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How to create a dictionary in Java

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A Java dictionary is an abstract class that stores key-value pairs. Given a key, its corresponding value can be stored and retrieved as needed; thus, a dictionary is a list of key-value pairs.

The Dictionary object classes are implemented in java.util.

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Creating a dictionary

The first step to creating a dictionary in Java is to choose a class that implements a “key-value pair” interface; a few examples include HashTables, HashMap, and LinkedHashMap.

Syntax

The declaration and initialization of a dictionary follows the syntax below:

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Code

The code snippet below illustrates how to create a dictionary in Java and the usage of a few of the class’s methods:

import java.util.*;
class My_Dictionary
{
public static void main(String[] args)
{
// creating a My HashTable Dictionary
Hashtable<String, String> my_dict = new Hashtable<String, String>();
// Using a few dictionary Class methods
// using put method
my_dict.put("01", "Apple");
my_dict.put("10", "Banana");
// using get() method
System.out.println("\nValue at key = 10 : " + my_dict.get("10"));
System.out.println("Value at key = 11 : " + my_dict.get("11"));
// using isEmpty() method
System.out.println("\nIs my dictionary empty? : " + my_dict.isEmpty() + "\n");
// using remove() method
// remove value at key 10
my_dict.remove("10");
System.out.println("Checking if the removed value exists: " + my_dict.get("10"));
System.out.println("\nSize of my_dict : " + my_dict.size());
}
}

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