Java – get the maximum key from HashMap?

I have a HashMap defined like this

HashMap<String,Integer> uniqueNames = new HashMap<String,Integer>();

It stores a name and the occurrence of that name For example

uniqueNames.put("lastname",42);

How to get the highest name?

For more information, I'm using the "people" binary search tree to store unique names and frequencies in HashMap What I want to do is print the most commonly used last names. Someone told me to use HashMap because I want to store a string and an integer Maybe I should use a class to store names and frequencies? Someone can make some suggestions

Solution

If you have to use a HashMap, the easiest way may be to cycle through the map to find the maximum value

Entry<String,Integer> maxEntry = null;

for(Entry<String,Integer> entry : uniqueNames.entrySet()) {
    if (maxEntry == null || entry.getValue() > maxEntry.getValue()) {
        maxEntry = entry;
    }
}
// maxEntry should Now contain the maximum,