替换空格

 1 public class Solution {
 2     public String replaceSpace(StringBuffer str) {
 3         int n = str.length();
 4         int sum = 0;
 5         for (int i = 0; i < n; ++i) {
 6             if (str.charAt(i) == ‘ ‘) sum++;
 7         }
 8         System.out.println(n);
 9         str.setLength(n + sum * 2);
10         
11         int i = n - 1, j = i + sum * 2;
12         while (i >= 0) {
13             if (str.charAt(i) == ‘ ‘) {
14                 str.setCharAt(j--, ‘0‘);
15                 str.setCharAt(j--, ‘2‘);
16                 str.setCharAt(j--, ‘%‘);
17                 i--;
18                
19             } else {
20                 str.setCharAt(j, str.charAt(i));
21                 j--;i--;
22                 
23             }
24             
25         }
26         return str.toString();
27     }
28 }