Java Collection How to - Retrieve all the keys from HashMap

Question

We would like to know how to retrieve all the keys from HashMap.

Answer

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
/*  w  ww . ja  v a 2 s .  c om*/
public class Main {
  public static void main(String[] args) {
    HashMap<String, Integer> myMap = new HashMap<String, Integer>();

    myMap.put("a",1);
    myMap.put("b",2);
    myMap.put("c",3);
    
    Set<String> stStrKeys = myMap.keySet();
    Iterator<String> itrs = stStrKeys.iterator();
    while (itrs.hasNext()) {
      String s = itrs.next();
      System.out.println(s + ": " + myMap.get(s));
    }
  }
}

The code above generates the following result.