java获取当前日期前三位，即星期几？

Question

import java.util.*;
public class ActionPlan
{
public static void main(String[] args)
{
Date date = new Date();
System.out.println(date);
String str =date;
String day = str.substring(0,3);
switch(day)
{
case"Monday":
System.out.println("ping-pong");
break;
case"Tuesday":
System.out.println("yoga");
break;
case"Wednesday":
System.out.println("swimming");
break;
case"Thursday":
System.out.println("tennis");
break;
case"Friday":
System.out.println("badminton");
break;
case"Saturday":
System.out.println("film");
break;
case"Sunday":
System.out.println("sleep");
break;

}
}
}

Answer 1

Calendar calendar = Calendar.getInstance();
SimpleDateFormat df = new SimpleDateFormat("yyyy-M-d");
String s = df.format(calendar.getTime());
System.out.println(s);
System.out.println(calendar.get(Calendar.DAY_OF_WEEK)-1);
因为星期是从周日开始的追问

当前日期输出是前三位是星期几，星期一就是Mon，星期二就是Tus，我就是想取这前三个字符，该怎么写？

追答

public static String getWeek(Date date){
SimpleDateFormat sdf = new SimpleDateFormat("EEEE");
String week = sdf.format(date);
return week;
}
main里，Date da=new Date();
System.out.println(getWeek(da));获取的是汉字星期几；
如果是英文的，你可以写个数组
String[] weeks = {"Sun","Mon","Tue","Wen","Thu","Fri","Sat"};
int index=calendar.get(Calendar.DAY_OF_WEEK)-1;
System.out.println(weeks[index-1]);