Java by API/java.util/AbstractSet

AbstractSet: removeAll(Collection <?> c)

/*
 Output:
true
[I, G, E]
 * */
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class MainClass {
  public static void main(String args[]) {
    String orig[] = { "I", "P", "E", "G", "P" };
    String act[] = { "P", "P", "S" };
    Set origSet = new HashSet(Arrays.asList(orig));
    List actList = Arrays.asList(act);
    System.out.println(origSet.removeAll(actList));
    System.out.println(origSet);
  }
}

extends AbstractSet

/*
 Output:
[V, M, N]


 * */
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
public class MainClass {
  public static void main(String args[]) {
    Set map = new ArraySet();
    map.add("V");
    map.add("M");
    map.add("N");
    System.out.println(map);
  }
}
class ArraySet extends AbstractSet implements Cloneable, Serializable {
  private ArrayList list;
  public ArraySet() {
    list = new ArrayList();
  }
  public ArraySet(Collection col) {
    list = new ArrayList();
    // No need to check for dups if col is a set
    Iterator itor = col.iterator();
    if (col instanceof Set) {
      while (itor.hasNext()) {
        list.add(itor.next());
      }
    } else {
      while (itor.hasNext()) {
        add(itor.next());
      }
    }
  }
  public Iterator iterator() {
    return list.iterator();
  }
  public int size() {
    return list.size();
  }
  public boolean add(Object element) {
    boolean modified;
    if (modified = !list.contains(element)) {
      list.add(element);
    }
    return modified;
  }
  public boolean remove(Object element) {
    return list.remove(element);
  }
  public boolean isEmpty() {
    return list.isEmpty();
  }
  public boolean contains(Object element) {
    return list.contains(element);
  }
  public void clear() {
    list.clear();
  }
  public Object clone() {
    try {
      ArraySet newSet = (ArraySet) super.clone();
      newSet.list = (ArrayList) list.clone();
      return newSet;
    } catch (CloneNotSupportedException e) {
      throw new InternalError();
    }
  }
}