Java Hashtable get() Method

The Hashtable.get() method is a built-in method of the java.util.Hashtable class. This method is used to retrieve or fetch the value mapped by a particular key mentioned in the parameter. It returns NULL when the table contains no such mapping for the key. In this article, we will learn about the Hashtable.get() method in Java with its syntax and practical examples.

Syntax of Hashtable get() Method

Hashtable.get(Object key);

• Parameters: The method takes one parameter, "key" of object type and refers to the key whose associated value is supposed to be fetched.
• Return Value: The method returns the value associated with the "key"  in the parameter.

When to Use the get() Method?

We use get() method,

• To retrieve values stored against a key in the hashtable.
• To check if a specific key exists by evaluating if the returned value is null or not.

Examples of Java Hashtable get() Method

Example 1: In this example, we create a hashtable with integer keys and string values. We insert key-value pairs and retrieve values using the get() method.

// Java program to illustrate Hashtable get() method
import java.util.*;

public class Geeks {
    public static void main(String[] args) {
        
        // Create an empty Hashtable
        Hashtable<Integer, String> ht = new Hashtable<>();

        // Insert key-value pairs into the hashtable
        ht.put(10, "Geeks");
        ht.put(15, "4");
        ht.put(20, "Geeks");
        ht.put(25, "Welcomes");
        ht.put(30, "You");

        System.out.println("Initial Table is: " + ht);

        // Retrieve values by keys
        System.out.println("The Value for key 25 is: " + ht.get(25));
        System.out.println("The Value for key 10 is: " + ht.get(10));
    }
}

Initial Table is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The Value for key 25 is: Welcomes
The Value for key 10 is: Geeks

Example 2: Here, we create a hashtable with string keys and integer values.

// Java program to demonstrate Hashtable get() method
import java.util.*;

public class Geeks {
    
    public static void main(String[] args) {
        
        // Create an empty Hashtable
        Hashtable<String, Integer> ht = new Hashtable<>();

        // Add entries to the Hashtable
        ht.put("Geeks", 10);
        ht.put("4", 15);
        ht.put("Geeks", 20);  
        ht.put("Welcomes", 25);
        ht.put("You", 30);

        System.out.println("Initial table is: " + ht);

        // Retrieve values by keys
        System.out.println("The Value for key Geeks is: " + ht.get("Geeks"));
        System.out.println("The Value for key You is: " + ht.get("You"));
    }
}

Initial table is: {You=30, Welcomes=25, 4=15, Geeks=20}
The Value for key Geeks is: 20
The Value for key You is: 30

Important Points:

• If the key does not exist in the hashtable, get() returns null.
• Duplicate keys are not allowed. If you insert a value with an existing key, it overwrites the previous value.

Note: The same operation can be performed with any type of variation and combination of different data types.

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Article Tags :

• Java
• Java-Collections
• Java-HashTable

Practice Tags :

• Java
• Java-Collections