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.
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.
