Android应用中怎么对时间进行获取

import java.text.DateFormat;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class GetTime {  public static void main(String[] args) {    Date date = new Date();    System.out.println(date);//Mon May 08 14:27:44 CST 2017    System.out.println(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(date));//2017-05-08 02:27:44    long millis = System.currentTimeMillis();    System.out.println(millis);//1494224864479    System.out.println(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(millis));//2017-05-08 02:27:44    //yyyy-MM-dd  E  hh:mm:ss.sss    //年-月-日   星期  时:分:秒.毫秒    System.out.println(new SimpleDateFormat("yyyy-MM-dd E hh:mm:ss.sss").format(date));//2017-05-08 星期一 02:27:44.044    System.out.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.sss").format(date));//2017-05-08 14:27:44.044    System.out.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date));//2017-05-08 14:27:44    System.out.println(new SimpleDateFormat("yyyy-MM-dd HH:mm").format(date));//2017-05-08 14:27    System.out.println(new SimpleDateFormat().format(date));//17-5-8 下午2:27 :默认    compareDataToNow("2017-05-03 12:45:00");    try {      Date date1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2017-05-03 12:45:00");      compareToNowDate(date1);    } catch (ParseException e) {      e.printStackTrace();    }    getWeek();    getTime1();    getTime2();  }  static void getTime1() {    long time = System.currentTimeMillis();    //long now = android.os.SystemClock.uptimeMillis();    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");    Date d1 = new Date(time);    String t1 = format.format(d1);    System.out.println("SimpleDateFormat时间===" + t1);//2017-05-08 12:44:10    SimpleDateFormat f4 = new SimpleDateFormat("今天是" + "yyyy年MM月dd日 E kk点mm分");    System.out.println("f4======" + f4.format(new Date()));//今天是2017年05月08日 星期一 14点15分    SimpleDateFormat f3 = new SimpleDateFormat("今天是" + "hh小时mm分钟");    System.out.println("f3======" + f3.format(new Date()));//今天是02小时15分钟    SimpleDateFormat f2 = new SimpleDateFormat("今天是" + "kk点mm分钟");    System.out.println("f2======" + f2.format(new Date()));//今天是14点17分钟  }  static void getTime2() {    Calendar calendar = Calendar.getInstance();    String created = calendar.get(Calendar.YEAR) + "年"        + (calendar.get(Calendar.MONTH) + 1) + "月"//从0计算        + calendar.get(Calendar.DAY_OF_MONTH) + "日"        + calendar.get(Calendar.HOUR_OF_DAY) + "时"        + calendar.get(Calendar.MINUTE) + "分" + calendar.get(Calendar.SECOND) + "s";    System.out.println("Calendar时间====" + created);//时间：2017年5月8日12时33分24s  }  static void getWeek() {    Calendar calendar = Calendar.getInstance();    int day = calendar.get(Calendar.DAY_OF_WEEK);    String today = null;    if (day == 2) {      today = "Monday";    } else if (day == 3) {      today = "Tuesday";    } else if (day == 4) {      today = "Wednesday";    } else if (day == 5) {      today = "Thursday";    } else if (day == 6) {      today = "Friday";    } else if (day == 7) {      today = "Saturday";    } else if (day == 1) {      today = "Sunday";    }    System.out.println("Today is:- " + today);//Today is:- Monday  }  //计算日期之间相隔几天：  static long compareDataToNow(String date) {    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");    Date passDate, nowDate;    long diff = -100l, days = -100l;    try {      passDate = sdf.parse(date);      String nowStr = sdf.format(new Date());      nowDate = sdf.parse(nowStr);      diff = passDate.getTime() - nowDate.getTime();//long型的毫秒数      days = diff / (1000 * 60 * 60 * 24);      System.out.println("相隔：" + days + "天" + " nowDate.getTime()=====" + nowDate.getTime());//-5天    } catch (ParseException e) {      e.printStackTrace();    }    return diff;  } //计算日期之间相隔几天：  static long compareToNowDate(Date date) {    long diff = -100l, days = -100l;    Date nowDate = new Date();    diff = date.getTime() - nowDate.getTime();//long型的毫秒数    days = diff / (1000 * 60 * 60 * 24);    System.out.println("相隔：" + days + "天" + " nowDate.getTime()=====" + nowDate.getTime());//-5天    return diff;  }}