lineariterator.java

来自「国外的数据结构与算法分析用书」· Java 代码 · 共 37 行

package simple;


/**	A basic iterator interface for moving through a collection of items linearly. 
	It utilizes a cursor to keep track of the current item in the sequence.  It
	has methods to move to the front of the collection and to move forward. */
public interface LinearIterator 
{
	/**	Is there a current item? */
	public boolean itemExists();
 
	/**	The current item. 
		PRECONDITION:
			itemExists() */
	public Object item() throws NoCurrentItemUosException;
 
	/**	Is the current position before the start of the structure? */
	public boolean before();
 
	/**	Is the current position after the end of the structure? */
	public boolean after();
 
	/**	Go to the first item in the structure. */
	public void goFirst();

	/**	Advance one item in the data structure. 
		PRECONDITION:
			!after() */
	public void goForth() throws AfterTheEndUosException;

	/**	Move to the position prior to the first element in the structure. */
	public void goBefore();

	/**	Move to the position after the last element in the structure. */
	public void goAfter();
}