Set

Set

It is the child interface of collection. If insertion order is not required & duplicate objects are not allowed. Then we should go for set interface. Set interface doesn’t contain any new method, hence we have to use only collection interface method.

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Constructor

• HasSet h = new HasSet () // creates an empty HasSet object with default initial capacity 16 & default fill ration load factory is 0.75.
• HasSet h = new HasSet ( int initial capacity);
• HasSet h = new HasSet ( int initial capacity, float fill ratio // 0 to 1);
• HasSet h = new HasSet ( collection c)

Load Factor or Fill Ratio:-

import java. util. * ;
Class ExonHasSet
{
public static void main ( String[] args )
           {
            HasSet h = new HasSet ();
            h. add ("B" );
            h. add ("C" );
            h. add ("2" );
            h. add (null);
            h. add (10);
            h. add (K);
            s.o.p ( h.add ( "Z" )); // false
            s.o.p ( h ); // ( in random order elements will be displayed Z,D,K,
                                null,l,C,B,10)
            }
}

Linked HasSet

It is child class of HasSet. It is exactly same as HasSet, except the following differences.

HasSet	Linked HasSet
The underlying data structure is HasSet. Insertion order is not preserved. Introduced in 1.2	The underlying data structure is a combination. Insertion order is preserve. Introduced in version (1.4)

In the above pregame, if we are replacing HasSet with LinkedHasSet is the ( B C Z Null 10 K ), inserting order is preserve. LinkedHasSet & LinkedHasMaps are best suitable to implement cache applications.