Date start -> end

//  WEEK
Calendar first = Calendar.getInstance();
first.add(Calendar.DAY_OF_WEEK, first.getFirstDayOfWeek() - first.get(Calendar.DAY_OF_WEEK));
int startWeek = first.get(Calendar.DATE);
int endWeek = startWeek + 6;

// MONTH
// start = 1
Calendar date = Calendar.getInstance();
date.set(Calendar.DAY_OF_MONTH, first.getActualMaximum(Calendar.DAY_OF_MONTH));
int endMonth = first.get(Calendar.DAY_OF_MONTH);

// format 2 digit
sample: String.format("%02d", first.get(Calendar.DAY_OF_MONTH))