Question

JAVA显示每月第一天星期几

import java.util.Scanner;public class Exercise {public static void main(String[] args){Scanner input=new Scanner(System.in);System.out.println("Enter the first day of a year");int firstDay=input.nextInt();System.out.println("Enter the year");int year=input.nextInt();int numberOfMonth=0;for(int month=1;month<=12;month++) {switch(month){case 1: System.out.print("January "+year+" is ");numberOfMonth=30;break;case 2: System.out.print("February "+year+" is ");if((year%4==0&&year%100!=0)||year%400==0)numberOfMonth=29;elsenumberOfMonth=28;break;case 3: System.out.print("March "+year+" is ");numberOfMonth=31;break;case 4: System.out.print("April "+year+" is ");numberOfMonth=30;break;case 5: System.out.print("May "+year+" is ");numberOfMonth=31;break;case 6: System.out.print("June "+year+" is ");numberOfMonth=30;break;case 7: System.out.print("July "+year+" is ");numberOfMonth=31;break;case 8: System.out.print("August "+year+" is ");numberOfMonth=31;break;case 9: System.out.print("September "+year+" is ");numberOfMonth=30;break;case 10: System.out.print("October "+year+" is ");numberOfMonth=31;break;case 11: System.out.print("November "+year+" is ");numberOfMonth=30;break;case 12: System.out.print("December "+year+" is ");numberOfMonth=31;break;}switch (firstDay) {case 0: System.out.println("Sunday"); break;case 1: System.out.println("Monday"); break;case 2: System.out.println("Tuesday"); break;case 3: System.out.println("Wednesday"); break;case 4: System.out.println("Thursday"); break;case 5: System.out.println("Friday"); break;case 6: System.out.println("Saturday"); break;}****** *****}}}末尾星号处有疑问，请见图，求解第一张图和第二张图中firstDay的变化过程和原因，为什么firstDay=firstDay+numberOfMonth打进去之后和第一张图的数据就不一样了？
错了，这是另一张





Answer 1

Calendar cal = Calendar.getInstance();
		cal.set(Calendar.DAY_OF_MONTH, cal.getActualMinimum(Calendar.DAY_OF_MONTH));
		System.out.println(cal.get(Calendar.YEAR)+" "+(cal.get(Calendar.MONTH)+1)+" "+cal.get(Calendar.DAY_OF_MONTH)+" ");
		int i = cal.get(Calendar.DAY_OF_WEEK);
		String[] str = {"","SUNDAY","MONDAY","TUESDAY","WEDNESDAY","THURSDAY","FRIDAY" ,"SATURDAY"};
		System.out.println(str[i]);

运行结果：

2016 7 1 

FRIDAY

说明：

Calendar的getActualMinimum
(int field)他传入的是一个int类型，这个方法的具体意思就是说根据你传入的参数代表的意思（年、月、周等）查询当前（年、月、周）拥有的最小值。

另外：

Calendar的getActualMaximum(int field)他传入的是一个int类型，这个方法的具体意思就是说根据你传入的参数代表的意思（年、月、周等）查询当前（年、月、周）拥有的最大值。

Answer 2

你这两张图 一样啊.......

追问

哦哦哦错了错了，现在换

追答

代码粘的不太全啊 私信我 我帮你看看
.....不发私信是吧？行吧 我硬推
上段代码中的两行输出和下段代码的一行输出 跟输出英文月份 完全没有关系
仅仅是输出一个数值
而上段代码有效的原因很可能是因为在第47行修改了firstDay的值 并且输出英文月份是依赖这个值的
下段代码没有对firstDay做任何操作 所以 无效