firstEntry(): It returns the key-value pair having the least key (Key having lowest value). It returns the pair that associated with least key. It returns null if TreeMap is empty.
import java.util.TreeMap;
class ExampleOfTreeMap
{
public static void main(String arg[])
{
TreeMap<Integer, String> listOfNames = new TreeMap<Integer, String>();
listOfNames.put(3, "C");
listOfNames.put(1, "A");
listOfNames.put(2, "D");
listOfNames.put(6, "B");
listOfNames.put(8, "B");
// It return the Pair of Key and value of least Key of TreeMap
System.out.println("Pair of least Key :"+listOfNames.firstEntry());
}
}
Output: Pair of least Key :1=A
