Reversing a String Without Reverse Function or loops

So I have to reverse a string but like an example would be reverse Hello World. Well my code reverses it like this dlroW olleH and you have to reverse it like World Hello. This is my code below can someone help me fix it or tell me what im doing wrong please. I need to do as you create a new object and input the data through the object and then call the method.

public class reverseMe {
  public String reverseMe(String s) {
         if(s.length() == 0)
            return "";
            return s.charAt(s.length() - 1) + reverseMe(s.substring(0,s.length()-1));
 }
}

What do you mean for "without reverse function or loops". First of all in java are called methods, not functions, and second in some way you need to iterate the strings. This code just does the job with a recursive method. Call it from your constructor and you’re done. There aren't any already built-in java methods to do what you want.

public class HelloWorld{


public String recursiveReverse(String[] words,StringBuilder b,int length){
     if (length < 0) 
        return b.toString();
     else{
        b.append(words[length] + " ");
        length--;
        return recursiveReverse(words,b,length);
     }
            
}

public String reverse (String input){
   String[] words = input.split(" ");
   StringBuilder reverse = new StringBuilder();
   return recursiveReverse(words,reverse,words.length-1);
}

     public static void main(String []args){
        HelloWorld a = new HelloWorld();
        System.out.println(a.reverse("hello this is a test reverse this string"));
     }
}

Output:

string this reverse test a is this hello

This answer assumes the following:

• Can't use built-in reverse() function, such as found on StringBuilder and Collections.

• Can't use loops.

• Input can contain any number of words.

• Words are separated by a single space.

First, the easiest solution would be to split() the input and then use Stream logic to combine the words in reverse order, however I consider Stream logic to be "Loop logic", so that won't do.

That leaves the use of a recursive method as a solution, similar to the attempt in the question:

static String reverseWords(String input) {
	int idx = input.indexOf(' ');
	if (idx == -1)
		return input;
	return reverseWords(input.substring(idx + 1)) + ' ' + input.substring(0, idx);
}

Test

System.out.println(reverseWords("Hello World"));
System.out.println(reverseWords("The quick brown fox jumps over the lazy dog"));

Output

World Hello
dog lazy the over jumps fox brown quick The

Since you can't use any loops or reverse methods, that would leave a recursive method.
However, this is not very efficient.

It works by repeatedly splitting on string less the last word of the previous string and then returning a new String in reversed order.

ReverseMe r = new ReverseMe();                                                    
String reversed =r.reverseMe("This is a test of reversing a string");             
System.out.println(reversed);                                                     
                                                                                   
                                                                                      
public String reverseMe(String s) {
	String arr[] = s.split("\\s+");
	if (arr.length > 1) {
		return arr[arr.length-1] + " " + reverseMe(s.substring(0, s.lastIndexOf(" ")));			  
	} 
	return arr[arr.length-1];
	
}

Prints

string a reversing of test a is This
                                                                                     

</details>