Removing Another Collection(Removing elements): public boolean removeAll(Collection c) : ArrayList « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. ArrayList

If an element from the passed-in collection is in the list multiple times, all instances are removed.

import java.util.ArrayList;
import java.util.List;

public class MainClass {
  public static void main(String args[]) throws Exception {

    List list = new ArrayList();
    list.add("A");
    list.add("A");
    list.add("B");
    list.add("B");
    list.add("C");
    list.add("C");

    List list2 = new ArrayList();
    list2.add("A");
    list2.add("B");
    list2.add("C");
    list.removeAll(list2);

    System.out.println(list);
  }
}

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