Tree.java

package chapter_twenty_seven;

import java.util.Collection;


public interface Tree<E> extends Collection<E>
{
    /**
     * Return true if the element is in the tree
     */
    public boolean search(E e);

    /**
     * Insert element e into the binary tree
     * Return true if the element is inserted successfully
     */
    public boolean insert(E e);

    /**
     * Delete the specified element from the tree
     * 12 * Return true if the element is deleted successfully
     */
    public boolean delete(E e);

    /**
     * Get the number of elements in the tree
     */
    public int getSize();

    /**
     * Inorder traversal from the root
     */
    public default void inorder() { }

    /**
     * Postorder traversal from the root
     */
    public default void postorder() { }

    /**
     * Preorder traversal from the root
     */
    public default void preorder() { }

    @Override
    /** Return true if the tree is empty */
    public default boolean isEmpty()
    {
        return size() == 0;
    }

    @Override
    public default boolean contains(Object e)
    {
        return search((E) e);
    }

    @Override
    public default boolean add(E e)
    {
        return insert(e);
    }

    @Override
    public default boolean remove(Object e)
    {
        return delete((E) e);
    }

    @Override
    public default int size()
    {
        return getSize();
    }

    @Override
    public default boolean containsAll(Collection<?> c)
    {
        // Left as an exercise
        return false;
    }

    @Override
    public default boolean addAll(Collection<? extends E> c)
    {
        // Left as an exercise
        return false;
    }

    @Override
    public default boolean removeAll(Collection<?> c)
    {
        // Left as an exercise
        return false;
    }

    @Override
    public default boolean retainAll(Collection<?> c)
    {
        // Left as an exercise
        return false;
    }

    @Override
    public default Object[] toArray()
    {
        // Left as an exercise
        return null;
    }

    @Override
    public default <T> T[] toArray(T[] array)
    {
        // Left as an exercise
        return null;
    }
}