nonemptyballlist.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;

//  A non-empty ball list.  This list contains a single ball,
// and the rest of the list after the first ball.
public class NonEmptyBallList implements BallListInterface {
    
    private FilledOval oval;
    private BallListInterface rest;
    
    // Create a list out of a single ball and the rest of the list
    public NonEmptyBallList(FilledOval anOval, BallListInterface theRest) {
        oval = anOval;
        rest = theRest;
    }
    
    public boolean isEmpty() {
        return false;
    }
    
    // Return the first element.
    public FilledOval getFirst() {
        return oval;
    }
    
    // Return the ListInterface object that represents the rest 
    // of the list.
    public BallListInterface getRest() {
        return rest;
    }
    
}