替换空格

 public String replaceBackend(String word){
    String a = word.toString();
    String b = a.replaceAll(" ","%20");
    return b;
    }

       public String replaceBackend(String word){
            String a = word.toString();
            char[] b = a.toCharArray();
            StringBuffer c = new StringBuffer();
            for(int i = 0 ;i<b.length;i++){
                if(b[i] == ' '){
                    c.append("%20");
                }else{
                    c.append(b[i]);
                }
            }
                return c.toString();
                
            }
       public static void main(String args[]){
           String word = "we are happy";
           aaa a = new aaa();
           System.out.println(a.replaceBackend(word));
       }