How to sort Map values by key in Java?

I have a Map that has strings for both keys and values.

Data is like following:

“question1”, “1”
“question9”, “1”
“question2”, “4”
“question5”, “2”

I want to sort the map based on its keys. So, in the end, I will have question1, question2, question3….and so on.

Eventually, I am trying to get two strings out of this Map.

• First String: Questions ( in order 1 ..10)
• Second String: Answers (in the same order as the question)

Right now I have the following:

Iterator it = paramMap.entrySet().iterator();
while (it.hasNext()) {
    Map.Entry pairs = (Map.Entry) it.next();
    questionAnswers += pairs.getKey() + ",";
}

This gets me the questions in a string but they are not in order.