HashSet
HashSet available since Java 1.2
HashSet implements following Interfaces:
HashSet has four constructors:
Characteristics:
Example:
import java.util.*;
class HashSetFlight {
public static void main(String args[]) {
HashSet<String> hs = new HashSet<String>();
hs.add("A");
hs.add("A");
// adding duplicate return false
hs.add("C");
hs.add("D");
hs.add(null);
// null allowed
System.out.println(hs);
}
}
Output:
[null, D, A, C]
HashSet implements following Interfaces:
- Serializable
- Cloneable
- Iterable<E>
- Collection<E>
- Set<E>
HashSet has four constructors:
- HashSet()
- HashSet(Collection c)
- HashSet(int initialCapacity)
- HashSet(int initialCapacity, int loadFactor)
Characteristics:
- The underlying data structure used for HashSet is HashTable.
- Default initial capacity of HashSet is 16.
- Default loat factor of HashSet is 0.75.
- HashSet does not maintain order.
- HashSet doen not allow duplicate elements.
- Once the total elements in the HashSet is reach upto the load factor then the capacity of HashSet increased automatically.
- Elements in the HashSet are stored using the HashCode value of the element.
- HashCode is unique value for each element calculated using the hashing algorithm.
- HashSet allows null element.
Example:
import java.util.*;
class HashSetFlight {
public static void main(String args[]) {
HashSet<String> hs = new HashSet<String>();
hs.add("A");
hs.add("A");
// adding duplicate return false
hs.add("C");
hs.add("D");
hs.add(null);
// null allowed
System.out.println(hs);
}
}
Output:
[null, D, A, C]