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
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
AbstractSequentialList<Integer>
arrlist1 = new LinkedList<Integer>();
arrlist1.add( 1 );
arrlist1.add( 2 );
arrlist1.add( 3 );
arrlist1.add( 4 );
arrlist1.add( 5 );
System.out.println("AbstractSequentialList before "
+ "retainAll() operation : "
+ arrlist1);
AbstractSequentialList<Integer>
arrlist2 = new LinkedList<Integer>();
arrlist2.add( 1 );
arrlist2.add( 2 );
arrlist2.add( 3 );
System.out.println("Collection Elements"
+ " to be retained : "
+ arrlist2);
arrlist1.retainAll(arrlist2);
System.out.println("AbstractSequentialList after "
+ "retainAll() operation : "
+ arrlist1);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
}
}
|
Output:
AbstractSequentialList before retainAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be retained : [1, 2, 3]
AbstractSequentialList after retainAll() operation : [1, 2, 3]
Example 2: For NullPointerException
Java
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
AbstractSequentialList<Integer>
arrlist1 = new LinkedList<Integer>();
arrlist1.add( 1 );
arrlist1.add( 2 );
arrlist1.add( 3 );
arrlist1.add( 4 );
arrlist1.add( 5 );
System.out.println("AbstractSequentialList before "
+ "retainAll() operation : "
+ arrlist1);
AbstractSequentialList<Integer>
arrlist2 = null ;
System.out.println("Collection Elements"
+ " to be retained : "
+ arrlist2);
System.out.println("\nTrying to pass "
+ " null as a specified element\n");
arrlist1.retainAll(arrlist2);
System.out.println("AbstractSequentialList after "
+ "retainAll() operation : "
+ arrlist1);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
}
}
|
Output:
AbstractSequentialList before retainAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be retained : null
Trying to pass null as a specified element
Exception thrown : java.lang.NullPointerException
Last Updated :
12 Dec, 2022
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