用Java实现I am a student逆序输出为student a am I，不借助split方法和StringBuffer！

用Java实现I am a student逆序输出为student a am I,不使用split方法和StringBuffer，只用最原始的数组
总体思路：先整体后局部

public class ReverseString {

	public  static void swap(char[] ch,int a,int b) {
        char tmp;
        for(;a < b;a++,b--) {
            tmp = ch[a];
            ch[a] = ch[b];
            ch[b] = tmp;
        }
    }

	 public static String reverseStr(String str) {
	        char[] chars = str.toCharArray();
	        //先逆序整个数组tneduts a ma I
	        swap(chars,0,chars.length-1);
	        //再以空格为界逆序每个单词
	        int start = 0;
	        for(int i = 1;i < chars.length;i++) {
	            if(chars[i] == ' ') {
	                swap(chars,start,i-1);
	                start = i+1;
	            }
	        }
	        return String.valueOf(chars);
	    }

	public static void main(String[] args) {
		String str = "I am a student";
		System.out.println(reverseStr(str));;
	}

}