How to sort file or folder by filename or date at ascending or descending in Android?

Question

The following sample code is from Internet, I hope to sort the List<String> files by filename at ascending or descending. I hope to the List<String> files by date of file at ascending or descending, how can I do ? Thanks!

The same quetsion with List<String> directories.

  List<String> files = Arrays.asList(f.list(new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
            File f=new File(dir, name);               

            return f.isFile()&&(f.isHidden()==false);
        }
    }));
    Collections.sort(files);




List<String> directories = Arrays.asList(f.list(new FilenameFilter() {
    @Override
    public boolean accept(File dir, String name) {
        File f=new File(dir, name);
        return f.isDirectory()&& (f.isHidden()==false);
    }
}));
Collections.sort(directories);

Answer 1

Just provide your File array and it sort simple.

Arrays.sort(files, new Comparator<File>() {
    public int compare(File f1, File f2) {
        return Long.compare(f1.lastModified(), f2.lastModified());
    }
});

Demo:

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


        File path = Environment.getExternalStoragePublicDirectory("/DCIM/Camera");
        File[] filesList = path.listFiles();
        for (int i = 0; i < filesList.length; i++) {
            Date lastModDate = new Date(filesList[i].lastModified());
            Log.i("Pre sorted", "File last modified @ : " + lastModDate.toString());
        }

        Arrays.sort(filesList, new Comparator<File>() {
            public int compare(File f1, File f2) {
                return Long.compare(f1.lastModified(), f2.lastModified());
            }
        });
        Log.i("sorted", "----------------------------------------");
        for (int i = 0; i < filesList.length; i++) {
            Date lastModDate = new Date(filesList[i].lastModified());
            Log.i("Pro sorted", "File last modified @ : " + lastModDate.toString());
        }
    }