将 concat 与 int 一起使用？

Question

我正在尝试执行以下操作：

如果用户输入了 1 到 100 之间的数字，则：

打印出从 1 到给定数字的每个序数。

以下示例适用于输入值 25：

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

12th

13th

14th

15th

16th

17th

18th

19th

20th

21st

22nd

23rd

24th

25th

我不知道如何在st, nd, rd, th不使用concat.

这是我的代码：

import java.util.Scanner;

public class Main {

  public static void main(String[] args) {

    Scanner scnr = new Scanner(System.in);

   int userNum;

  userNum = scnr.nextInt();

  for (int i=1; i<=userNum; i++) {

  System.out.println(i);

    }

  }

}

有没有其他方法可以做到这一点？谢谢。

Answer 1

Java 中的特殊String连接运算符 (&nbsp;+) 会自动将标量转换为字符串（当字符串在左侧时）。你可以这样做：System.out.println(""+i+getPostfix(i));wheregetPostfix将为给定的整数（-st、-nd 等）返回一个合适的后缀。我将此功能的实现留作练习。

Answer 2

你可以用 printf 做到这一点for (int i=1; i<=userNum; i++) {&nbsp; &nbsp; &nbsp;System.out.printf("%d%s\n",i,i%10==1 && i>19 ? "st " : i%10==2 && i>19 ? "nd " : i%10==3 && i>19 ? "rd " : "th ");}

Answer 3

你可以不使用 concat 来做到这一点。您可以使用模数检查 number -st -nd -rd (% 10)import java.util.*;import java.util.AbstractMap.SimpleEntry;import java.util.stream.Collectors;import java.util.stream.IntStream;import java.util.stream.Stream;public class Main {private static final String DEFAULT_POSTFIX = "th";private static final Map<Integer, String> POSTFIX_MAP =&nbsp; &nbsp; &nbsp; &nbsp; Stream.of(&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new SimpleEntry<>(1, "st"),&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new SimpleEntry<>(2, "rd"),&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new SimpleEntry<>(3, "nt"))&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));private static String getPostfix(int number) {&nbsp; &nbsp; if (Arrays.asList(11,12,13).contains(number)) return DEFAULT_POSTFIX;&nbsp; &nbsp; return Optional&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .ofNullable(POSTFIX_MAP.get(number % 10))&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .orElse(DEFAULT_POSTFIX);}public static void main(String[] args) {&nbsp; &nbsp; Scanner scanner = new Scanner(System.in);&nbsp; &nbsp; int userNum = scanner.nextInt();&nbsp; &nbsp; IntStream&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .rangeClosed(1, userNum)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .forEach(it -> System.out.println(it + getPostfix(it)));}}