Hashtable class Of Java collection framework implements the Hashtable, which maps the keys to the values. In this class, any null object can be used as a key or as a value. If we compare the Hashtable with the HashMap, you will find the Hashtable is synchronized, whereas HashMap is not synchronized.
Key Points about Hashtable Class
- It Implements Hashtable.
- It is synchronized.
- It does not accept the null key or values.
- It does not allow duplicate keys.
Hashtable ClassConstructors
- Hashtable(): This is the default constructor.
- Hashtable(int size): This creates a hash table that has an initial size specified by size.
- Hashtable(int size, float fillRatio): This version creates a hash table that has an initial size specified by size and
- fills ratio defined by fillRatio. fill ratio: Basically, it determines how the full hash table can be before it is resized upward.and its Value lie between 0.0 to 1.0
- Hashtable(Map m): This creates a hash table that is initialized with the elements in m.
How to Find Element Using containsValue() From Hashtable In Java?
package com.java.Softwaretestingblog;
import java.util.Hashtable;
public class HashtableValueSearch {
public static void main(String[] args) {
// TODO Auto-generated method stub
//www.softwaretestingblog.in
Hashtable<String, String> hm = new Hashtable<String, String>();
//add key-value pair to Hashtable
hm.put("first", "FIRST INSERTED");
hm.put("second", "SECOND INSERTED");
hm.put("third","THIRD INSERTED");
System.out.println(hm);
if(hm.containsValue("SECOND INSERTED"))
{
System.out.println("The Hashtable contains value SECOND INSERTED");
}
else
{
System.out.println("The Hashtable does not contains value SECOND INSERTED");
}
if(hm.containsValue("first"))
{
System.out.println("The Hashtable contains value first");
}
else
{
System.out.println("The Hashtable does not contains value first");
}
}
}Check Also: LinkedHashMap Methods Used In Java
Output:
{third=THIRD INSERTED, second=SECOND INSERTED, first=FIRST INSERTED}
The Hashtable contains value SECOND INSERTED
The Hashtable does not contains value firstPlease write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
Read Value From Hashtable Key In Java: How to Read Value From Hashtable Key In Java With Example?
package com.java.Softwaretestingblog;
import java.util.Hashtable;
import java.util.Set;
public class HashtableKey_Example {
public static void main(String[] args) {
// TODO Auto-generated method stub
//www.softwaretestingblog.in
Hashtable<String, String> hm = new Hashtable<String, String>();
//add key-value pair to Hashtable
hm.put("first", "FIRST INSERTED");
hm.put("second", "SECOND INSERTED");
hm.put("third","THIRD INSERTED");
System.out.println(hm);
Set<String> keys = hm.keySet();
for(String key: keys){
System.out.println("Value of "+key+" is: "+hm.get(key));
}
}
}Check Also: Find Element Using containsValue() From Hashtable
Output:
{third=THIRD INSERTED, second=SECOND INSERTED, first=FIRST INSERTED}
Value of third is: THIRD INSERTED
Value of second is: SECOND INSERTED
Value of first is: FIRST INSERTED
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
Hashtable Operation in Java: Different Hashtable Operation In Java With Example?
package com.softwaretestingo.java.basics;
import java.util.Hashtable;
public class HashtableOperations
{
public static void main(String[] args)
{
//Create hashtable instance
Hashtable<String,String> ht = new Hashtable<String,String>();
//add key-value pair to hashtable
ht.put("first", "FIRST INSERTED");
ht.put("second", "SECOND INSERTED");
ht.put("third","THIRD INSERTED");
System.out.println(ht);
//getting value for the given key from hashtable
System.out.println("Value of key 'second': "+ht.get("second"));
System.out.println("Is Hashtable empty? "+ht.isEmpty());
ht.remove("third");
System.out.println(ht);
System.out.println("Size of the Hashtable: "+ht.size());
}
}
Check Also: Read Value From Hashtable Key In Java
Output:
{third=THIRD INSERTED, second=SECOND INSERTED, first=FIRST INSERTED}
Value of key 'second': SECOND INSERTED
Is Hashtable empty? false
{second=SECOND INSERTED, first=FIRST INSERTED}
Size of the Hashtable: 2Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
Reference: Article
How to Retrieve Values Hashtable Using Keys in Java With Example?
package com.java.Softwaretestingblog;
import java.util.Hashtable;
import java.util.Set;
public class Retrieve_Values_Hashtable_Keys {
public static void main(String[] args) {
// TODO Auto-generated method stub
//www.softwaretestingblog.in
Hashtable<String, String> hm = new Hashtable<String, String>();
//add key-value pair to Hashtable
hm.put("first", "FIRST INSERTED");
hm.put("second", "SECOND INSERTED");
hm.put("third","THIRD INSERTED");
System.out.println(hm);
Set<String> keys = hm.keySet();
for(String key: keys){
System.out.println(key);
}
}
}Check Also: Find First Repeated & Non Repeated Character In Java
Output:
{third=THIRD INSERTED, second=SECOND INSERTED, first=FIRST INSERTED}
third
second
first
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