Java.util.Dictionary Class in Java
util.Dictionary is an abstract class, representing a key-value relation and works similar to a map. Given a key you can store values and when needed can retrieve the value back using its key. Thus, it is a list of key-value pair.
Declaration
public abstract class Dictionary extends Object
Constructors:
Dictionary() Sole constructor.
Methods of util.Dictionary Class :
1. put(K key, V value) : java.util.Dictionary.put(K key, V value) adds key-value pair to the dictionary.
Syntax :
public abstract V put(K key, V value) Parameters : -> key -> value Return : key-value pair mapped in the dictionary
2. elements() : java.util.Dictionary.elements() returns value representation in dictionary.
Syntax :
public abstract Enumeration elements() Parameters : -------- Return : value enumeration in dictionary
3. get(Object key) : java.util.Dictionary.get(Object key) returns the value that is mapped with the argumented key in the dictionary.
Syntax :
public abstract V get(Object key) Parameters : key - key whose mapped value we want Return : value mapped with the argumented key
4. isEmpty() : java.util.Dictionary.isEmpty() checks whether the dictionary is empty or not.
Syntax :
public abstract boolean isEmpty() Parameters : ------ Return : true, if there is no key-value relation in the dictionary; else false
5. keys() : java.util.Dictionary.keys() returns key representation in dictionary.
Syntax :
public abstract Enumeration keys() Parameters : -------- Return : key enumeration in dictionary
6. remove(Object key) : java.util.Dictionary.remove(Object key) removes the key-value pair mapped with the argumented key.
Syntax :
public abstract V remove(Object key) Parameters : key : key to be removed Return : value mapped with the key
7. size() : java.util.Dictionary.size() returns the no. of key-value pairs in the Dictionary.
Syntax :
public abstract int size() Parameters : ------- Return : returns the no. of key-value pairs in the Dictionary
Java
// Java Program explaining util.Dictionary class Methods // put(), elements(), get(), isEmpty(), keys() // remove(), size() import java.util.*; public class New_Class { public static void main(String[] args) { // Initializing a Dictionary Dictionary geek = new Hashtable(); // put() method geek.put(" 123 ", "Code"); geek.put(" 456 ", "Program"); // elements() method : for (Enumeration i = geek.elements(); i.hasMoreElements();) { System.out.println("Value in Dictionary : " + i.nextElement()); } // get() method : System.out.println("\nValue at key = 6 : " + geek.get(" 6 ")); System.out.println("Value at key = 456 : " + geek.get(" 123 ")); // isEmpty() method : System.out.println("\nThere is no key-value pair : " + geek.isEmpty() + "\n"); // keys() method : for (Enumeration k = geek.keys(); k.hasMoreElements();) { System.out.println("Keys in Dictionary : " + k.nextElement()); } // remove() method : System.out.println("\nRemove : " + geek.remove(" 123 ")); System.out.println("Check the value of removed key : " + geek.get(" 123 ")); System.out.println("\nSize of Dictionary : " + geek.size()); } } |
Output:
Value in Dictionary : Code Value in Dictionary : Program Value at key = 6 : null Value at key = 456 : Code There is no key-value pair : false Keys in Dictionary : 123 Keys in Dictionary : 456 Remove : Code Check the value of removed key : null Size of Dictionary : 1
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