剑指Offer-03替换空格

public static String replaceSpace(String s) {
    //单线程就不用考虑线程安全 当然选择性能更高的StringBuilder
    StringBuilder res = new StringBuilder();
    StringBuilder stringBuffer = new StringBuilder(s);
    for (int i = 0; i < stringBuffer.length(); i++){
        //截取当前位置的字符
        String temp = stringBuffer.substring(i,i+1);
        if (" ".equals(temp)){ //与空格相等则追加%20
            res.append("%20");
        }else { //否则直接追加当前字符
            res.append(temp);
        }
    }
    return res.toString();
}