The removeAll() method of java.util.TreeSet class 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:
// Java program to demonstrate // removeAll() method for Integer value import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// Creating object of TreeSet<Integer>
TreeSet<Integer>
set1 = new TreeSet<Integer>();
// Populating set1
set1.add( 1 );
set1.add( 2 );
set1.add( 3 );
set1.add( 4 );
set1.add( 5 );
// print set1
System.out.println( "TreeSet before "
+ "removeAll() operation : "
+ set1);
// Creating another object of TreeSet<Integer>
TreeSet<Integer>
set2 = new TreeSet<Integer>();
set2.add( 1 );
set2.add( 2 );
set2.add( 3 );
// print set2
System.out.println( "Collection Elements"
+ " to be removed : "
+ set2);
// Removing elements from set
// specified in set2
// using removeAll() method
set1.removeAll(set2);
// print set1
System.out.println( "TreeSet after "
+ "removeAll() operation : "
+ set1);
}
catch (NullPointerException e) {
System.out.println( "Exception thrown : " + e);
}
}
} |
TreeSet before removeAll() operation : [1, 2, 3, 4, 5] Collection Elements to be removed : [1, 2, 3] TreeSet after removeAll() operation : [4, 5]
Example 2: For NullPointerException
// Java program to demonstrate // removeAll() method for Integer value import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// Creating object of TreeSet<Integer>
TreeSet<Integer>
set1 = new TreeSet<Integer>();
// Populating set1
set1.add( 1 );
set1.add( 2 );
set1.add( 3 );
set1.add( 4 );
set1.add( 5 );
// print set1
System.out.println( "TreeSet before "
+ "removeAll() operation : "
+ set1);
// Creating another object of TreeSet<Integer>
TreeSet<Integer>
set2 = null ;
// print set2
System.out.println( "Collection Elements"
+ " to be removed : "
+ set2);
System.out.println( "\nTrying to pass "
+ "null as a specified element\n" );
// Removing elements from set
// specified in set2
// using removeAll() method
set1.removeAll(set2);
// print set1
System.out.println( "TreeSet after "
+ "removeAll() operation : "
+ set1);
}
catch (NullPointerException e) {
System.out.println( "Exception thrown : " + e);
}
}
} |
TreeSet 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