The removeAll() method of java.util.concurrent.ConcurrentSkipListSet is an in-built function in Java which returns removes from this set all of its elements that are contained in the specified collection. If the specified collection is also a set, this operation effectively modifies this set so that its value is the asymmetric set difference of the two sets.
Syntax:
public boolean removeAll(Collection c)
Parameter: The function accepts a single parameter c
Return Value: The function returns true if this set changed as a result of the call.
Exception: The function throws the following exceptions:
Below programs illustrate the ConcurrentSkipListSet.removeAll() method:
Program 1:
// Java program to demonstrate removeAll()// method of ConcurrentSkipListSet  import java.util.concurrent.*;import java.util.ArrayList;import java.util.List;  class ConcurrentSkipListSetremoveAllExample1 {    public static void main(String[] args)    {          // Initializing the List        List<Integer> list = new ArrayList<Integer>();          // Adding elements in the list        for (int i = 1; i <= 10; i += 2)            list.add(i);          // Contents of the list        System.out.println("Contents of the list: " + list);          // Initializing the set        ConcurrentSkipListSet<Integer>            set = new ConcurrentSkipListSet<Integer>();          // Adding elements in the set        for (int i = 1; i <= 10; i++)            set.add(i);          // Contents of the set        System.out.println("Contents of the set: " + set);          // Remove all elements from the set which are in the list        set.removeAll(list);          // Contents of the set after removal        System.out.println("Contents of the set after removal: "                           + set);    }} |
Output:
Contents of the list: [1, 3, 5, 7, 9] Contents of the set: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] Contents of the set after removal: [2, 4, 6, 8, 10]
Program 2: Program to show NullPOinterException in removeAll().
// Java program to demonstrate removeAll()// method of ConcurrentSkipListSet  import java.util.concurrent.*;import java.util.ArrayList;import java.util.List;  class ConcurrentSkipListSetremoveAllExample1 {    public static void main(String[] args)    {          // Initializing the set        ConcurrentSkipListSet<Integer>            set = new ConcurrentSkipListSet<Integer>();          // Adding elements in the set        for (int i = 1; i <= 10; i++)            set.add(i);          // Contents of the set        System.out.println("Contents of the set: " + set);          try {            // Remove all elements from the set which are null            set.removeAll(null);        }        catch (Exception e) {            System.out.println("Exception: " + e);        }    }} |
Output:
Contents of the set: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] Exception: java.lang.NullPointerException
Reference:
