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About Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.

Check key existence in TreeMap example

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.

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