问如何计算两个日期间的日差

EN

Here is my code

        tvDatePicker = findViewById(R.id.textViewDate)
        btnDatePicker = findViewById(R.id.btn_datePicker)
        EndDatePicker = findViewById(R.id.textViewBookEnd)
        btnEndDatePicker = findViewById(R.id.btn_EndDatePicker)

        val myCalendar = Calendar.getInstance()
       
        val datePicker = DatePickerDialog.OnDateSetListener { _, year, month, dayOfMonth ->
            myCalendar.set(Calendar.YEAR,year)
            myCalendar.set(Calendar.MONTH,month)
            myCalendar.set(Calendar.DAY_OF_MONTH,dayOfMonth)
            updateStartDate(myCalendar)
        }

        val endDatePicker = DatePickerDialog.OnDateSetListener { _, year, month, dayOfMonth ->
            myCalendar.set(Calendar.YEAR,year)
            myCalendar.set(Calendar.MONTH,month)
            myCalendar.set(Calendar.DAY_OF_MONTH,dayOfMonth)
            updateEndDate(myEndCalendar)
        }

        btnDatePicker.setOnClickListener{
            DatePickerDialog(this,datePicker, myCalendar.get(Calendar.YEAR), myCalendar.get(Calendar.MONTH), myCalendar.get(Calendar.DAY_OF_MONTH)).show()
        }

        btnEndDatePicker.setOnClickListener{
            DatePickerDialog(this,endDatePicker, myCalendar.get(Calendar.YEAR), myCalendar.get(Calendar.MONTH), myCalendar.get(Calendar.DAY_OF_MONTH)).show()
        }

    private fun updateStartDate(myCalendar: Calendar){
        val myFormat = "dd-MM-yyyy"
        val sdf = SimpleDateFormat(myFormat, Locale.UK)
        tvDatePicker.setText(sdf.format(myCalendar.time))
    }

    private fun updateEndDate(myCalendar: Calendar){
        val myFormat = "dd-MM-yyyy"
        val sdf = SimpleDateFormat(myFormat, Locale.UK)
        EndDatePicker.setText(sdf.format(myCalendar.time))
    }