Keeping Or Removing All Elements Of Another Collection From An ArrayList

All elements of a collection can be removed from a list using the list.removeAll(Collection<c>another) method. Similarly, to retain all elements of another collection in a list use list.retainAll(Collection<c>another).

Sample:

import java.util.ArrayList;  
 import java.util.List;  
 public class ArrayListTest {  
      /**  
       * @param args  
       */  
      public static void main(String[] args) {  
           Listlist1=new ArrayList();  
           Listlist2=new ArrayList();  
           list1.add("ONE");  
           list1.add("TWO");  
           list1.add("THREE");  
           list1.add("FOUR");  
           list2.add("TWO");  
           list2.add("FOUR");  
           list1.removeAll(list2);  
           System.out.println("Items in list1 after removing list2 items: "+list1);  
           list1.add("TWO");  
           list1.add("FOUR");  
           list1.retainAll(list2);  
           System.out.println("Items in list1 after retaining all list2 items: "+list1);  
      }  
 }  

Output:

Items in list1 after removing list2 items: [ONE, THREE]
Items in list1 after retaining all list2 items: [TWO, FOUR]