Java判断时间是否为半夜(23:59与00:01之间)及常用时间比较方法

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 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 map = new HashMap();        map.put("startdate", startdate);        map.put("enddate", enddate);        return map;    }