Java Time Processing instance

1, in the use of SimpleDateFormat when the format of the time yyyy. MM.DD is a day of the year. If you want the format time to be 12-hour, use hh:mm:ss if you want the format time to be 24-hour, use HH:mm:ss

<span style= "White-space:pre" ></span>date d = new Date ();           SimpleDateFormat ss = new SimpleDateFormat ("Yyyy-mm-dd hh:mm:ss");//12-hour           System.out.println (Ss.format (d));            Date date = new Date ();           SimpleDateFormat Sdformat = new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");//24-hour           String lgtime = Sdformat.format ( Date);            

2. Time Calculation

DateFormat df=new SimpleDateFormat ("Yyyy-mm-dd EE hh:mm:ss");   System.out.println (Df.format (New Date ()));     Calendar C = calendar.getinstance ();     C.add (Calendar.month, 1); Current time plus 1 month   System.out.println (Df.format (C.gettime ()));     C.add (Calendar.hour, 3); Current time plus 3 hours   System.out.println (Df.format (C.gettime ()));     C.add (Calendar.year,-2); Current time minus 2 years   System.out.println (Df.format (C.gettime));     C.add (Calendar.day_of_week, 7); The current time adds 7 days   System.out.println (Df.format (C.gettime ()));   

3, take the first day of the month:

2. Java.text.SimpleDateFormat format = new java.text.SimpleDateFormat ("yyyy-mm-01");
4. Java.util.Date firstday=New java.util.Date ();
6. System.out.println ("The monthfirst day is" +formats.format (FirstDay));

4, take the last day of the month:

4. Calendar cal = Calendar.getinstance ();
6. int maxday=cals.getactualmaximum (calendar.day_of_month);
8. Java.text.Format formatter3=New Java.text.SimpleDateFormat ("yyyy-mm-"+maxday);
10. System.out.println (Formatter3.format (Cal.gettime ()));

5. Find the number of days between two dates:

2. Java.text.SimpleDateFormat format = new java.text.SimpleDateFormat ("YYYY-MM-DD");
4. Java.util.Date begindate= format.parse ("2007-12-24");
6. java.util.date enddate= format.parse" ( Span class= "string" style= "Color:blue" > "2007-12-25" );    
8. long day= (Date.gettime ()-mydate.gettime ())/(* ** +);
10. System.out.println ("number of days apart ="+day);

6, a year ago, the date:

2. Java.text.Format formatter=New Java.text.SimpleDateFormat ("YYYY-MM-DD");
4. java.util.date todaydate=new  java.util.date ();    
6. long  beforetime= (Todaydate.gettime ()/ 1000 ) -60 *60 *24 * 365 ;    
8. Todaydate.settime (beforetime*);
10. String Beforedate=formatter.format (todaydate);
12. System.out.println (beforedate);

7, one year after the date:

2. Java.text.Format formatter=New Java.text.SimpleDateFormat ("YYYY-MM-DD");
4. Java.util.Date todaydate=New java.util.Date ();
6. long  aftertime= (Todaydate.gettime ()/ 1000 ) +60 *60 *24 * 365 ;    
8. Todaydate.settime (aftertime*);
10. String Afterdate=formatter.format (todaydate);
12. System.out.println (afterdate);

8, 10 hours after the time

2. Java.util.Calendar cal=java.util.calendar.getinstance ();
4. Cal.settime (Dateoper);
6. Cal.add (Java.util.Calendar.HOUR_OF_DAY,ten);
8. System.out.println ("Date:"+forma.format (Cal.gettime ()));

9, 10 hours before the time

2. Java.util.Calendar cal=java.util.calendar.getinstance ();
4. Cal.settime (Dateoper);
6. Cal.add (java.util.calendar.hour_of_day,-);
8. System.out.println ("Date:"+forma.format (Cal.gettime ()));

Java Time Processing instance