【发布时间】：2016-02-28 07:17:03
【问题描述】：
我目前正在做一个问题集，我必须创建一个日历来显示一年中的所有月份，包括其中的日期。但是，我对每个月第一行的间距有疑问。在课堂上我们只学习了 switch 语句，if、else、while、do-while、for 循环
这是我的一个月中当前显示的内容：
Image of output 图片中没有显示我的输入，但我写的是 2016 年和 5 年开始的工作日。
Image of output of what what is desired 再一次，一张想要的照片。我认为我的问题可能是我使用的方程式： int firstDayEachMonth = (daysMonth + firstDayYear)%7;虽然老师把这个方程给我们用了，但是好像不行。
如您所见，第一行的空格一直在左边，它应该与指定的日期对齐，在这种情况下为 1 月，1 月 1 日应与周五对齐，1 月 2 日应与周六对齐，但目前是周日和周一。
import java.util.Scanner;
public class DisplayCalendar
{
public static void main(String[] args)
{
//Create a new scanner
Scanner input = new Scanner(System.in);
// Prompt user to enter year
System.out.print("Enter a year: ");
int year = input.nextInt();
// Prompt user to enter first day of the year
System.out.print("Enter the weekday that the year starts: ");
int firstDayYear = input.nextInt();
// A for loop that prints out each month
for(int month = 1; month <= 12; month++)
{
// Set the value of the amount of days in a month
int daysMonth = 0;
// Set value of the month
String monthDisplay = "";
// Find name of each month and number of days
switch(month)
{
case 1: monthDisplay = "January";
daysMonth = 31;
break;
case 2:
monthDisplay = "February";
int leapYear = 0;
while (leapYear > -1)
{
// Count all years that are divisible by 4 to be a leap year.
leapYear += 4;
// If the year inputted is a leap year, the days of the month will be 29.
if (year == leapYear)
{
daysMonth = 29;
break;
}
else
{
daysMonth = 28;
}
}
break;
case 3: monthDisplay = "March";
daysMonth = 31;
break;
case 4: monthDisplay = "April";
daysMonth = 30;
break;
case 5: monthDisplay = "May";
daysMonth = 31;
break;
case 6: monthDisplay = "June";
daysMonth = 30;
break;
case 7: monthDisplay = "July";
daysMonth = 31;
break;
case 8: monthDisplay = "August";
daysMonth = 31;
break;
case 9: monthDisplay = "September";
daysMonth = 30;
break;
case 10: monthDisplay = "October";
daysMonth = 31;
break;
case 11: monthDisplay = "November";
daysMonth = 30;
break;
case 12: monthDisplay = "December";
daysMonth = 31;
break;
// If the month is not recognized, dialog box will be displayed, and then exits program.
default : System.out.print("Invalid: Your month is not recognized. ");
System.exit(0);
}
// Display the month and year
System.out.println(" "+ monthDisplay + " " + year);
// Display the lines
System.out.println("_____________________________________");
// Display the days of the week
System.out.println("Sun Mon Tue Wed Thu Fri Sat");
// Print spaces depending on the day the month starts.
int firstDayEachMonth = (daysMonth + firstDayYear)%7;
for (int space = 1; space <= firstDayEachMonth; space++)
System.out.print(" ");
// Print the days
for (int daysDisplay = 1; daysDisplay <= daysMonth; daysDisplay++)
{
if (firstDayYear%7 == 0)
System.out.println();
System.out.printf("%3d ", daysDisplay);
firstDayYear += 1;
}
System.out.println();
}
}
}
我们不能使用不同的库（如Calendar），只能使用扫描仪。
【问题讨论】：
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假设这是家庭作业，您是否可以查看标准 Java 库和 API？如果你是，java.util.Calendar 和 java.lang.String.format 可能会感兴趣。特别是，Calendar.roll 将帮助您完成大量工作......
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嘿，我们不能使用不同的库，只能使用扫描仪。