使用Java打印12个月的年份和接下来的2年
使用Java打印12个月的年份和接下来的2年
提问于 2019-05-20 09:27:34
对于这个已经有了一个初始的程序，我使代码尽可能的简短和精确。但经过检查，似乎未来两年仍然是2018年，我预计2019年和2020年。当显示2018、2019和2020年时，如何动态打印年份？可能我在代码中遗漏了一些迭代。
您也可以随意批评我的代码，您也可以尽可能多地使用Calendar API或Java 8实用程序来建议更短的代码。
请看下面的代码：
package calendarjava;
import java.util.Calendar;
import java.util.Scanner;
import java.util.GregorianCalendar;
import java.util.Locale;
public class CalendarJava {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("Enter a year: ");
int year = sc.nextInt();
Calendar cal = new GregorianCalendar();
int startDay;
int numberOfDays;
for (int i=0; i<36; i++){
cal.set(year, i, 1);
startDay = cal.get(Calendar.DAY_OF_WEEK);
numberOfDays = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
System.out.print(cal.getDisplayName(Calendar.MONTH, Calendar.LONG, Locale.US));
System.out.println( " " + year);
printMonth(numberOfDays,startDay);
System.out.println();
}
}
private static void printMonth(int numberOfDays, int startDay) {
int weekdayIndex = 0;
System.out.println("Su Mo Tu We Th Fr Sa");
for (int day = 1; day < startDay; day++) {
System.out.print(" ");
weekdayIndex++;
}
for (int day = 1; day <= numberOfDays; day++) {
System.out.printf("%1$2d", day);
weekdayIndex++;
if (weekdayIndex == 7) {
weekdayIndex = 0;
System.out.println();
} else {
System.out.print(" ");
}
}
System.out.println();
}
}Enter a year: 2018
January 2018
Su Mo Tu We Th Fr Sa
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 31
February 2018
Su Mo Tu We Th Fr Sa
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
March 2018
Su Mo Tu We Th Fr Sa
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 31
April 2018
Su Mo Tu We Th Fr Sa
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
May 2018
Su Mo Tu We Th Fr Sa
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 31
June 2018
Su Mo Tu We Th Fr Sa
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
July 2018
Su Mo Tu We Th Fr Sa
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 31
August 2018
Su Mo Tu We Th Fr Sa
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 31
September 2018
Su Mo Tu We Th Fr Sa
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
October 2018
Su Mo Tu We Th Fr Sa
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 31
November 2018
Su Mo Tu We Th Fr Sa
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
December 2018
Su Mo Tu We Th Fr Sa
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 31
January 2018
Su Mo Tu We Th Fr Sa
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 31
February 2018
Su Mo Tu We Th Fr Sa
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
March 2018
Su Mo Tu We Th Fr Sa
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
31
April 2018
Su Mo Tu We Th Fr Sa
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
May 2018
Su Mo Tu We Th Fr Sa
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 31
June 2018
Su Mo Tu We Th Fr Sa
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
July 2018
Su Mo Tu We Th Fr Sa
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 31
August 2018
Su Mo Tu We Th Fr Sa
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 31
September 2018
Su Mo Tu We Th Fr Sa
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
October 2018
Su Mo Tu We Th Fr Sa
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 31
November 2018
Su Mo Tu We Th Fr Sa
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
December 2018
Su Mo Tu We Th Fr Sa
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 31
January 2018
Su Mo Tu We Th Fr Sa
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 31
February 2018
Su Mo Tu We Th Fr Sa
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
March 2018
Su Mo Tu We Th Fr Sa
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 31
April 2018
Su Mo Tu We Th Fr Sa
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
May 2018
Su Mo Tu We Th Fr Sa
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
31
June 2018
Su Mo Tu We Th Fr Sa
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
July 2018
Su Mo Tu We Th Fr Sa
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 31
August 2018
Su Mo Tu We Th Fr Sa
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 31
September 2018
Su Mo Tu We Th Fr Sa
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
October 2018
Su Mo Tu We Th Fr Sa
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 31
November 2018
Su Mo Tu We Th Fr Sa
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
December 2018
Su Mo Tu We Th Fr Sa
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 31回答 1
Stack Overflow用户
回答已采纳
发布于 2019-05-20 12:55:57
现代Java
这里有一个完全不同的观点，供您比较。这段代码使用了现代Java语言的特性，包括在JSR 310中定义的类、streams、便捷的List factory方法和enums。
为了定义我们的CalendarMaker类，所有这些代码都包含在一个.java文件中。有关如何使用此类的演示，请参阅main方法。
该类有两个通过构造函数注入的成员变量:一个是要在结果文本中使用的end-of-line (newline)字符，另一个是Locale，我们通过它(a)确定星期几的顺序，(b)本地化月份的名称和星期几的名称。
我们使用StringBuilder类通过调用它的append方法来构建文本。
尽可能使用特定的类型，以使您的代码更具self-documenting，确保有效的值，并提供type-safety。因此，我们从本年度以及前几年和后几年的Year对象列表开始。
对于每一年，我们循环月份。每个月都表示为一个YearMonth对象。我们通过调用Month.getDisplayName来本地化月份的名称。然后，我们通过首先本地化星期几的名称来本地化星期几列标题，然后截断以只接受前两个字母。
DayOfWeek枚举提供现成的对象来表示一周中的每一天。
请注意，我们还本地化了一周中各天的顺序。在美国，大多数历法都是从星期天开始一周。但在欧洲和其他地方，你通常会先看到周一。我们的代码允许一周中的任何一天开始一周，以防某些文化规范有其他选择。
在TemporalAdjusters类中找到的TemporalAdjuster决定了我们的每月网格中的开始日期。然后我们一天一天地递增，以每周为单位。或者，我们禁止显示超出目标月份的日期。
要生成每个日期的文本，请使用DateTimeFormatter。使用dd格式模式用零填充一位数数字。要填充空格，请使用ppd。
更新:我用来自LocalDate.datesUntil的流替换了这段代码中的for循环。在内部，我们使用ternary operator来抑制目标月份之外的日期。我并不是说这种重写一定更好；我只是想以stream & lambda作为现代Java编程的一个例子来展示其精妙的语法。
// Rows (each week)
LocalDate localDate = yearMonth.atDay( 1 ).with( TemporalAdjusters.previousOrSame( firstDayOfWeek ) );
while ( ! localDate.isAfter( yearMonth.atEndOfMonth() ) ) // "Not after" is a shorter way of saying "is equal to or sooner than".
{
for ( int i = 0 ; i < 7 ; i++ )
{
// If we want to suppress the out-of-month dates that may exist in first and last rows.
if ( ! YearMonth.from( localDate ).equals( yearMonth ) )
{
sb.append( " " ); // Use 2 spaces rather than 2 digits of day-of-month number.
} else // Else the date is inside our target year-month.
{
sb.append( localDate.format( CalendarMaker.DAY_FORMATTER ) );
}
if ( i < 6 )
{
sb.append( " " ); // Pad with a SPACE between columns.
}
localDate = localDate.plusDays( 1 ); // Increment one day at a time.
}
sb.append( this.eol );
}…变成了：
// Rows (each week)
LocalDate localDate = yearMonth.atDay( 1 ).with( TemporalAdjusters.previousOrSame( firstDayOfWeek ) ); // Get the first date of the month, then move backwards in time to determine the first date that fits our calendar grid. May be the same as the first, or may be earlier date from the previous month.
while ( ! localDate.isAfter( yearMonth.atEndOfMonth() ) ) // "Not after" is a shorter way of saying "is equal to or sooner than".
{
String week =
localDate
.datesUntil( localDate.plusWeeks( 1 ) ) // Get a stream of dates via `LocalDate::datesUntil`. The ending date is exclusive (half-open).
.map( ld -> ( YearMonth.from( ld ).equals( yearMonth ) ? ld.format( CalendarMaker.DAY_FORMATTER ) : " " ) ) // Display the day-of-month number if within the target month, otherwise display a pair of SPACE characters.
.collect( Collectors.joining( " " ) ); // Separate columns with a SPACE in our calendar grid.
sb.append( week ).append( this.eol ); // Add this row of text for the week, and wrap to next line for next loop.
localDate = localDate.plusWeeks( 1 ); // Increment one week at a time to set up our next loop.
}CalendarMaker.java
package work.basil.example;
import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.format.TextStyle;
import java.time.temporal.TemporalAdjusters;
import java.time.temporal.WeekFields;
import java.util.EnumSet;
import java.util.List;
import java.util.Locale;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
public class CalendarMaker
{
// Member variables.
private String eol;
private Locale locale;
static private DateTimeFormatter DAY_FORMATTER = DateTimeFormatter.ofPattern( "ppd" ); // Use `dd` to pad single-digits values with a leading zero. Use `ppd` to pad with a SPACE.
// Constructor
public CalendarMaker ( String eol , Locale locale )
{
this.eol = eol;
this.locale = locale;
}
private CharSequence generateYear ( final Year year )
{
// Year header.
StringBuilder sb = new StringBuilder();
sb.append( "|------ " + year + " ------|" ).append( this.eol ).append( this.eol );
// Each month.
for ( Month month : EnumSet.allOf( Month.class ) )
{
YearMonth ym = YearMonth.of( year.getValue() , month );
CharSequence monthCalendar = this.generateMonth( ym );
sb.append( monthCalendar );
}
return sb;
}
private CharSequence generateMonth ( final YearMonth yearMonth )
{
// Title
StringBuilder sb = new StringBuilder();
String monthName = yearMonth.getMonth().getDisplayName( TextStyle.FULL , this.locale );
sb.append( yearMonth.getYear() ).append( " " ).append( monthName ).append( this.eol );
// Column headers.
DayOfWeek firstDayOfWeek = WeekFields.of( this.locale ).getFirstDayOfWeek();
List < DayOfWeek > dows =
IntStream
.range( 0 , 7 )
.mapToObj( firstDayOfWeek :: plus )
.collect( Collectors.toList() );
String columnHeaders =
dows
.stream()
.map( dayOfWeek -> dayOfWeek.getDisplayName( TextStyle.SHORT_STANDALONE , this.locale ).substring( 0 , 2 ) )
.collect( Collectors.joining( " " ) );
sb.append( columnHeaders ).append( this.eol );
// Rows (each week)
LocalDate localDate = yearMonth.atDay( 1 ).with( TemporalAdjusters.previousOrSame( firstDayOfWeek ) ); // Get the first date of the month, then move backwards in time to determine the first date that fits our calendar grid. May be the same as the first, or may be earlier date from the previous month.
while ( ! localDate.isAfter( yearMonth.atEndOfMonth() ) ) // "Not after" is a shorter way of saying "is equal to or sooner than".
{
String week =
localDate
.datesUntil( localDate.plusWeeks( 1 ) ) // Get a stream of dates via `LocalDate::datesUntil`. The ending date is exclusive (half-open).
.map( ld -> ( YearMonth.from( ld ).equals( yearMonth ) ? ld.format( CalendarMaker.DAY_FORMATTER ) : " " ) ) // Display the day-of-month number if within the target month, otherwise display a pair of SPACE characters.
.collect( Collectors.joining( " " ) ); // Separate columns with a SPACE in our calendar grid.
sb.append( week ).append( this.eol ); // Add this row of text for the week, and wrap to next line for next loop.
localDate = localDate.plusWeeks( 1 ); // Increment one week at a time to set up our next loop.
}
// Footer (for the month)
sb.append( this.eol ); // Put a blank line after every month.
return sb;
}
// Demonstrate this class with a psvm method.
public static void main ( String[] args )
{
CalendarMaker calendarMaker = new CalendarMaker( "\n" , Locale.CANADA_FRENCH );
// Demonstrate 3 years: previous year, current, and next year.
Year currentYear = Year.now( ZoneId.of( "America/Boise" ) );
List < Year > years = List.of( currentYear.minusYears( 1 ) , currentYear , currentYear.plusYears( 1 ) );
for ( Year year : years )
{
CharSequence calendar = calendarMaker.generateYear( year );
System.out.println( "" );
System.out.println( calendar );
}
}
}运行时。
|------ 2018 ------|
2018 janvier
di lu ma me je ve sa
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 31
2018 février
di lu ma me je ve sa
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
…将区域设置从Locale.CANADA_FRENCH切换到Locale.FRANCE，看看我们如何保留法语，但将文化规范从北美切换到欧洲，以星期一(伦迪)而不是星期日(迪曼什)开始一周。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/56213381
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