TreeMap lastKey() method in 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.

Also read – TreeMap in java

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