SimpleDateFormat 简单使用

yyyy：年
MM：月
dd：日
hh：1~12小时制(1-12)
HH：24小时制(0-23)
mm：分
ss：秒
S：毫秒
E：星期几
D：一年中的第几天
F：一月中的第几个星期(会把这个月总共过的天数除以7)
w：一年中的第几个星期
W：一月中的第几星期(会根据实际情况来算)
a：上下午标识
k：和HH差不多，表示一天24小时制(1-24)。
K：和hh差不多，表示一天12小时制(0-11)。
z：表示时区 



Eg: yyyy-MM-dd HH:mm:ss

public void getFormatTime() {
        Date date = new Date();
        String strDateFormat = "yyyy-MM-dd HH:mm:ss";
        SimpleDateFormat sdf = new SimpleDateFormat(strDateFormat);
        System.out.println(sdf.format(date)); // 2021-03-27 21:13:23
   
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("hh:mm aa");
        simpleDateFormat.format(new Date(mRunTime));//11:00 AM
 }

1.获取手机时间(24小时、12小时制)自动转换

 //获取HH:mm 格式时间
    public String getFormatHourTime() {
        boolean is24HourFormat = DateFormat.is24HourFormat(getActivity());
        Calendar mCalendar = Calendar.getInstance();
        mCalendar.setTimeInMillis(System.currentTimeMillis());
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat(is24HourFormat ? "HH:mm" : "hh:mm aa");
        return simpleDateFormat.format(System.currentTimeMillis());
    }

2.获取当前时间(HH:mm)，不带秒

 //获取HH:mm:ss 格式时间
    public String getFormatCurrentTime() {
        @SuppressLint("SimpleDateFormat") SimpleDateFormat simpleDateFormat = new SimpleDateFormat("H:mm");
        return simpleDateFormat.format(new Date()) + ":00";
    }

3.判断是不是同一天

//判断是不是同一天
    public boolean isEqualHour(long mNewRunTime, long mOldRunTime) {
        Calendar old = Calendar.getInstance();
        old.setTimeInMillis(mNewRunTime);
        int i = old.get(Calendar.DAY_OF_MONTH);
        Calendar newca = Calendar.getInstance();
        newca.setTimeInMillis(mOldRunTime);
        int i1 = newca.get(Calendar.DAY_OF_MONTH);
        return i == i1;
    }

4.判断当前时间是否在startTime、EndTime之内

private static final String TIME_FORMAT_24 = "H:mm:ss";
//是否在两个时间之内(13:10:00)
    public boolean isStartTimeEndTimeBetween(String mCurrentTime, String mStartTime, String mEndTime) {
        if (TextUtils.isEmpty(mCurrentTime) || TextUtils.isEmpty(mStartTime) || TextUtils.isEmpty(mEndTime)) {
            return false;
        }
        @SuppressLint("SimpleDateFormat") SimpleDateFormat sdf1 = new SimpleDateFormat(TIME_FORMAT_24);
        @SuppressLint("SimpleDateFormat") SimpleDateFormat sdf2 = new SimpleDateFormat(TIME_FORMAT_24);
        @SuppressLint("SimpleDateFormat") SimpleDateFormat sdf3 = new SimpleDateFormat(TIME_FORMAT_24);
        Date currentDate;
        Date startDate;
        Date endDate;
        try {
            currentDate = sdf1.parse(mCurrentTime);
            startDate = sdf2.parse(mStartTime);
            endDate = sdf3.parse(mEndTime);
            if (currentDate == null || startDate == null || endDate == null) {
                return false;
            }
            long currentDateTime = currentDate.getTime();
            long startDateTime = startDate.getTime();
            long endDateTime = endDate.getTime();
            return currentDateTime >= startDateTime && currentDateTime <= endDateTime;
        } catch (ParseException e) {
            Log.i(TAG, "e: " + e.getMessage());
        }
        return false;
    }

5.获取今天是星期几

 Calendar mCalendar = Calendar.getInstance();
        mCalendar.setTimeInMillis(System.currentTimeMillis());
        int mWeek = mCalendar.get(Calendar.DAY_OF_WEEK);
        log.i("TAG","今天是周: "+daysOfWeek.contains(mWeek - 1));

6.判断开始时间是否大于结束时间

 private static final String TIME_FORMAT_24 = "H:mm:ss"; 
//开始是否大于结束时间（Eg:12:30:00）
    public boolean isStartThanEndTime(String mStartTime, String mEndTime) {
        if (TextUtils.isEmpty(mStartTime) || TextUtils.isEmpty(mEndTime)) {
            return false;
        }
        @SuppressLint("SimpleDateFormat") SimpleDateFormat sdf1 = new SimpleDateFormat(TIME_FORMAT_24);
        @SuppressLint("SimpleDateFormat") SimpleDateFormat sdf2 = new SimpleDateFormat(TIME_FORMAT_24);
        Date startDate;
        Date endDate;
        try {
            startDate = sdf1.parse(mStartTime);
            endDate = sdf2.parse(mEndTime);
            if (startDate == null || endDate == null) {
                return false;
            }
            long startDateTime = startDate.getTime();
            long endDateTime = endDate.getTime();
            return startDateTime > endDateTime;
        } catch (ParseException e) {
            Log.i(TAG, "e: " + e.getMessage());
        }
        return false;
    }

7. 24小时制转换12小时制(1:00 PM --> 13:00:00 )

 public String getConvert24Time(String mTime) {
        String mDateFormat = null;
        try {
            @SuppressLint("SimpleDateFormat") SimpleDateFormat mFormat = new SimpleDateFormat("HH:mm:ss");
            Date mDate = new SimpleDateFormat("hh:mm aa", Locale.US).parse(mTime);
            if (mDate == null) {
                return "";
            }
            mDateFormat = mFormat.format(mDate);
        } catch (ParseException e) {
            WpkLogUtil.i(TAG, "e: " + e.getMessage());
        }

        Log.i(TAG, "mDate: " + mDateFormat);
        return mDateFormat;
    }

8.12小时制转换24小时制(1:00 PM --> 13:00:00 )

 public String getConvert24Time(String mTime) {
        String mDateFormat = null;
        try {
            @SuppressLint("SimpleDateFormat") SimpleDateFormat mFormat = new SimpleDateFormat("HH:mm:ss");
            Date mDate = new SimpleDateFormat("hh:mm aa", Locale.US).parse(mTime);
            if (mDate == null) {
                return "";
            }
            mDateFormat = mFormat.format(mDate);
        } catch (ParseException e) {
            WpkLogUtil.i(TAG, "e: " + e.getMessage());
        }

        Log.i(TAG, "mDate: " + mDateFormat);
        return mDateFormat;
    }