AbstractSequentialList retainAll() method in Java with Example
The retainAll() method of java.util.AbstractSequentialList class is used to retain from this list all of its elements that are contained in the specified collection.
Syntax:
public boolean retainAll(Collection c)
Parameters: This method takes collection c as a parameter containing elements to be retained from this list.
Returns Value: This method returns true if this list changed as a result of the call.
Exception: This method throws NullPointerException if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null.
Below are the examples to illustrate the retainAll() method.
Example 1:
// Java program to demonstrate // retainAll() method for Integer value import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { // Creating object of AbstractSequentialList<Integer> AbstractSequentialList<Integer> arrlist1 = new LinkedList<Integer>(); // Populating arrlist1 arrlist1.add( 1 ); arrlist1.add( 2 ); arrlist1.add( 3 ); arrlist1.add( 4 ); arrlist1.add( 5 ); // print arrlist1 System.out.println( "AbstractSequentialList before " + "retainAll() operation : " + arrlist1); // Creating another object of AbstractSequentialList<Integer> AbstractSequentialList<Integer> arrlist2 = new LinkedList<Integer>(); arrlist2.add( 1 ); arrlist2.add( 2 ); arrlist2.add( 3 ); // print arrlist2 System.out.println( "Collection Elements" + " to be retaind : " + arrlist2); // Removing elements from arrlist // specified in arrlist2 // using retainAll() method arrlist1.retainAll(arrlist2); // print arrlist1 System.out.println( "AbstractSequentialList after " + "retainAll() operation : " + arrlist1); } catch (NullPointerException e) { System.out.println( "Exception thrown : " + e); } } } |
AbstractSequentialList before retainAll() operation : [1, 2, 3, 4, 5] Collection Elements to be retaind : [1, 2, 3] AbstractSequentialList after retainAll() operation : [1, 2, 3]
Example 2: For NullPointerException
// Java program to demonstrate // retainAll() method for Integer value import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { // Creating object of AbstractSequentialList<Integer> AbstractSequentialList<Integer> arrlist1 = new LinkedList<Integer>(); // Populating arrlist1 arrlist1.add( 1 ); arrlist1.add( 2 ); arrlist1.add( 3 ); arrlist1.add( 4 ); arrlist1.add( 5 ); // print arrlist1 System.out.println( "AbstractSequentialList before " + "retainAll() operation : " + arrlist1); // Creating another object of AbstractSequentialList<Integer> AbstractSequentialList<Integer> arrlist2 = null ; // print arrlist2 System.out.println( "Collection Elements" + " to be retaind : " + arrlist2); System.out.println( "\nTrying to pass " + "null as a specified element\n" ); // Removing elements from arrlist // specified in arrlist2 // using retainAll() method arrlist1.retainAll(arrlist2); // print arrlist1 System.out.println( "AbstractSequentialList after " + "retainAll() operation : " + arrlist1); } catch (NullPointerException e) { System.out.println( "Exception thrown : " + e); } } } |
AbstractSequentialList before retainAll() operation : [1, 2, 3, 4, 5] Collection Elements to be retaind : null Trying to pass null as a specified element Exception thrown : java.lang.NullPointerException