java - 如何在圆圈中导航

Question

标题可能不太具有描述性，但我想不出更好的标题。

问题如下:我有一个屏幕 (ScreenOne)，带有指向另一个屏幕 (ScreenTwo) 的链接。ScreenTwo 上有一个返回 ScreenOne 的链接。

我通过自定义 RichTextFields 和自定义 ChangeListener 实现了此功能。

现在的问题是我不断收到 StackOverflowError!有没有办法以这种方式来回导航？

问候马特

public class MyApp extends UiApplication
{
    public static void main(String[] args)
    {
        MyApp theApp = new MyApp();       
        theApp.enterEventDispatcher();
    }

    public MyApp()
    {
        ScreenOne so = ScreenProvider.getInstance().getScreenOne();
        so.initialize();
        ScreenProvider.getInstance().getScreenTwo().initialize();
        pushScreen(so);
    }    
}

public class ScreenOne extends MainScreen {
    MyTextField link;

    public ScreenOne() {
        link = new MyTextField("FirstScreen");
        add(link);
    }

    public void initialize(){
        link.setChangeListener((FieldChangeListener) new MyFieldChangeListener(ScreenProvider.getInstance().getScreenTwo()));
    }
}

public class ScreenTwo extends MainScreen {
    MyTextField link;

    public ScreenTwo() {
        link = new MyTextField("SecondScreen");
        add(link);
    }

    public void initialize(){
        link.setChangeListener((FieldChangeListener) new MyFieldChangeListener(ScreenProvider.getInstance().getScreenOne()));
    }
}

public class MyFieldChangeListener implements FieldChangeListener {

    private Screen nextScreen;

    public MyFieldChangeListener(Screen nextScreen) {
        this.nextScreen = nextScreen;
    }

    public void fieldChanged(Field field, int context) {
        UiApplication.getUiApplication().pushScreen(nextScreen);
    }
}

public class MyTextField extends RichTextField {
    public MyTextField() {
        super();
    }

    public MyTextField(String text) {
        super(text);
    }

    protected boolean touchEvent(TouchEvent message) {
        if (TouchEvent.CLICK == message.getEvent()) {
            FieldChangeListener listener = getChangeListener();
            if (null != listener)
                listener.fieldChanged(this, 1);
        }
        return super.touchEvent(message);
    }
}

public class ScreenProvider {
    private static ScreenProvider instance = null;

    private ScreenProvider(){}

    public static ScreenProvider getInstance() {
        if (instance == null) {
            instance = new ScreenProvider();
        }
        return instance;
    }

    private ScreenOne screenOne = new ScreenOne();
    private ScreenTwo screenTwo = new ScreenTwo();

    public ScreenOne getScreenOne() {
        return screenOne;
    }

    public ScreenTwo getScreenTwo() {
        return screenTwo;
    }
}

Answer 1

ScreenOne 的构造函数创建一个 ScreenTwo 实例，ScreenTwo 的构造函数创建一个 ScreenOne 实例。这里有一个无限循环。