Check if a particular key exists in Java TreeMap example

This Java Example shows how to check if TreeMap object contains a particular key using containsKey method of TreeMap class.

import java.util.TreeMap;

public class CheckParticularKeyExistTreeMapExample {

 public static void main(String[] args) {

  // create object of TreeMap

  TreeMap phoneBook = new TreeMap();

  // Adding key value pairs to TreeMap

  phoneBook.put("John", "245745");
  phoneBook.put("Joy", "245786");
  phoneBook.put("Roy", "233783");

  /**
   * To check whether a particular key exists in
   * TreeMap use boolean containsKey(Object key) method
   * of TreeMap class. It returns true if the TreeMap
   * contains mapping for specified key otherwise false.
   **/

  boolean blnExists = phoneBook.containsKey("Joy");
  System.out.println("Name 'Joy' exists in TreeMap ? : " + blnExists);

 }
}

The output is:


Name 'Joy' exists in TreeMap ? : true