24-hour format to 12-hour format

I have problem with converting 24-hour format to 12 hour format. This is my code.

    private TimePickerDialog.OnTimeSetListener mTimeSetListener =
        new TimePickerDialog.OnTimeSetListener() {

            @Override
            public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                // TODO Auto-generated method stub
                ViewGroup vg=(ViewGroup) view.getChildAt(0);
                hour = hourOfDay;
                minutes = minute;
                String am_pm = (hourOfDay < 12) ? "AM" : "PM";
                SimpleDateFormat sdf = new SimpleDateFormat("hh:mm a",Locale.US);
                String tme = hour +":"+ minutes+am_pm;
                et1.setText(tme);
            }
        };

I shift to timepicker dialog from alert dialog because i don't know how to change 24-hour to 12-hour format

et1.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new TimePickerDialog(MainActivity.this, mTimeSetListener, hour, minutes, false).show();
            }
        });

    }  

This is the proof that i already turn the boolean impression to false.