Why is this hashmap iterating through an infinite loop?

[Patrick Noah]

I am writing a method to determine whether two strings are anagrams of one another. I am trying to print out the contents of my hashmap to debug it but am encountering an infinite loop. Can someone please tell me why this is happening? Thank you.

public boolean isAnagram(String str, String str2)
    {
        if(str == null || str2 == null)
            return false;
        if(str.length() != str2.length())
            return false;
        HashMap<String, Integer> h = new HashMap<String, Integer>();
        // set hashmap values to 0 so they can be incremented
        for(int index = 0; index < str.length(); index++)
        {
            String currentChar = new String("" + str.charAt(index));
            h.put(currentChar, 0);
        }
        // create a hash of str that has how many times each char in the str occurs as the value
        for(int x = 0; x < str.length(); x++)
        {
            String currChar = new String("" + str.charAt(x));
            h.put(currChar, h.get(currChar).intValue()+1);
        }
        // see if the str contain the same letters, decrement the count for each matching char
        for(int i=0; i < str2.length(); i++)
        {
            String curr_char = new String("" + str2.charAt(i));
            if(h.containsKey(curr_char))
            {
                h.put(curr_char, h.get(curr_char).intValue()-1);
            }
            else
                return false;
        }
        // print out the hash
        while(h.keySet().iterator().hasNext())
        {
            String thechar = h.keySet().iterator().next();
            System.out.println(thechar);
            System.out.println(h.get(thechar));
           /* if(!h.values().iterator().next().equals(0))
                return false;*/
        }
                  
        return true;    
    }

[Alexander Sales]

Is this part reliable?

// print out the hash 
while(h.keySet().iterator().hasNext()) 
{ 
String thechar = h.keySet().iterator().next(); 
 

[Matthew Brown]

Every time you call iterator() you get a new one, so you reset the position. So you need to keep calling next() on the same Iterator.