用java写一个英文句子反转的方法

[jason_kou]

用java写一个英文句子反转的方法：

/**
 * 要求：将一个英文句子反转， e.g. much. very you love I => I love you very much.
 * 但不能使用String的库函数：split,indexOf,lastIndexOf,subString
 * 
 */

[jason_kou]

自己顶一下，嘎嘎，基础题。。

[bootupnow]

那就用StringBuffer的reverse()，很好很强大！

[jason_kou]

如果用这个就太简单了，没有其他简单方法么？

[haoxiongok]

关注哈

[jason_kou]

public class ReversalWords {
	/**
	 * 
	 * @author 流浪的鱼
	 * @version 1.0
	 * 
	 */
	public static String doReversal(String str) {
		char[] c = str.toCharArray();
		String result = "";
		StringBuffer sb = new StringBuffer();
		for (int i = c.length - 1; i >= 0; i--) {
			if (c[i] != ' ') {
				sb.append(c[i]);
			}
			if (c[i] == ' ' || i == 0) {
				result = result + sb.reverse().toString();
				if (i != 0)
					result += " ";
				sb.delete(0, sb.length());
			}
		}
		return result;
	}

	public static void main(String[] args) {
		System.out.println(doReversal("much. very you love I"));
	}
}

这个感觉有点投机，，谁还有比较巧的办法？

[云上飞翔]

[Quote=引用 2 楼 bootupnow 的回复:]
那就用StringBuffer的reverse()，很好很强大！
[/Quote]
答：不，不是的．用StringBuffer的reverse()得到的结果是不正确的，不是楼主要的那个．

[kingofvc]

StringTokenizer 来读取以空格为分隔的String
定义一个String 比如result
while(tokenizer.hasMoreToken()){
result=tokenizer.nextToken()+" "+result;
}

[云上飞翔]

答：英文句子反转，单词间的空格数要保持原样才行啊！
代码很简单：

public static String reverse(String s)//句子反转单词之间是空格,保持单词间空格原样
	{
		int pos=0;
		StringBuilder sb=new StringBuilder();
		for(int i=0;i<s.length();i++)
		{
			char c=s.charAt(i);
			if(c==' ')
			{
					pos=0;
			}
			sb.insert(pos, c);
			if(c!=' '){pos++;}
		}
		return sb.toString();
	}

若：String s="much. very you love I";
System.out.println(reverse(s));
结果是：
I love you very much.

[anqini]

[Quote=引用 8 楼 jiangnaisong 的回复:]
答：英文句子反转，单词间的空格数要保持原样才行啊！
代码很简单：

Java code
public static String reverse(String s)//句子反转单词之间是空格,保持单词间空格原样
{
int pos=0;
StringBuilder sb=new StringBuilder();
for(int i=0;i<s.length();i++)
{
char c=s.charAt(i);
if(c==' ')
{
pos=0;
…
[/Quote]

8错8错!江奶松~

[youzi530]

public class StringBuffer1{
public static void main(String[]args){
StringBuffer sb=new StringBuffer("I love you very much.");
StringBuffer str=sb.reverse();
System.out.println(str);
}
}
楼主我刚才写了这种简单的方法,不知是不是呢?

[zenny_chen]

献丑了：

import static java.lang.System.out;


class StringReverse {
	
	public static boolean isBlank(char c) {
		return (c == ' ' || c == '\t' || c == '\r' || c == '\n');
	}
	
	public static String sentenceReverse(String src) {
		
		if(src == null)
			return null;
		
		char[] contents = src.toCharArray();
		final int length = contents.length;
		
		if(length < 2)
			return src;
		
		char[] res = new char[length];
		int startPos = -1, endPos = -1, destCursor=0;
		boolean blankState = true;
		
		for(int srcCursor=length-1; srcCursor>=0; srcCursor--) {
			if(isBlank(contents[srcCursor])) {
				if(!blankState) {
					for(int i=endPos; i<=startPos; i++)
						res[destCursor++] = contents[i];
					endPos = -1;
					blankState = true;
				}
				res[destCursor++] = contents[srcCursor];
			}
			else {
				if(blankState) {
					blankState = false;
					endPos = startPos = srcCursor;
				}
				else
					endPos--;
			}
		}
		if(endPos >= 0) {
			for(int i=endPos; i<=startPos; i++)
				res[destCursor++] = contents[i];
		}
		
		return String.valueOf(res);
	}
}


public class Test
{
	public static void main(String[] args) {
		
		out.println(StringReverse.sentenceReverse("much.  very you love I"));
	}
}

[jason_kou]

8楼答案最为简单，赞一个

[zenny_chen]

不好意思，上面有个逻辑上的瑕疵，这里改正一下：

import static java.lang.System.out;


class StringReverse {
	
	public static boolean isBlank(char c) {
		return (c == ' ' || c == '\t' || c == '\r' || c == '\n');
	}
	
	public static String sentenceReverse(String src) {
		
		if(src == null)
			return null;
		
		char[] contents = src.toCharArray();
		final int length = contents.length;
		
		if(length < 2)
			return src;
		
		char[] res = new char[length];
		int startPos = -1, endPos = -1, destCursor=0;
		boolean blankState = true;
		
		for(int srcCursor=length-1; srcCursor>=0; srcCursor--) {
			if(isBlank(contents[srcCursor])) {
				if(!blankState) {
					for(int i=endPos; i<=startPos; i++)
						res[destCursor++] = contents[i];

					blankState = true;
				}
				res[destCursor++] = contents[srcCursor];
			}
			else {
				if(blankState) {
					blankState = false;
					endPos = startPos = srcCursor;
				}
				else
					endPos--;
			}
		}
		if(!blankState) {
			for(int i=endPos; i<=startPos; i++)
				res[destCursor++] = contents[i];
		}
		
		return String.valueOf(res);
	}
}


public class Test
{
	public static void main(String[] args) {
		
		out.println(StringReverse.sentenceReverse("much. very you love I"));
	}
}