Practical summary of java date and SimpleDateFormat

package com.cn.ssyan.study;

import java.util.Date;
import java.util.Random;
import java.text.*;

public class Datetest {
public static void main(String[] args) throws ParseException {
howgetdate();
}

public static void howgetdate() throws ParseException {
// Date newdate = new Date();// Date
SimpleDateFormat newformat = new SimpleDateFormat("yyyy-MM-dd");// Date to character
// String mydate = newformat.format (newdate);// Generate date newdate to character mydate
String begin_date = "2016-01-01";
String end_date = "2016-03-01";
// System.out.println(newdate);
// System.out .println(newformat);
// System.out.println(mydate);
while (begin_date.compareTo(end_date) < 0) {
String[] subs = { "500kV Hongyang Transformer", "500kV Yangxing Transformer", " 500kV Xuxing Transformer", "500kV Huangdu Transformer", "500kV Sijing Transformer", "500kV Xinyu Transformer", "500kV Liantang Transformer",
"500kV South Bridge Transformer", "500kV Tingwei Transformer", "500kV Far East Transformer" , "500kV Sanlin Substation", "500kV Jing'an Substation", "500kV Yanggao Substation", "500kV Gulu Substation" };
String[] alarm = { "Accident Alarm", "Abnormal Alarm", "Displacement Alarm", " Notify alarm", "Over-limit alarm" };
String outdate = begin_date;
Random rand = new Random();
int a = rand.nextInt(7);
int b = rand.nextInt(subs.length);
int c = rand.nextInt(7);
int d = rand.nextInt(alarm.length);
// for (int i = 0; i < subs.length; i++) {
// System.out.println(outdate + ' ' + subs[i]);
// }
// System.out.println(outdate + ' ' + subs[b]);
begin_date = newformat.format(new Date(newformat.parse(begin_date).getTime() + 60*60* 24*1000*a));
String one_date = newformat.format(new Date(newformat.parse(begin_date).getTime() + 60*60* 24*1000*c));
System.out.println("发生时间："+outdate +" "+ subs[b]+"-"+alarm[d]+" "+"结束时间："+one_date);
}
}

}