Reverse words in a string (Java note some detail handling)

title:Reverse Words in a string

Given an input string, reverse the string word by word.

For example,
Given s = " the sky is blue ",
Return " blue is sky the ".

parsing: outputting words in a string in reverse order

With the help of a stack, the string was traversed backwards, encountered empty, skipped until non-empty characters, stitched word, and so on again encountered empty, get a word, add a stack,

And so on until the last character of S is traversed.

Finally, the word in the stack is output in turn

Java Encoding:

Method One:

Public String reversewords (string s) {if (s = = NULL | | s.length () = = 0) return s; int index = 0; //The pointer to traverse        int len = S.length (); stack<string> stack = new stack<string> (); Stack, advanced out, sequential save word, reverse output StringBuilder Sbuilder = new StringBuilder ();        Record each word char[] characters = S.tochararray ();            while (Index < len) {//traversal string for (; index < len && Characters[index] = = "; ++index);//Skip NULL characters for (; index < len && Characters[index]! = "; ++index) {//Stitching word sbuilder.append (characters[            Index]);                } if (Sbuilder.length () > 0) {//to press a valid word into the stack Stack.push (sbuilder.tostring ()); Sbuilder.delete (0,sbuilder.length ());//Empty StringBuilder}} sbuilder.delete (0,sbuilder.len Gth ());//Empty StringBuilder while (Stack.size () > 1) {//Not last word, output, plus space Sbuilder.append (stack.pop        () + " ");          if (stack.size () = = 1)//The last word, output, no spaces, here to determine whether the stack is empty, because the possible input string is empty sbuilder.append (Stack.pop ());      return sbuilder.tostring (); }

Method Two:

The regular expression, \s, represents a space, + represents at least one space, so that multiple spaces separated by Word can be extracted.

Public String reversewords (string s) {        string[] words = S.split ("\\s+");   Regular expression        StringBuffer sb = new StringBuffer ();                for (int i = words.length-1; I >= 0; i.) {            sb.append (Words[i] + "");        }                Return sb.tostring (). Trim ();    }

Reverse words in a string (Java note some detail handling)