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Java Dictionary put() Method with Example

Dictionary Class put() method: Here, we are going to learn about the put() method of Dictionary Class with its syntax and example.
Submitted by Preeti Jain, on February 13, 2020

Dictionary Class put() method

• put() method is available in java.util package.
• put() method is used to put the given key to the given value in this dictionary.
• put() method is a non-static method, it is accessible with the class object and if we try to access the method with the class name then we will get an error.
• put() method may throw an exception at the time of returning value associated with the key.
  NullPointerException: This exception may throw when the given any of the parameters is null exists.

Syntax:

    public abstract Value put(Key k, Value val);

Parameter(s):

• Key k – represents the key value(k).
• Value val – represents the value(val).

Return value:

The return type of this method is Value, it gets value associated with the given key(k) otherwise it returns null when the key did not hold any value.

Example:

// Java program is to demonstrate the example of
// put(Key k, Value val) method of Dictionary

import java.util.*;

public class PutOfDictionary {
    public static void main(String[] args) {
        // Instantiate a Hashtable object
        Dictionary dictionary = new Hashtable();

        // By using put() method is to
        // add an elements in Hashtable 
        dictionary.put(1, "C");
        dictionary.put(2, "C++");
        dictionary.put(3, "JAVA");
        dictionary.put(4, "PHP");
        dictionary.put(5, "SFDC");

        //Display dictionary
        System.out.println("dictionary: " + dictionary);

        // Here we are replacing the value exists
        // on the given key element 3
        dictionary.put(3, "Microservices");

        // Display Modified Dictionary
        System.out.println("dictionary: " + dictionary);
    }
}

Output

dictionary: {5=SFDC, 4=PHP, 3=JAVA, 2=C++, 1=C}
dictionary: {5=SFDC, 4=PHP, 3=Microservices, 2=C++, 1=C}