如何反转Java字符串的单词 [英] How to reverse words of a Java String

问题描述

我正在尝试制作一个程序以从扫描仪获取字符串的输入，但是我想分解输入的字符串并颠倒单词的顺序.这是我到目前为止所拥有的.

Im trying to make a program to take input for a string from the scanner, but i want to break up the string that was inputed and reverse the order of words. This is what i have so far.

Scanner input = new Scanner(System.in);
System.out.println("Enter your string");
StringBuilder welcome = new StringBuilder(input.next());
int i;
for( i = 0; i < welcome.length(); i++ ){
    // Will recognize a space in words
    if(Character.isWhitespace(welcome.charAt(i))) {
        Character a = welcome.charAt(i);
    }   
}

我要做的是在它识别出空格之后，捕获每个空格之前的所有内容，依此类推，然后重新排列字符串.

What I want to do is after it recognizes the space, capture everything before it and so on for every space, then rearrange the string.

推荐答案

我确实建议先反转整个字符串. 然后反转两个空格之间的子字符串.

I did suggest first reverse the whole string. Then reverse the substring between two spaces.

public class ReverseByWord {

    public static String reversePart (String in){
        // Reverses the complete string
        String reversed = "";
        for (int i=0; i<in.length(); i++){
            reversed=in.charAt(i)+reversed;
        }
        return reversed;
    }

    public static String reverseByWord (String in){
        // First reverses the complete string
        // "I am going there" becomes "ereht gniog ma I"
        // After that we just need to reverse each word.
        String reversed = reversePart(in);
        String word_reversal="";
        int last_space=-1;
        int j=0;
        while (j<in.length()){
            if (reversed.charAt(j)==' '){
                word_reversal=word_reversal+reversePart(reversed.substring(last_space+1, j));
                word_reversal=word_reversal+" ";
                last_space=j;
            }
            j++;
        }
        word_reversal=word_reversal+reversePart(reversed.substring(last_space+1, in.length()));
        return word_reversal;
    }

    public static void main(String[] args) {
        // TODO code application logic here
        System.out.println(reverseByWord("I am going there"));
    }
}

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