The removeAll() method of Java AbstractSet 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: The method throws three types of exception:
- UnsupportedOperationException – This is thrown if the operation is not supported by this set.
- ClassCastException – This is thrown when the class of an element of this set is not compatible with the specified collection.
- NullPointerException – This is thrown when this set contains a null element and the specified collection does not permit null elements, or if the collection is null.
Below are the examples to illustrate the removeAll() method.
Program 1:
// Java program to demonstrate// removeAll() method for Integer value 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 elements 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]
Example 2: For NullPointerException
// Java program to demonstrate// removeAll() method for Integer value 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 = null; // print arrlist2 System.out.println("Collection Elements" + " to be removed : " + arrlist2); // Removing elements 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 : null Exception thrown : java.lang.NullPointerException
