我目前正在设置一个问题集，我必须创建一个显示一年中所有月份的日历，包括其中每月的日期。但是我每个月第一行的间距都有问题。在课堂上，我们只学习了switch语句，if，else，while，do-while，for loops
以下是我目前的一个月内显示的内容：
Image of output 在图中并没有显示我的输入，但我写的是今年的2016年和今年开始的工作日的5。
Image of output of what what is desired 再次，描绘了所需的图片。我认为我的问题可能是我使用的方程式：int firstDayEachMonth =（daysMonth + firstDayYear）％7;虽然老师给我们这个等式使用，但似乎它不起作用。
正如你所看到的那样，第一行的空格一直是左边的，它应该与指定的日期对齐，在这种情况下，1月，1月1日应该对齐星期五，1月2日应该与星期六对齐但是它目前在周日和周一。
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();
}
}
}
答案 0 :(得分：1)
你能试试这个例子吗？ 我可以看到以下输出：
February 2016
Sun Mon Tue Wed Thu Fri Sat
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29
package general;
import java.util.Scanner;
public class DisplayCalendar {
public static void main(String[] args) {
int Y = 2016; // year
int startDayOfMonth = 5;
int spaces = startSayOfMonth;
// months[i] = name of month i
String[] months = {
"", // leave empty so that we start with months[1] = "January"
"January", "February", "March",
"April", "May", "June",
"July", "August", "September",
"October", "November", "December"
};
// days[i] = number of days in month i
int[] days = {
0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
for (int M = 1; M <= 12; M++) {
// check for leap year
if ((((Y % 4 == 0) && (Y % 100 != 0)) || (Y % 400 == 0)) && M == 2)
days[M] = 29;
// print calendar header
// Display the month and year
System.out.println(" "+ months[M] + " " + Y);
// Display the lines
System.out.println("_____________________________________");
System.out.println(" Sun Mon Tue Wed Thu Fri Sat");
// spaces required
spaces = (days[M-1] + spaces)%7;
// print the calendar
for (int i = 0; i < spaces; i++)
System.out.print(" ");
for (int i = 1; i <= days[M]; i++) {
System.out.printf(" %3d ", i);
if (((i + spaces) % 7 == 0) || (i == days[M])) System.out.println();
}
System.out.println();
}
}
}
答案 1 :(得分：1)
由于这似乎是一项家庭作业，因此我不会费心为您提供正确的算法。那会破坏您或其他有相同问题的人的目的，即练习您的编程和分析技能。
在这一行for (int space = 1; space <= firstDayEachMonth; space++)中，您可以完全忽略firstDayEachMonth的结果，并使用firstDayYear计数器。该计数器具有一年中的开始工作日，并且每天过去时都会递增。另外，有必要定义您的一周是从0还是1开始。
在这一部分中，您已经在以下位置设置了周末的换行符：
if (firstDayYear%7 == 0)
System.out.println();
当您遇到这种情况时，我会重置firstDayYear，因为既然您将它用作设置空间的参数，那么这个数字就永远不会大于7。这样，您就可以安排每周的工作日正确地放在日历上，唯一的问题是将其以正确的格式显示在屏幕上。
当您像这样System.out.println("Sun Mon Tue Wed Thu Fri Sat");打印星期几标题时，请记住您的名称的长度为3加5空格。因此，此行System.out.printf("%3d ", daysDisplay);应该有一个宽度为3个空格的数字，这说明了%3d的使用以及5个空格。在这种情况下，您有6个空格，总是给您错误的偏移量，并且会在某些行上引起麻烦。
这些是我注意到的事情，希望对您有所帮助。和平！
答案 2 :(得分：1)
我建议您使用 modern Date-Time API*，它自 Java SE 8 以来一直是标准库的一部分。
import java.time.LocalDate;
import java.time.YearMonth;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// Test harness
Scanner input = new Scanner(System.in);
System.out.print("Please enter a month between 1 and 12 (e.g. 5): ");
int m = input.nextInt();
System.out.print("Please enter a full year (e.g. 2018): ");
int y = input.nextInt();
printMonth(y, m);
}
static void printMonth(int year, int month) {
YearMonth ym = YearMonth.of(year, month);
System.out.println("Sun Mon Tue Wed Thu Fri Sat");
int counter = 1;
// Get day of week of 1st date of the month and print space for as many days as
// distant from SUN
int dayValue = LocalDate.of(year, month, 1).getDayOfWeek().getValue();
if (dayValue != 7)
for (int i = 0; i < dayValue; i++, counter++) {
System.out.printf("%-4s", "");
}
for (int i = 1; i <= ym.getMonth().length(ym.isLeapYear()); i++, counter++) {
System.out.printf("%-4d", i);
// Break the line if the value of the counter is multiple of 7
if (counter % 7 == 0) {
System.out.println();
}
}
}
}
示例运行：
Please enter a month between 1 and 12 (e.g. 5): 9
Please enter a full year (e.g. 2018): 2020
Sun Mon Tue Wed Thu Fri Sat
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30
从 Trail: Date Time 了解有关现代 Date-Time API 的更多信息。
* 出于任何原因，如果您必须坚持使用 Java 6 或 Java 7，您可以使用 ThreeTen-Backport，它将大部分 java.time 功能向后移植到 Java 6 & 7. 如果您正在为 Android 项目工作并且您的 Android API 级别仍然不符合 Java-8，请检查 Java 8+ APIs available through desugaring 和 How to use ThreeTenABP in Android Project。
答案 3 :(得分：0)
public class Exercice5_29DisplayCalenderDay {
/**
* @param args the command line arguments
*/
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.println("Enter the weekday that the year starts: ");
int day = input.nextInt();
int dayCounter = day;
int nbrOfDays = 0;
String monthx = "";
for (int month= 1; month <=12; month++)
{
// Switch to chose the month
switch (month)
{
case 1: monthx = "January";
nbrOfDays = 31;
break;
case 2: monthx = "February";
if ( year % 4 == 0 && year % 100 !=0 || year % 400 == 0)
{
nbrOfDays = 29;
break;
}
else
{ nbrOfDays = 28;
break;
}
case 3: monthx = "March";
nbrOfDays = 31;
break;
case 4: monthx = "April";
nbrOfDays = 30;
break;
case 5: monthx = "May";
nbrOfDays = 31;
break;
case 6: monthx = "June";
nbrOfDays = 30;
break;
case 7: monthx = "July";
nbrOfDays = 31;
break;
case 8: monthx = "August";
nbrOfDays = 31;
break;
case 9: monthx = "September";
nbrOfDays = 30;
break;
case 10: monthx = "October";
nbrOfDays = 31;
break;
case 11: monthx = "November";
nbrOfDays = 30;
break;
case 12: monthx = "December";
nbrOfDays = 31;
break;
}
System.out.printf("%15s %d \n", monthx , year);
System.out.println("----------------------------");
System.out.printf("%s %s %s %s %s %s %s\n ", "Sun","Mon","Tue", "Wed", "Thu","Fri","Sat");
for (int space =1; space<=day; space++)
{
System.out.printf("%4s", " ");
}
for (int i = 1; i <=nbrOfDays; i++)
{
dayCounter++;
if ( dayCounter% 7==0)
System.out.printf("%- 4d\n", i);
else
System.out.printf("%-4d", i);
}
day = (day + nbrOfDays)%7;
System.out.println();
}
}
}
答案 4 :(得分：0)
导入java.util.Scanner;
公共类DisplayCalendar {
public static void main(String[] args) {
String Months[] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
int numday[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
Scanner in = new Scanner(System.in);
System.out.println("enter the year");
int year = in.nextInt();
if ((((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0))) {
numday[1] = 29;
}
System.out.println("enter the day start the year ");
int day = in.nextInt();
for (int i = 1; i <= 12; i++) {
System.out.println("\t" + Months[i - 1]+" "+ year);
System.out.println("ـــــــــــــــــــــــــ");
System.out.printf("%-4s%-4s%-4s%-4s%-4s%-4s%-4s\n","Sun","Mon","Tue","Wed","Thu","Fri","Sat");
day = manh(day, numday[i - 1]);
}
}
public static int manh(int day, int numday) {
int a[][] = new int[6][7];
int counter = 1;
int j = 0;
for (int i = 0; i < 6; i++) {
for (j = day; j < 7; j++) {
a[i][j] = counter;
day++;
counter++;
if (counter == numday + 1) {
break;
}
}
day = 0;
if (counter == numday + 1) {
break;
}
}
for (int i = 0; i < 6; i++) {
for (int f = 0; f < 7; f++) {
System.out.printf("%-4s", a[i][f] == 0 ? "" : a[i][f]);
}
System.out.println();
}
int dayret = j + 1;
return dayret >= 7 ? 0 : dayret;
}
}