Task.java

public class Task implements Runnable {
    public static final String TAG = "RUNANABLE";

    private String taskName;
    private Context mContext;

    private ProgressBar progressBar;
    private TextView statusTextView;

        public Task(Context mContext, String taskName, ProgressBar progressBar, TextView statusTextView) {
        this.taskName = taskName;
        this.mContext = mContext;
        this.progressBar = progressBar;
        this.statusTextView = statusTextView;
    }
  /*
    Task to be done in background.
     */
    @Override
    public void run() {
     int step = generateRandomStep();
        try {
            for (int i = 0; i < 100; )
            {
                 i = i + step;
                final int finalI = i;
                
               /*
                To update the progressBar and status TextView, we need to create a new Runnable runs
                on the UI thread as currently this task is running in a background thread.
                */
                
                ((Activity) mContext).runOnUiThread(new Runnable() {
                    @Override
                    public void run() {

                        statusTextView.setText(String.valueOf(finalI) + "%");
                        progressBar.setProgress(finalI);
                    }
                });
                Thread.sleep(500);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    //Generate a Random number that is a factor of 100
    private int generateRandomStep() {
        int multiple[] = new int[]{2,5, 10, 20, 25, 50};
        final int random = new Random().nextInt(5);
        return multiple[random];
    }
}