i can't see images on my virtual device

That's work for me

    public static File[] listFiles(Context context) {
        File fileDirectory = context.getFilesDir();
        File[] filteredFiles = fileDirectory.listFiles(new FileFilter() {
            @Override
            public boolean accept(File pathname) {
                if(pathname.getAbsolutePath().contains(".jpg")) {
                   return true;
                } else {
                    return false;
                }
            }
        });

I had this issue but went back to the 'listFiles' method and found some issues in there. Since some of this method was auto-generated by Studio, some of the key variables may be slightly different. I double checked against the code in the video and found inconsistencies in my code. I corrected these and the photos appear now in the emulator.

Thank you very much! Actually I saw some differences between my code and the original one and I tried to change that but now I am getting another error which is basically related with content assist feature of Android Studio. I tried many times with alt+enter to initialize my values but I am getting different options when I hit alt+enter. The video is creating setting page in shared preferences stage.