An ArrayList implementation that does not accept null values. Attempts to add null to it result in an exception.

NonNullArrayList.java

import java.util.ArrayList;
import java.util.Collection;

/**
 * An {@link ArrayList} implementation that does not accept null values.  Attempts to add
 * <code>null</code> using any of the add methods will result in an {@link IllegalArgumentException}
 * being thrown.  Attempts to addAll from a Collection that contains null elements will also result
 * in an exception.
 * <p/>
 * Here's why: <a href="https://github.com/google/guava/wiki/UsingAndAvoidingNullExplained">UsingAndAvoidingNullExplained</a>
 */
public class NonNullArrayList<T> extends ArrayList<T> {

    public NonNullArrayList() {
        super();
    }

    public NonNullArrayList(int capacity) {
        super(capacity);
    }

    public NonNullArrayList(Collection<? extends T> collection) {
        super(collection);

        for (T item : collection) {
            if (item == null) {
                throw new NullArgumentException();
            }
        }
    }

    @Override
    public boolean add(T object) {
        if (object != null) {
            return super.add(object);
        } else {
            throw new NullArgumentException();
        }
    }

    @Override
    public void add(int index, T object) {
        if (object != null) {
            super.add(index, object);
        } else {
            throw new NullArgumentException();
        }
    }

    @Override
    public boolean addAll(Collection<? extends T> collection) {
        for (T object : collection) {
            if (object != null) {
                this.add(object);
            } else {
                throw new NullArgumentException();
            }
        }
        return super.addAll(collection);
    }

    @Override
    public boolean addAll(int index, Collection<? extends T> collection) {
        boolean changed = false;
        for (T object : collection) {
            if (object != null) {
                add(index, object);
                index++;
                changed = true;
            } else {
                throw new NullArgumentException();
            }
        }
        return changed;
    }

    private static final class NullArgumentException extends IllegalArgumentException {
        public NullArgumentException() {
            super("Cannot add null to a NonNullArrayList");
        }
    }
  }