java获取当月天数，指定年月的天数，指定日期获取对应星期 . 





 1 package huolongluo.family.util;
 2 
 3 import java.text.SimpleDateFormat;
 4 import java.util.Calendar;
 5 import java.util.Date;
 6 
 7 /**
 8  * Created by 火龙裸 on 2018/7/13.
 9  */
10 
11 public class Number_Of_Days
12 {
13     /**
14      * 获取当月的 天数
15      */
16     public static int getCurrentMonthDay()
17     {
18         Calendar a = Calendar.getInstance();
19         a.set(Calendar.DATE, 1);
20         a.roll(Calendar.DATE, -1);
21         int maxDate = a.get(Calendar.DATE);
22         return maxDate;
23     }
24 
25     /**
26      * 根据 年、月 获取对应的月份 的 天数
27      */
28     public static int getDaysByYearMonth(int year, int month)
29     {
30         Calendar a = Calendar.getInstance();
31         a.set(Calendar.YEAR, year);
32         a.set(Calendar.MONTH, month - 1);
33         a.set(Calendar.DATE, 1);
34         a.roll(Calendar.DATE, -1);
35         int maxDate = a.get(Calendar.DATE);
36         return maxDate;
37     }
38 
39     /**
40      * 根据日期 找到对应日期的 星期几
41      *
42      * @param date 比如传参：2018-07-13 将返回“周五”
43      */
44     public static String getDayOfWeekByDate(String date)
45     {
46         String dayOfweek = "-1";
47         try
48         {
49             SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
50             Date myDate = myFormatter.parse(date);
51             SimpleDateFormat formatter = new SimpleDateFormat("E");
52             String str = formatter.format(myDate);
53             dayOfweek = str;
54         }
55         catch (Exception e)
56         {
57             System.out.println("错误!");
58         }
59         return dayOfweek;
60     }
61 }






 


这里添加另一个获取具体星期几的获取方法：




/**
 * 根据当前日期获得是星期几
 * time=yyyy-MM-dd
 * @return
 */
public static String getWeek(String time) {
    String Week = "";
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    Calendar c = Calendar.getInstance();
    try {
        c.setTime(format.parse(time));
    } catch (ParseException e) {
        e.printStackTrace();
    }

    int wek=c.get(Calendar.DAY_OF_WEEK);

    if (wek == 1) {
        Week += "星期日";
    }
    if (wek == 2) {
        Week += "星期一";
    }
    if (wek == 3) {
        Week += "星期二";
    }
    if (wek == 4) {
        Week += "星期三";
    }
    if (wek == 5) {
        Week += "星期四";
    }
    if (wek == 6) {
        Week += "星期五";
    }
    if (wek == 7) {
        Week += "星期六";
    }
    return Week;
}




 


 


补充一条，获取系统当前时间：


final DateFormat df = DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.MEDIUM);
String comment = "Added on " + df.format(new Date());
Log.e("当前时间为" + comment);

打印出来的格式为：xxxx年xx月xx日 xx:xx:xx






            

            
posted @ 
2017-04-12 01:01 
火龙裸先生 
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