// CSE 143, Winter 2012
// This class captures common code shared by both the ArrayList and LinkedList.
// An abstract class is a good way to provide a partially implemented class, or
// a partial implementation of an interface.  Notice that the header of this
// class claims to implement the List interface, but the file doesn't write
// all of the methods.
// 
// Java allows this file to compile because it knows that the abstract class
// must be extended to complete it.  If a subclass of AbstractList doesn't
// implement all the rest of the List interface's methods, that subclass will 
// not compile.  

public abstract class AbstractList<E> implements List<E> {
	// Adds the given value to the end of the list.
	public void add(E value) {
		// just call the other add method (to remove redundancy)
		add(size(), value);
	}

	// Returns true if the given value is found in this list.
	public boolean contains(E value) {
		return indexOf(value) >= 0;
	}
	
	// Returns true if the list does not contain any elements.
	public boolean isEmpty() {
		return size() == 0;   // "boolean zen"
	}
}