剑指Offer-4

题目：

请实现一个函数，把字符串中的每个空格替换成”%20”，例如”We are happy.”，则输出”We%20are%20happy.”

实现

// coding = javaimport java.util.ArrayList;import java.util.List;public class Solution4 {    public static void replaceString(String input){        if(input.length()<1){            return;        }        List str_list = new ArrayList<Character>();        for(int i =0;i<input.length();i++){            char ch = input.charAt(i);            if(ch ==' '){                str_list.add('%');                str_list.add('2');                str_list.add('0');            }            else{                str_list.add(ch);            }        }        String result ="";        for(int i =0;i<str_list.size();i++) {            result += str_list.get(i);        }        System.out.print(result);    }    public static void main(String[] args){        String input = "We are happy.";        Solution4.replaceString(input);    }}