horizontal"
    android:layout_below="@+id/textq">
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/imageViewslides">
    </ImageView>
</LinearLayout>
</LinearLayout>