10 Example of Hashtable in Java – Java Hashtable Tutorial

http://javarevisited.blogspot.com/2012/01/java-hashtable-example-tutorial-code.html

importjava.util.Collection;

import java.util.Enumeration;

import java.util.Hashtable;

import java.util.Set;

publicclass HashtableDemo {

publicstaticvoid main(String args[]) {

// Creating Hashtable for example

Hashtable companies = new Hashtable();

// Java Hashtable example to put object intoHashtable

// put(key, value) is used to insert object into map

companies.put("Google","United States");

companies.put("Nokia","Finland");

companies.put("Sony","Japan");

// Java Hashtable example to get Object fromHashtable

// get(key) method is used to retrieve Objects fromHashtable

companies.get("Google");

// Hashtable containsKey Example

// Use containsKey(Object) method to check if an Object exits as key in

// hashtable

System.out.println("Does hashtable contains Google as key: "

+ companies.containsKey("Google"));

// Hashtable containsValue Example

// just like containsKey(), containsValue returns true ifhashtable

// contains specified object as value

System.out.println("Does hashtable contains Japan as value: "

+ companies.containsValue("Japan"));

// Hashtable enumeration Example

// hashtabl.elements()return enumeration of all hashtable values

Enumeration enumeration = companies.elements();

while (enumeration.hasMoreElements()) {

System.out

.println("hashtable values: " + enumeration.nextElement());

}

// How to check if Hashtable is empty in Java

// use isEmpty method ofhashtable to check emptiness of hashtable in

// Java

System.out.println("Is companies hashtable empty: "

+ companies.isEmpty());

// How to find size ofHashtable in Java

// use hashtable.size() method to find size ofhashtable in Java

System.out.println("Size of hashtable in Java: " + companies.size());

// How to get all values formhashtable in Java

// you can use keySet() method to get a Set of all the keys ofhashtable

// in Java

Set hashtableKeys = companies.keySet();

// you can also get enumeration of all keys by usingmethod keys()

Enumeration hashtableKeysEnum = companies.keys();

// How to get all keys fromhashtable in Java

// There are two ways to get all values formhashtalbe first by using

// Enumeration and second getting values ad Collection

Enumeration hashtableValuesEnum = companies.elements();

CollectionhashtableValues = companies.values();

// Hashtable clear example

// by using clear() we can reuse an existinghashtable, it clears all

// mappings.

companies.clear();

}

}

Output:

Does hashtable contains Google as key: true

Does hashtable contains Japan as value: true

hashtable values: Finland

hashtable values: United States

hashtable values: Japan

Is companies hashtable empty: false

Size of hashtable in Java: 3

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