How show progress bar while read file from SD card

Question

I am reading the list of file from SD card. But my app freezes while it loops through the storage. So I want to show a progress bar before showing all the file.

public ArrayList<MyFile> getPlayList() {
    File home = Environment.getExternalStorageDirectory();
    File[] listFiles = home.listFiles();
    if (listFiles != null && listFiles.length > 0) {
        for (File file : listFiles) {
            if (file.isDirectory()) {
                scanDirectory(file);
            } else {
                addFileToList(file);
            }
        }
    }

    return songsList;
}



@OnClick(R.id.btn_browser)
public void onClickBrowser() {
    // want to show progress bar here when user click a button
    if (fileList == null)
        fileList = fileManager.getPlayList();

    ListDialog listDialog = new ListDialog(this, fileList,
            this, android.R.style.Theme_Black_NoTitleBar_Fullscreen);
    listDialog.show();
}

Answer 1

You need to use asynchronously call getPlayList() . There are various way to use it and I would suggest AsyncTask since fetching files should take < 3s. If it's more then you need to think of some other background solution.

In your AsyncTask,

1. Show the progress indicator during onPreExecute() ,

2. Perform the getPlayList() in doInBackground() ,

3. Finally dismiss the progress indicator and show your ListDialog in onPostExecute() .

That being said, if fetching the playlist is a one time thing and you are fairly certain that the user will anyway click on R.id.btn_browser , then you could prefetch the playlist. That's just a design suggestion.