ascendinglist.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

// Figure 11.18

/** CLass Invariant
 *		An AscendingListOfInt contains objects sorted in ascending order. 
 */
public class AscendingList<ItemType extends Comparable> extends SimpleList<ItemType> {
	/**	post:	this is empty 
	 *			and  iterator == 0	
	 */
	public AscendingList()  {
		super();
	}

	/**	post:	this list == this@pre with z inserted (note that the
	 *				sort property from the class invariant is maintained)
	 *			and  iterator is positioned immediately after
	 *				the newly inserted z 
	 */
	public boolean add(ItemType z)  {
		boolean  found;
		ItemType temp = null;
		reset();
		found = false;
		while ( !found  &&  hasNext() )  {
			temp = next();
			found = (z.compareTo( temp ) <= 0);
		}
		if (!found) {
			super.add(z);
		} else {
			remove();
			super.add(z);
			super.add(temp);
		}
		return true;   // because add is a boolean method
	}
}