Set removeAll() method in Java with Examples
The removeAll() method of java.util.Set interface is used to remove from this set all of its elements that are contained in the specified collection.
Syntax:
public boolean removeAll(Collection c)
Parameters: This method takes collection c as a parameter containing elements to be removed from this set.
Returns Value: This method returns true if this set changed as a result of the call.
Exception: This method throws NullPointerException if this set 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 removeAll() method.
Example 1:
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
Set<Integer> set1 = new HashSet<Integer>();
set1.add( 1 );
set1.add( 2 );
set1.add( 3 );
set1.add( 4 );
set1.add( 5 );
System.out.println( "Set before removeAll() operation : "
+ set1);
Set<Integer> set2 = new HashSet<Integer>();
set2.add( 1 );
set2.add( 2 );
set2.add( 3 );
System.out.println( "Collection Elements to be removed : "
+ set2);
set1.removeAll(set2);
System.out.println( "Set after removeAll() operation : "
+ set1);
}
catch (NullPointerException e) {
System.out.println( "Exception thrown : " + e);
}
}
}
|
Output:
Set before removeAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be removed : [1, 2, 3]
Set after removeAll() operation : [4, 5]
Example 2: For NullPointerException.
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
Set<Integer> set1 = new HashSet<Integer>();
set1.add( 1 );
set1.add( 2 );
set1.add( 3 );
set1.add( 4 );
set1.add( 5 );
System.out.println( "Set before removeAll() operation : "
+ set1);
Set<Integer> set2 = null ;
System.out.println( "Collection Elements to be removed : "
+ set2);
System.out.println( "\nTrying to pass "
+ "null as a specified element\n" );
set1.removeAll(set2);
System.out.println( "Set after removeAll() operation : "
+ set1);
}
catch (NullPointerException e) {
System.out.println( "Exception thrown : " + e);
}
}
}
|
Output:
Set before removeAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be removed : null
Trying to pass null as a specified element
Exception thrown : java.lang.NullPointerException
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Set.html#removeAll(java.util.Collection)
Last Updated :
30 Sep, 2019
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