balllistinterface.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;

// A list of FilledOvals.  This interface
// captures what is common about all lists.

public interface BallListInterface {
    
    // Returns true if the list is empty
    public boolean isEmpty();
    
    // Returns the first ball in the list
    // pre: the list is not an empty list.
    public FilledOval getFirst();
        
    // Returns the rest of the list, after
    // the first ball.
    // pre: the list is not an empty list.
    public BallListInterface getRest();
    
}