The java.util.TreeMap.lastKey() is used to retrieve the last or the highest key present in the map.
Syntax:
tree_map.lastKey()
Parameters: The method does not take any parameters.
Return Value: The method returns the last key present in the map.
Exception: The method throws NoSuchElementException if the map is empty.
Below programs illustrate the working of java.util.TreeMap.lastKey() method:
Program 1:
// Java code to illustrate the lastKey() methodimport java.util.*;  public class Tree_Map_Demo {    public static void main(String[] args)    {          // Creating an empty TreeMap        TreeMap<Integer, String> tree_map = new TreeMap<Integer, String>();          // Mapping string values to int keys        tree_map.put(10, "Geeks");        tree_map.put(15, "4");        tree_map.put(20, "Geeks");        tree_map.put(25, "Welcomes");        tree_map.put(30, "You");          // Displaying the TreeMap        System.out.println("The Mappings are: " + tree_map);          // Displaying the lastKey of the map        System.out.println("The last key is " + tree_map.lastKey());    }} |
Output:
The Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The last key is 30
Program 2:
// Java code to illustrate the lastKey() methodimport java.util.*;  public class Tree_Map_Demo {    public static void main(String[] args)    {          // Creating an empty TreeMap        TreeMap<String, Integer> tree_map = new TreeMap<String, Integer>();          // Mapping int values to string keys        tree_map.put("Geeks", 10);        tree_map.put("4", 15);        tree_map.put("Geeks", 20);        tree_map.put("Welcomes", 25);        tree_map.put("You", 30);          // Displaying the TreeMap        System.out.println("The Mappings are: " + tree_map);          // Displaying the lastKey of the map        System.out.println("The last key is " + tree_map.lastKey());    }} |
Output:
The Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
The last key is You
