In this example we shall show you how to check a key existence in a TreeMap. The TreeMap API provides methods for this operation. To check a key existence in 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
containsKey(Object key)API method of TreeMap. The method returns true if this map contains a mapping for the specified key and false otherwise,
as described in the code snippet below.
package com.javacodegeeks.snippets.core;
import java.util.TreeMap;
public class CheckKeyTreeMap {
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_2","element_2");
treeMap.put("key_3","element_3");
// boolean containsKey(Object key) returns true if the TreeMap contains mapping for specified key
boolean exists = treeMap.containsKey("key_2");
System.out.println("key_2 exists in TreeMap ? : " + exists);
}
}
Output:
key_2 exists in TreeMap ? : true
This was an example of how to check a key existence in a TreeMap in Java.
