Reverse sentence

class Main {
    private static void reverseWord(char c[], int a, int b) {
        for(int i=0; i<=(b-a)/2; i++) {
            char ch = c[a+i];
            c[a+i] = c[b-i];
            c[b-i] = ch;
        }
    }
    public static String reverseString(String str) {
        char s[] = str.toCharArray();
        reverseWord(s,0,s.length-1);
        int j = 0;
        for(int i=0; i<s.length; i++) {
            if(s[i] == ' ') {
                reverseWord(s,j, i-1);
                j = i+1; 
            }
        }
        reverseWord(s, j, s.length-1);
        
        return new String(s);
    }
    public static void main(String[] args) {
        String str = "this is santhosh";
        System.out.println(reverseString(str));
    }
}