public interface Teacher {
    public Iterator createIterator(); //點(diǎn)名
}

public class ConcreteTeacher implements Teacher{
    private Object[] present = {"張三來(lái)了","李四來(lái)了","王五沒(méi)來(lái)"}; //同學(xué)出勤集合
    public Iterator createIterator(){
        return new ConcreteIterator(this); //新的點(diǎn)名
    }
    public Object getElement(int index){ //得到當(dāng)前同學(xué)的出勤情況
        if(index<present.length){
            return present[index];
        }
        else{
            return null;
        }
    }
    public int getSize(){
        return present.length; //得到同學(xué)出勤集合的大小,也就是說(shuō)要知道班上有多少人
    }
}

public interface Iterator {
    void first(); //第一個(gè)
    void next(); //下一個(gè)
    boolean isDone(); //是否點(diǎn)名完畢
    Object currentItem(); //當(dāng)前同學(xué)的出勤情況
}

public class ConcreteIterator implements Iterator{
    private ConcreteTeacher teacher;
    private int index = 0;
    private int size = 0;
    public ConcreteIterator(ConcreteTeacher teacher){
        this.teacher = teacher;
        size = teacher.getSize(); //得到同學(xué)的數(shù)目
        index = 0;
    }
    public void first(){ //第一個(gè)
        index = 0;
    }
    public void next(){ //下一個(gè)
        if(index<size){
            index++;
        }
    }
    public boolean isDone(){ //是否點(diǎn)名完畢
        return (index>=size);
    }
    public Object currentItem(){ //當(dāng)前同學(xué)的出勤情況
        return teacher.getElement(index);
    }
}

public class Test {
    private Iterator it;
    private Teacher teacher = new ConcreteTeacher();
    public void operation(){
        it = teacher.createIterator(); //老師開(kāi)始點(diǎn)名
        while(!it.isDone()){ //如果沒(méi)點(diǎn)完
            System.out.println(it.currentItem().toString()); //獲得被點(diǎn)到同學(xué)的情況
            it.next(); //點(diǎn)下一個(gè)
        }
    }
    public static void main(String agrs[]){
        Test test = new Test();
        test.operation();
    }
}