private SimpleDateFormat dateFormatMonth = new SimpleDateFormat("dd/MM/yyyy", Locale.getDefault());
Date date = dateFormatMonth.parse(strtdate[0]);
strdate[0]
contains "2018-06-11"
I'm getting a unparsable exception on this line:
java.text.ParseException: Unparseable date: "2018-06-11"
You are getting the error because you are using the wrong pattern to parse the date. Use this instead:
Assuming "06" is the month and "11" is day.