本文主要介绍Java中判断时间是否半夜的方法,具体指的是半夜12点正负一分钟,也就是23:59与00:01之间。以及时间比较的方法 。

1、错误代码

private final LocalTime ONE_MINUTE_BEFORE_MIDNIGHT = LocalTime.of(23, 59, 0);
private final LocalTime ONE_MINUTE_AFTER_MIDNIGHT = LocalTime.of(0, 1, 0);
public boolean isAtMidnight(LocalTime time) { return time.isAfter(ONE_MINUTE_BEFORE_MIDNIGHT) && time.isBefore(ONE_MINUTE_AFTER_MIDNIGHT); }

上面代码有问题,总是返回False,这里要特别注意不能使用&&符号。

2、正确代码

public boolean isAtMidnight(LocalTime time){
return time.isAfter(ONE_MINUTE_BEFORE_MIDNIGHT) || time.isBefore(ONE_MINUTE_AFTER_MIDNIGHT);
}
public static void main(String[] args) { LocalTime ONE_MINUTE_BEFORE_MIDNIGHT = LocalTime.of(23, 59, 0); LocalTime ONE_MINUTE_AFTER_MIDNIGHT = LocalTime.of(0, 1, 0); LocalTime md = LocalTime.MIDNIGHT; System.out.println(md.isBefore(ONE_MINUTE_AFTER_MIDNIGHT) || md.isAfter(ONE_MINUTE_BEFORE_MIDNIGHT)); }

3、时间比较方法

1)两个string类型的日期比较大小

public static int compare_date(String DATE1, String DATE2) {
DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
Date dt1 = df.parse(DATE1);
Date dt2 = df.parse(DATE2);
if (dt1.getTime() > dt2.getTime()) {
System.out.println("dt1 在dt2前");
return 1;
} else if (dt1.getTime() < dt2.getTime()) {
System.out.println("dt1在dt2后");
return -1;
} else {
return 0;
}
} catch (Exception exception) {
exception.printStackTrace();
}
return 0;
}

2)返回两个string类型日期之间相差的天数

public static int daysBetween(String smdate,String bdate){  
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
Calendar cal = Calendar.getInstance();
long time1 = 0;
long time2 = 0;
try{
cal.setTime(sdf.parse(smdate));
time1 = cal.getTimeInMillis();
cal.setTime(sdf.parse(bdate));
time2 = cal.getTimeInMillis();
}catch(Exception e){
e.printStackTrace();
}
long between_days=(time2-time1)/(1000*3600*24);
return Integer.parseInt(String.valueOf(between_days));
}

3)返回两个string类型日期相差的小时数

public static int daysBetween2(String startTime, String endTime) {
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH");
Calendar cal = Calendar.getInstance();
long time1 = 0;
long time2 = 0;
try{
cal.setTime(sdf.parse(startTime));
time1 = cal.getTimeInMillis();
cal.setTime(sdf.parse(endTime));
time2 = cal.getTimeInMillis();
}catch(Exception e){
e.printStackTrace();
}
long between_days=(time2-time1)/(1000*3600);
return Integer.parseInt(String.valueOf(between_days));
}

4)计算两段日期的重合日期

/**
     * 计算两段日期的重合日期
     * @param str1 开始日期1
     * @param str2 结束日期1
     * @param str3 开始日期2
     * @param str4 结束日期2
     * @return
     * @throws Exception
     */
    public static Map<String,Object> comparisonRQ(String str1, String str2, String str3,
            String str4) throws Exception {
        String mesg = "";
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        String startdate = "";
        String enddate = "";
        try {
            Date dt1 = df.parse(str1);
            Date dt2 = df.parse(str2);
            Date dt3 = df.parse(str3);
            Date dt4 = df.parse(str4);
            if (dt1.getTime()<=dt3.getTime()&&dt3.getTime()<=dt2.getTime()&&dt2.getTime()<=dt4.getTime()) {
                mesg = "f";//重合
                startdate = str3;
                enddate = str2;
            }
            if (dt1.getTime()>=dt3.getTime()&&dt3.getTime()<=dt2.getTime()&&dt2.getTime()<=dt4.getTime()) {
                mesg = "f";//重合
                startdate = str1;
                enddate = str2;
            }
            if (dt3.getTime()<=dt1.getTime()&&dt1.getTime()<=dt4.getTime()&&dt4.getTime()<=dt2.getTime()) {
                mesg = "f";//重合
                startdate = str1;
                enddate = str4;
            }
            if (dt3.getTime()>=dt1.getTime()&&dt1.getTime()<=dt4.getTime()&&dt4.getTime()<=dt2.getTime()) {
                mesg = "f";//重合
                startdate = str3;
                enddate = str4;
            }
            System.out.println(startdate+"----"+enddate);
        }catch (ParseException e) {
            e.printStackTrace();
            throw new ParseException(e.getMessage(), 0);
        }catch(Exception e){
            e.printStackTrace();
            throw new Exception(e);
        }
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("startdate", startdate);
        map.put("enddate", enddate);
        return map;
    }