实现字符串反转

今天来看看如何实现字符串反转，比如输入Game is Over,输出Over is Game

public class Question {
    public static void main(String[] args) {
        String str = "Game is over adfd aaaa cccc";
        System.out.println("============="+reverseStr(str));
    }

    private static String reverseStr(String str) {
        //当前字符串
        String temp = str;
        StringBuilder sb = new StringBuilder();
        //每个空格的位置，从后向前查找
        int index = temp.lastIndexOf(" ");
        //循环查找空格是否存在
        while (index != -1) {
            //每个空格之后的字符串
            String subStr = temp.substring(index, temp.length());
            sb.append(subStr);
            //空格之前的字符串
            String lastStr = temp.substring(0,index);
            //剩下字符串中空格的位置
            index = lastStr.lastIndexOf(" ");
            //没有空格，说明到了最后一个单词，进行添加并且需要手动添加一个空格和前面的单词隔开
            if (index == -1) {
                sb.append(" ").append(lastStr);
            }
            temp = lastStr;
        }
        //除去第一个空格
        sb.replace(0,1,"");
        return sb.toString();
    }
}