java迭代器实现树的迭代

实现原理图：

正在学习Java语言迭代器，练习使用迭代器并自定义MyIterator接口达到以上逻辑。
主要思路：把组件分成两种CompositeComponent（复合组件）和AtomicComponent（原组件），它们继承自同一个抽象类（Component，复合组件有子代，子代再继续分两种。

接口

public interface MyIterator {
    boolean hasNext();
 	Component next();
}

抽象类

abstract public class Component {
    protected int id;
    protected String name;
    protected double price;

    public Component(){
    }

    public Component(int id, String name,double price){
        this.id = id;
        this.name = name;
        this.price = price;
    }

    public int getId(){
        return id;
    }

    public void setId(int id){
        this.id=id;
    }

    public String getName(){
        return name;
    }

    public void setName(String name){
        this.name = name;
    }

    public double getPrice(){
        return price;
    }

    public void setPrice(double price){
        this.price = price;
    }

    public abstract void add(Component component) throws UnsupportedOperationException;

    public abstract void remove(Component component) throws UnsupportedOperationException;

    public abstract double calcPrice();

    public abstract MyIterator iterator();

    @Override
    public boolean equals(Object ncp){
        Component component = (Component)ncp;
        if(!super.equals(component))
            return false;
        if(this.id==component.id)
            return true;
        else
            return false;
    }

    @Override
    public String toString(){
        return "id:"+id+", name:"+name+", price"+price;
    }
}

复合组件

public class CompositeComponent extends Component {
    protected ComponentList childs = new ComponentList();

    public CompositeComponent() {

    }

    public CompositeComponent(int id, String name, double price) {
        this.setId(id);
        this.setName(name);
        this.setPrice(price);
    }

    public ComponentList getChildren(){
        return this.childs;
    }

    @Override
    public void add(Component component) throws UnsupportedOperationException {
        childs.add(component);
        calcPrice();
    }

    @Override
    public void remove(Component component) throws UnsupportedOperationException {
        childs.remove(component);
    }

    @Override
    public double calcPrice() {
        double price = 0.0;
        for(Component child:childs){
            price += child.getPrice();
        }
        this.setPrice(price);
        return this.getPrice();
    }

    @Override
    public MyIterator iterator() {
        MyIterator chit = new CompositeIterator(this);
        return chit;
    }

    @Override
    public String toString(){
        StringBuffer components = new StringBuffer();

        components.append("\n"+super.toString());

        for(Component child:childs){
            components.append("\n"+child.toString());
        }
        return components.toString();
    }
}

###原组件

public class AtomicComponent extends Component {
    public AtomicComponent(){

    }
    public AtomicComponent(int id,String name, double price){
        this.setId(id);
        this.setName(name);
        this.setPrice(price);
        toString();
    }

    @Override
    public void add(Component component) throws UnsupportedOperationException {        
    }

    @Override
    public void remove(Component component) throws UnsupportedOperationException {
    }

    @Override
    public double calcPrice() {
        return this.price;
    }

    @Override
    public MyIterator iterator() {
        MyIterator nit =new NullIterator();
        return nit;
    }

    @Override
    public String toString(){
        return super.toString();
    } 
}

复合组件迭代器

public class CompositeIterator implements MyIterator {

    protected ComponentList list =  new ComponentList();
    public CompositeIterator(Component c){
        list.add(c);
    }

    @Override
    public boolean hasNext() {
        if(0== list.size()||list.isEmpty())
            return false;
        else
            return true;
    }

    @Override
    public Component next() {
        if(hasNext()){
            Component c = list.get(0);
            System.out.println("id: "+c.getId()+", name:"+c.getName()+", price:"+c.getPrice());
            if(list.get(0) instanceof CompositeComponent){
                list.addAll( (((CompositeComponent) list.get(0)).getChildren()));
                System.out.println("\nsub-components of "+list.get(0).name+":\n");
            }
            list.remove(0);
            return c;
        }
        else
            return null;
    }   
}

原组件迭代器

public class NullIterator implements MyIterator{

    @Override
    public boolean hasNext() {
        return false;
    }

    @Override
    public Component next() {
        return null;
    }
    
}

最后调用

public class Test {
    public static void main(String[] args) {
        int id = 0;
        //计算对象
        Component computer = new CompositeComponent(id++, "Think Pad",0.0);
        //键盘对象
        Component keyboard = new AtomicComponent(id++, "Keyboard",20.0);
        //鼠标对象
        Component mouse = new AtomicComponent(id++, "Mouse",20.0);
        //显示器对象
        Component monitor = new AtomicComponent(id++,"Monitor",1000.0)
        //主机对象
        Component mainFrame = new CompositeComponent(id++, "Main frame",0.0);
        //硬盘对象
        Component hardDisk = new AtomicComponent(id++, "Hard disk",1000.0);
        //电源对象
        Component powerSupplier = new AtomicComponent(id++, "Power supplier",500.0);
        //主板对象
        Component mainBoard = new CompositeComponent(id++, "Main board",0.0);
        //CPU对象
        Component cpu = new AtomicComponent(id++, "CPU",1500.0);
        //显卡对象
        Component videoCard = new AtomicComponent(id++, "Video card",900.0);
        //网卡对象
        Component networkCard = new AtomicComponent(id++, "Network card",100.0);
        mainBoard.add(cpu);
        mainBoard.add(videoCard);
        mainBoard.add(networkCard);
        mainFrame.add(hardDisk);
        mainFrame.add(powerSupplier);       
        mainFrame.add(mainBoard);        
        computer.add(keyboard);
        computer.add(mouse);
        computer.add(monitor);
        computer.add(mainFrame);

        MyIterator it = computer.iterator();
        while(it.hasNext()){
            Component c = it.next();
        }
    }
}        

新人上路，有更好的方法欢迎讨论。