如何将字符串末尾的标点符号移动到开头？

Question

我正在尝试编写一个反转字符串顺序的程序，即使是标点符号。但是当我的后面的字符串打印。最后一个单词末尾的标点符号停留在单词的末尾，而不是作为单独的字符处理。

如何将最后一个单词的末尾标点符号分开，以便我可以移动它？

例如： 当我输入：你好我的名字是杰森！

我想：！杰森是我的名字我好你好

反而我得到了：杰森！被命名我喂

import java.util.*; 

class Ideone 
{ 
     public static void main(String[] args) { 

     Scanner userInput = new Scanner(System.in); 

     System.out.print("Enter a sentence: "); 

     String input = userInput.nextLine(); 

     String[] sentence= input.split(" "); 

     String backwards = ""; 

     for (int i = sentence.length - 1; i >= 0; i--) { 
      backwards += sentence[i] + " "; 
     } 

     System.out.print(input + "\n"); 
     System.out.print(backwards); 
     } 
} 

Answer 1

您需要按照下面的步骤：

（1）检查为!字符输入

（2）如果输入包含!然后将其前缀空输出字符串变量

（3）如果输入不包含!然后创建空输出字符串变量

（4）拆分输入字符串，并以相反的顺序重复（你已经这样做了）

您可以参考下面的代码：

public static void main(String[] args) { 
    Scanner userInput = new Scanner(System.in); 
    System.out.print("Enter a sentence: "); 
    String originalInput = userInput.nextLine(); 
    String backwards = ""; 
    String input = originalInput; 

     //Define your punctuation chars into an array 
     char[] punctuationChars = {'!', '?' , '.'}; 
     String backwards = ""; 

      //Remove ! from the input 
     for(int i=0;i<punctuationChars.length;i++) { 
      if(input.charAt(input.length()-1) == punctuationChars[i]) { 
       input = input.substring(0, input.length()-1); 
       backwards = punctuationChars[i]+""; 
       break; 
      } 
     } 

     String[] sentence= input.split(" "); 


     for (int i = sentence.length - 1; i >= 0; i--) { 
      backwards += sentence[i] + " "; 
     } 

     System.out.print(originalInput + "\n"); 

     System.out.print(input + "\n"); 
     System.out.print(backwards); 
    } 

Answer 2

手动清理字符串往往在任何时间变得复杂。这通常是更好的（如果可能）代码什么你想要做的，而不是如何你想做的。

String input = "Hello my name is jason! Nice to meet you. What's your name?"; 

// this is *what* you want to do, part 1: 
// split the input at each ' ', '.', '?' and '!', keep delimiter tokens 
StringTokenizer st = new StringTokenizer(input, " .?!", true); 
StringBuilder sb = new StringBuilder(); 
while(st.hasMoreTokens()) { 
    String token = st.nextToken(); 
    // *what* you want to do, part 2: 
    // add each token to the start of the string 
    sb.insert(0, token); 
} 

String backwards = sb.toString(); 

System.out.print(input + "\n"); 
System.out.print(backwards); 

输出：

Hello my name is jason! Nice to meet you. What's your name? 
?name your What's .you meet to Nice !jason is name my Hello 

这将是一个更容易理解的是一段代码，或者你的未来的自己的工作旁边的人。

这假设你想要移动每个标点符号。如果你只想要一个输入字符串的结尾，你必须切掉它的输入，执行重新排序，并最终将其放置在字符串的开头：

String punctuation = ""; 
String input = "Hello my name is jason! Nice to meet you. What's your name?"; 
System.out.print(input + "\n"); 
if(input.substring(input.length() -1).matches("[.!?]")) { 
    punctuation = input.substring(input.length() -1); 
    input = input.substring(0, input.length() -1); 
} 

StringTokenizer st = new StringTokenizer(input, " ", true); 
StringBuilder sb = new StringBuilder(); 
while(st.hasMoreTokens()) { 
    sb.insert(0, st.nextToken()); 
} 
sb.insert(0, punctuation); 
System.out.print(sb); 

输出：

Hello my name is jason! Nice to meet you. What's your name? 
?name your What's you. meet to Nice jason! is name my Hello 

Answer 3

与其他答案一样，首先需要将标点符号分开，然后重新排序，最后将标点符号放在开头。

你可以利用String.join（）和Collections.reverse（），String.endsWith（）来获得更简单的答案...

String input = "Hello my name is jason!"; 
String punctuation = ""; 
if (input.endsWith("?") || input.endsWith("!")) { 
    punctuation = input.substring(input.length() - 1, input.length()); 
    input = input.substring(0, input.length() - 1); 
} 
List<String> words = Arrays.asList(input.split(" ")); 
Collections.reverse(words); 
String reordered = punctuation + String.join(" ", words); 
System.out.println(reordered); 

Answer 4

下面的代码应该为你工作

import java.util.regex.Matcher; 
import java.util.regex.Pattern; 
public class ReplaceSample { 
    public static void main(String[] args) { 
     String originalString = "TestStr?"; 
     String updatedString = ""; 
     String regex = "end\\p{Punct}+|\\p{Punct}+$"; 
     Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE); 
     Matcher matcher = pattern.matcher(originalString); 
    while (matcher.find()) { 
      int start = matcher.start(); 
      updatedString = matcher.group() + originalString.substring(0, start);<br> 
     } 
     System.out.println("Original -->" + originalString + "\nReplaced -->" +  updatedString); 
    } 
} 

Answer 5

不要用空格分开;按字词划分。那么你不需要关心标点符号甚至把空格放回去，因为你也只是将它们反转过来！

而且它只有1行：

Arrays.stream(input.split("\\b")) 
    .reduce((a, b) -> b + a) 
    .ifPresent(System.out::println); 

见live demo。