java String类replace方法源码分析

    public String replace(char oldChar, char newChar) {
        if (oldChar != newChar) 
        {
            int len = value.length;//value就是一个数组,这里得到string字符串的长度
            int i = -1;
            char[] val = value; /* avoid getfield opcode */

            while (++i < len)      //先确保字符串中有旧的字符
            {
                if (val[i] == oldChar) 
                {break;}
            }

            if (i < len) 
            {
                char buf[] = new char[len];
                for (int j = 0; j < i; j++) 
                {
                    buf[j] = val[j];
                }
                while (i < len) {
                    char c = val[i];
                    buf[i] = (c == oldChar) ? newChar : c;
                    i++;
                }
                return new String(buf, true);
            }
        }
        return this;
    }    public String replace(char oldChar, char newC