TreeMap lastKey() method in java

by September 17, 2020 Java

Let’s learn TreeMap lastKey() method in java.

TreeMap lastKey() method in java

lastKey() method of TreeMap class returns the last (highest) key currently in this map.

Syntax:

public K lastKey()

Parameters:

lastKey() method do not take any parameters.

Throws:

NoSuchElementException – if this map is empty.

Now let’s see example on TreeMap lastKey() method.

import java.util.TreeMap;
public class TreeMapLastKeyMethodExample
{
   public static void main(String[] args)
   {
      TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
      tm.put(99, "yellow");
      tm.put(86, "violet");
      tm.put(93, "red");
      tm.put(36, "green");
      tm.put(29, "blue");
      System.out.println("Given TreeMap is: " + tm);
      // display lastKey of TreeMap
      System.out.println("last key is: " + tm.lastKey());
   }
}

Output:

Given TreeMap is: {29=blue, 36=green, 86=violet, 93=red, 99=yellow}
last key is: 99

Let’s map integer values to string keys.

import java.util.TreeMap;
public class TreeMapLastKeyMethodExample
{
   public static void main(String[] args)
   {
      TreeMap<String, Integer> tm = new TreeMap<String, Integer>();
      tm.put("yellow", 99);
      tm.put("violet", 86);
      tm.put("red", 93);
      tm.put("green", 36);
      tm.put("blue", 29);
      System.out.println("Given TreeMap is: " + tm);
      // display lastKey of TreeMap
      System.out.println("last key is: " + tm.lastKey());
   }
}

Output:

Given TreeMap is: {blue=29, green=36, red=93, violet=86, yellow=99}
last key is: yellow

Also read – nested classes in java