Gallery with folder filter

You just need to implement MediaScannerConnectionClient in your activity and after that you have to give the exact path of one of the file inside that folder name here as SCAN_PATH and it will scan all the files containing in that folder and open it inside built in gallery. So just give the name of you folder and you will get all the files inside including video. If you want to open only images change FILE_TYPE="image/*"

public class SlideShow extends Activity implements MediaScannerConnectionClient {

        public String[] allFiles;
        private String SCAN_PATH ;
        private static final String FILE_TYPE = "*/*";
        private MediaScannerConnection conn;

        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.main);

            File folder = new File("/sdcard/yourfoldername/");
            allFiles = folder.list();

            SCAN_PATH=Environment.getExternalStorageDirectory().toString()+"/yourfoldername/"+allFiles[0];

            Button scanBtn = (Button) findViewById(R.id.scanBtn);
            scanBtn.setOnClickListener(new OnClickListener()
            {
                public void onClick(View v)
                {
                    startScan();
                }
            });
        }

        private void startScan()
        {
            if(conn!=null)
            {
                conn.disconnect();
            }

            conn = new MediaScannerConnection(this, this);
            conn.connect();
        }


        public void onMediaScannerConnected()
        {
            conn.scanFile(SCAN_PATH, FILE_TYPE);    
        }


        public void onScanCompleted(String path, Uri uri)
        {
            try
            {
                if (uri != null) 
                {
                    Intent intent = new Intent(Intent.ACTION_VIEW);
                    intent.setData(uri);
                    startActivity(intent);
                }
            }
            finally 
            {
                conn.disconnect();
                conn = null;
            }
        }
    }