Reverse Sentence

ReverseSentence.java

import java.lang.Math;
import java.util.*;

// our main class becomes a file but the main method is still found
public class HelloWorld
{
  public static void main(String[] args)
  {
    ReverseSentence myObject = new ReverseSentence();
    String reversed = myObject.reverseString("Hello,, . , I would, like to reverse. .      this. sentence, and another thing.  Thank   You.");
    System.out.println(reversed);
  }
}

// this will become its own file too (and these can be in any order)
public class ReverseSentence
{
  
  public String reverseString(String sentence)
  {
    StringBuffer output = new StringBuffer();
    HashMap<Integer, Character> punctMap = new HashMap<Integer, Character>();
    
    for (int i=0; i<sentence.length(); i++){ 
      if (sentence.charAt(i) == ',' || sentence.charAt(i) == '.' || sentence.charAt(i) == ' '){
        punctMap.put(sentence.length() - i - 1, sentence.charAt(i));
        System.out.println(sentence.length() - i - 1 + " char: " + sentence.charAt(i));
      }
      
    }
    
    String[] arrWords = sentence.split("([ ,.]+)");
    
    for (int j=arrWords.length - 1; j >= 0; j--){
      while (punctMap.get(output.length()) != null){
      	output.append(punctMap.get(output.length()));
      }
       
      output.append(arrWords[j]);
      
      System.out.println(arrWords[j]);
      
    }                  
    
    return output.toString();
  }
}

/*Output:

87 char: ,
86 char: ,
85 char:  
84 char: .
83 char:  
82 char: ,
81 char:  
79 char:  
73 char: ,
72 char:  
67 char:  
64 char:  
56 char: .
55 char:  
54 char: .
53 char:  
52 char:  
51 char:  
50 char:  
49 char:  
48 char:  
43 char: .
42 char:  
33 char: ,
32 char:  
28 char:  
20 char:  
14 char: .
13 char:  
12 char:  
6 char:  
5 char:  
4 char:  
0 char: .
You
Thank
thing
another
and
sentence
this
reverse
to
like
would
I
Hello
.You   Thank  .thing another and ,sentence .this      . .reverse to like ,would I , . ,,Hello

*/