Java Data Type - 如何将String转换为dateTime并排序

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Main {
  public static void main(String[] args) throws Exception {
    SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd HH:mm:ss yyy");
    Date date1 = sdf.parse("Thu Oct 03 07:47:22 2015");
    Date date2 = sdf.parse("Mon Jul 05 08:47:22 2015");

    System.out.println(sdf.format(date1));
    System.out.println(sdf.format(date2));

    Calendar cal1 = Calendar.getInstance();
    Calendar cal2 = Calendar.getInstance();
    cal1.setTime(date1);
    cal2.setTime(date2);

    if (cal1.after(cal2)) {
      System.out.println("Date1 is after Date2");
    }

    if (cal1.before(cal2)) {
      System.out.println("Date1 is before Date2");
    }

    if (cal1.equals(cal2)) {
      System.out.println("Date1 is equal Date2");
    }
  }
}