The AbstractSet class in Java is a part of the Java Collection Framework which implements the Collection interface and extends the AbstractCollection class. It provides a skeletal implementation of the Set interface. This class does not override any of the implementations from the AbstractCollection class, but merely adds implementations for equals() and hashCode() method.
Class Hierarchy:
java.lang.Object
↳ java.util.AbstractCollection<E>
↳ Class AbstractSet<E>
Syntax:
public abstract class AbstractSet<E>
extends AbstractCollection<E>
implements Set<E>
Where E is the type of elements maintained by
this Set.
Constructors in Java AbstractSet:
- protected AbstractSet(): The default constructor, but being protected, it doesn’t allow to create an AbstractSet object.
Below is a sample program to illustrate the java AbstractSet:
// Java code to illustrate AbstractSet import java.util.*; public class GFG1 { public static void main(String[] args) throws Exception { try { // Creating object of AbstractSet<Integer> AbstractSet<Integer> abs_set = new TreeSet<Integer>(); // Populating abs_set abs_set.add(1); abs_set.add(2); abs_set.add(3); abs_set.add(4); abs_set.add(5); // print abs_set System.out.println("AbstractSet: " + abs_set); } catch (Exception e) { System.out.println(e); } } } |
Output:
AbstractSet: [1, 2, 3, 4, 5]
Methods in Java AbstractSet:
- equals(Object o): Compares the specified object with this set for equality.
- hashCode(): Returns the hash code value for this set.
- removeAll(Collection c): Removes from this set all of its elements that are contained in the specified collection (optional operation).
Example:
// Java code to illustrate // methods of AbstractSet import java.util.*; public class GFG1 { public static void main(String[] args) throws Exception { try { // Creating object of AbstractSet<Integer> AbstractSet<Integer> abs_set = new TreeSet<Integer>(); // Populating abs_set abs_set.add(1); abs_set.add(2); abs_set.add(3); abs_set.add(4); abs_set.add(5); // print abs_set System.out.println("AbstractSet before " + "removeAll() operation : " + abs_set); // Creating another object of ArrayList<Integer> Collection<Integer> arrlist2 = new ArrayList<Integer>(); arrlist2.add(1); arrlist2.add(2); arrlist2.add(3); // print arrlist2 System.out.println("Collection Elements" + " to be removed : " + arrlist2); // Removing elemnts from AbstractSet // specified in arrlist2 // using removeAll() method abs_set.removeAll(arrlist2); // print arrlist1 System.out.println("AbstractSet after " + "removeAll() operation : " + abs_set); } catch (NullPointerException e) { System.out.println("Exception thrown : " + e); } } } |
Output:
AbstractSet before removeAll() operation : [1, 2, 3, 4, 5] Collection Elements to be removed : [1, 2, 3] AbstractSet after removeAll() operation : [4, 5]
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/AbstractSet.html
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