题解 | #翻转单词序列#

遍历的时候将字符串从前到后加入到StringBuilder中，然后注意空格输出就行。

    public String ReverseSentence(String str) {
        if (str == null ||str.length()==0) {
            return "";
        }
        String[] strings = str.split(" ");
        StringBuilder sb = new StringBuilder();
        int len = strings.length;
        for (int i = 0; i < len; i++) {
            if (i == len-1) {
                sb.append(strings[len-1-i]);
            }else {
                sb.append(strings[len-1-i]+" ");
            }
        }
        return sb.toString();
    }
}