What is the HashTable.containsKey() method in Java?

In this shot, we will discuss how to use the HashTable.containsKey() method in Java.

The HashTable.containsKey() method is present in the HashTable class inside the java.util package.

The HashTable.containsKey() method is used to check whether a particular key is present in the HashTable or not.

Syntax

HashTable.containsKey(Key)

Parameter

The HashTable.containsKey() method takes one parameter.

  • Key: The key whose presence needs to be checked in the HashTable.

Return value

This method returns a Boolean value.

  • True: If the key is present in the HashTable.

  • False: If the key is not present in the HashTable.

Code

Let’s look at the code snippet below to understand it better.

import java.util.*;
class Main
{
public static void main(String[] args) 
{
Hashtable<Integer, String> h1 = new Hashtable<Integer, String>();
h1.put(1, "Let's");
h1.put(5, "see");
h1.put(2, "Hashtable.contains()");
h1.put(27, "method");
h1.put(9, "in java.");
System.out.println("The key=5 is present in Hashtable?: "+h1.containsKey(5));
System.out.println("The key=9 is present in Hashtable?: "+h1.containsKey(9));
System.out.println("The key=14 is present in Hashtable?: "+h1.containsKey(14));
System.out.println();
}
}

Explanation

  • In line 1, we imported the required package.

  • In line 2, we made a Main class.

  • In line 4, we made a main function.

  • In line 6, we declared a Hashtable consisting of Integer type keys and String type values.

  • In lines 8 to 12, we inserted values in the Hashtable by using the Hashtable.put() method.

  • In lines 14 to 16, we display whether the key passed as argument is present in the HashTable or not with a message.

In this way, we can use HashTable.containsKey() to check whether the particular key is present in the HashTable or not.

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