Hashtable
- The underlying data structure is Hashtable
- Insertion order is not preserved and it is based on hash code of the keys.
- Heterogeneous objects are allowed for both keys and values.
- null key (or) null value is not allowed otherwise we will get NullPointerException.
- Duplicate keys are allowed but values can be duplicated.
- Every method present inside Hashtable is syncronized and hence Hashtable object is Thread-safe.
Constructors
1. Hashtable h=new Hashtable();
Creates an empty Hashtable object with default initialcapacity 11 and default fill ratio 0.75.
2. Hashtable h=new Hashtable(int initialcapacity);
3. Hashtable h=new Hashtable(int initialcapacity,float fillratio);
4. Hashtable h=new Hashtable (Map m);
package com.ashok.collections; import java.util.Hashtable; /** * * @author ashok.mariyala * */ public class MyHashTable { public static void main(String[] args) { Hashtable hashtable = new Hashtable(); hashtable.put("Key1", "Ashok"); hashtable.put("Key2", "Vinod"); hashtable.put("Key3", "Dillesh"); hashtable.put("Key4", "Naresh"); hashtable.put("Key5", "Thiru"); System.out.println(hashtable); } }
Hashtable Class