I would like to understand how I can use a cursor to jpg files in a folder specified in the sdcard. I'm trying to select with a cursor the jpg files in a specific folder, and I tried this:

This is the code:

public static Uri getRandomImage(ContentResolver resolver) {

    String[] projection = new String[] {
        BaseColumns._ID,     
    };

    String folder = "/sdcard/DCIM/Wallpaper/";
    folder = folder + "%";
    Uri uri = Media.EXTERNAL_CONTENT_URI;
    String[] whereArgs = new String[]{folder};

    Cursor cursor = resolver.query(uri, projection, null, whereArgs, MediaColumns._ID);

    if (cursor == null || cursor.getCount() <= 0) {
            return null;
    }

    cursor.moveToPosition(new Random().nextInt(cursor.getCount()));

    return Uri.withAppendedPath(uri, cursor.getString(0));
}

but this code gives me error here is the logcat:

E/AndroidRuntime(11986): FATAL EXCEPTION: main
E/AndroidRuntime(11986): android.database.sqlite.SQLiteException: bind or column index out of range: handle 0x26a490
E/AndroidRuntime(11986):    at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:158)
E/AndroidRuntime(11986):    at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:114)
E/AndroidRuntime(11986):    at android.content.ContentProviderProxy.bulkQueryInternal(ContentProviderNative.java:330)
E/AndroidRuntime(11986):    at android.content.ContentProviderProxy.query(ContentProviderNative.java:366)
E/AndroidRuntime(11986):    at android.content.ContentResolver.query(ContentResolver.java:245)
E/AndroidRuntime(11986):    at it.bisemanuDEV.slidepuzzle.SelectImagePreference.getRandomImage(SelectImagePreference.java:126)
E/AndroidRuntime(11986):    at it.bisemanuDEV.slidepuzzle.TileView.newGame(TileView.java:156)
E/AndroidRuntime(11986):    at it.bisemanuDEV.slidepuzzle.SlidePuzzleActivity.onOptionsItemSelected(SlidePuzzleActivity.java:377)
E/AndroidRuntime(11986):    at android.app.Activity.onMenuItemSelected(Activity.java:2762)
E/AndroidRuntime(11986):    at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:730)
E/AndroidRuntime(11986):    at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143)
E/AndroidRuntime(11986):    at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855)
E/AndroidRuntime(11986):    at com.android.internal.view.menu.IconMenuView.invokeItem(IconMenuView.java:532)
E/AndroidRuntime(11986):    at com.android.internal.view.menu.IconMenuItemView.performClick(IconMenuItemView.java:122)
E/AndroidRuntime(11986):    at android.view.View$PerformClick.run(View.java:8819)
E/AndroidRuntime(11986):    at android.os.Handler.handleCallback(Handler.java:603)
E/AndroidRuntime(11986):    at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime(11986):    at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(11986):    at android.app.ActivityThread.main(ActivityThread.java:4627)
E/AndroidRuntime(11986):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(11986):    at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime(11986):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
E/AndroidRuntime(11986):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
E/AndroidRuntime(11986):    at dalvik.system.NativeStart.main(Native Method)