import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.concurrent.TimeUnit;
 
public class Main {
	public static void main(String[] args) throws ParseException {
		String strDateStart = "2021-06-09";
		String strDateEnd = "2021-06-12";
 
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
		Date dateStart = sdf.parse(strDateStart);
		Date dateEnd = sdf.parse(strDateEnd);
 
		long millisInOneDay = TimeUnit.MILLISECONDS.convert(1, TimeUnit.DAYS);
		long days = Math.abs((dateEnd.getTime() - dateStart.getTime()) / millisInOneDay);
 
		System.out.println(days);
	}
}

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