迭代器设计模式小例子

来自《Thinking in Java》

多的不说，直接上代码。

interface Selector {
boolean end();
Object current();
void next();
}

public class Sequence {
private Object[] items;
private int next = 0;
public Sequence(int size){
items = new Object[size];
}
public void add(Object x){
if (next < items.length) {
items[next++] = x;
}
}
private class SequenceSelector implements Selector {

    private int i = 0;
    
    public boolean end() {
        return i==items.length;
    }
    
    public Object current() {
        // TODO Auto-generated method stub
        return items[i];
    }
    
    public void next() {
        // TODO Auto-generated method stub
        if (i<items.length) {
            i++;
        }
    }
    
}

public Selector selector(){
    return new SequenceSelector();
}

public static void main(String[] args){
    Sequence sequence = new Sequence(10);
    for (int i = 0; i < 10; i++) {
        sequence.add(Integer.toString(i));
    }
    Selector selector = sequence.selector();
    while (!selector.end()) {
        System.out.println(selector.current() + " ");
        selector.next();
    }
}

这个例子很简单，相信也不需要解释什么了。