In this example we shall show you how to obtain the lowest and highest keys from a TreeMap. The TreeMap API provides methods for these operations. To obtain the lowest and highest keys from a TreeMap one should perform the following steps:
- Create a new TreeMap.
- Populate the map with elements, with
put(K key, V value)API method of TreeMap. - Invoke
firstKey()API method of TreeMap. The method returns the first (lowest) key currently in this map. - Invoke
lastKey()API method of TreeMap. The method returns the last (highest) key currently in this map,
as described in the code snippet below.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | package com.javacodegeeks.snippets.core; import java.util.TreeMap; public class LowHighKeyTreeMap { public static void main(String[] args) { // Create a TreeMap and populate it with elements TreeMap treeMap = new TreeMap(); treeMap.put("key_1","element_1"); treeMap.put("key_3","element_3"); treeMap.put("key_2","element_2"); treeMap.put("key_4","element_4"); treeMap.put("key_5","element_5"); // Object firstKey() returns the lowest key in the TreeMap System.out.println("Lowest key in TreeMap is : " + treeMap.firstKey()); // Object lastKey() returns the highest key in the TreeMap System.out.println("Highest key in TreeMap is : " + treeMap.lastKey()); }} |
Output:
Lowest key in TreeMap is : key_1
Highest key in TreeMap is : key_5
This was an example of how to obtain the lowest and highest keys from a TreeMap in Java.
