Get lowest and highest key stored in TreeMap

 
import java.util.TreeMap;

public class Main {
  public static void main(String[] args) {
    TreeMap<String, String> treeMap = new TreeMap<String, String>();
    treeMap.put("1", "One");
    treeMap.put("2", "Two");
    treeMap.put("3", "Three");
    treeMap.put("4", "Four");
    treeMap.put("5", "Five");

    System.out.println("Lowest key: " + treeMap.firstKey());
    System.out.println("Highest key: " + treeMap.lastKey());
  }
}