Blackberry 如何在弹出式屏幕关闭后调用MainScreen的构造函数

我正在调用一个弹出式屏幕，其中有objectchoicefield，从下拉列表中选择一个数据并在静态变量中设置值。我需要在调用popupscreen的主屏幕的构造函数中读取该值

如何做到这一点？我希望在同一屏幕上重新加载我现在选择的数据

最初，当我启动应用程序时，我看到一个带有一些数据的屏幕，一旦我点击一个图像，我就会调用一个弹出屏幕，在那里我选择一些数据，现在我想在弹出屏幕关闭后，用所选值重新加载一个屏幕

Ascreen

Public AScreen(){
    String timezone_static = MyPopup.ocfDATA;
}
if (field == bitmapField1) {

    UiApplication.getUiApplication().pushScreen(new MyPopup(screen));

}

public class MyPopup extends PopupScreen {
    ObjectChoiceField ocf;
    NativeScreen deligate = null;
    public static String ocfDATA;

    public MyPopup(final NativeScreen deligate) {

        super(new VerticalFieldManager(), Field.FOCUSABLE);
        this.deligate = deligate;
        // this listener 'listens' for any event (see at the bottom)
        FieldListener listener = new FieldListener();

        TimeZone[] zone = TimeZoneUtilities.getAvailableTimeZones();
        ocf = new ObjectChoiceField("Set Timezone", zone);
        ocf.setChangeListener(listener);
        add(ocf);
    }

    class FieldListener implements FieldChangeListener {
        public void fieldChanged(Field f, int context) {

            if (f == ocf) {

                Object ob = ocf.getChoice(ocf.getSelectedIndex());
                String str = ob.toString();
                ocfDATA = str;
                deligate.valueChanged(str);
                Dialog.alert(str);
                close();
            }
        }
    }

---

我正在解释一些如何使用值从一个屏幕导航到另一个屏幕的流程。 这是主屏幕中的一种简单方法

protected void onExposed() {
        String timezone_static = MyPopup.ocfDATA;
    }

否则，您想了解更多信息，从一个地方导航到另一个地方，只需了解以下代码即可

package mypackage;

import java.util.TimeZone;

import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.ButtonField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.ObjectChoiceField;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.PopupScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;
import net.rim.device.api.util.TimeZoneUtilities;

public final class MyScreen extends MainScreen implements FieldChangeListener
{
    private ButtonField btn;
    private LabelField zone_name;
    public MyScreen()
    { 
        //may be you have lots of parameters in constructers those all are in live state only design values you can delete

        CreateGui("Default Zone");// add all your design in this function 
    }
    public void CreateGui(String selcetd_time_zone)
    {
        setTitle(selcetd_time_zone);
        zone_name=new LabelField(selcetd_time_zone, Field.FOCUSABLE);
        btn=new ButtonField("select timezone",Field.FOCUSABLE);
        btn.setChangeListener(this);
        add(btn);
        add(zone_name);
    }
    public void ReloadScreenAccordingToNewZone(String zone_name)
    {
        synchronized (UiApplication.getEventLock()) {
            deleteAll();//clean your GUI
            invalidate();
            CreateGui(zone_name);
        }

    }
    public void fieldChanged(Field field, int context) {
        if(field==btn)
        {
             UiApplication.getUiApplication().pushScreen(new MyPopup(MyScreen.this));
        }
    }
}
class MyPopup extends PopupScreen implements FieldChangeListener{
    ObjectChoiceField ocf;
    MyScreen deligate = null;
    public MyPopup(MyScreen deligate) {
        super(new VerticalFieldManager(), Field.FOCUSABLE);
        this.deligate = deligate;
        TimeZone[] zone = TimeZoneUtilities.getAvailableTimeZones();
        ocf = new ObjectChoiceField("Set Timezone", zone);
        ocf.setChangeListener(this);
        add(ocf);
    }
    public void fieldChanged(Field field, int context) {
        if(field==ocf)
        {
            Object ob = ocf.getChoice(ocf.getSelectedIndex());
            deligate.ReloadScreenAccordingToNewZone(ob.toString());
            close();
        }

    }

}

我的建议是，如果您想从另一个类更新更多的设计，那么只需分离构造函数和设计

像

所有设计都在一个方法中编写，假设CreateGui（）；从构造函数调用此方法； 如果您想重新加载更新设计，只需从OneExposed（）方法调用CreateGui即可

下面是您的屏幕

主屏幕

弹出式屏幕

当您关闭

PopupScreen

时，将调用

onExposed（）

主屏幕的方法

如果您将

String

从

PopupScreen

传递到主屏幕

，则必须在
PopupScreen
中获取一个
静态
变量并设置其值。当您关闭
PopupScreen
时，将调用
主屏幕
的
方法。您必须像在
onExposed（）
方法中那样以静态方式访问它。
String getStringfromPopup=PopupScreen.yourStaticString`

希望它能帮助

package mypackage;

import java.util.TimeZone;

import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.ButtonField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.ObjectChoiceField;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.PopupScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;
import net.rim.device.api.util.TimeZoneUtilities;

public final class MyScreen extends MainScreen implements FieldChangeListener
{
    private ButtonField btn;
    private LabelField zone_name;
    public MyScreen()
    { 
        //may be you have lots of parameters in constructers those all are in live state only design values you can delete

        CreateGui("Default Zone");// add all your design in this function 
    }
    public void CreateGui(String selcetd_time_zone)
    {
        setTitle(selcetd_time_zone);
        zone_name=new LabelField(selcetd_time_zone, Field.FOCUSABLE);
        btn=new ButtonField("select timezone",Field.FOCUSABLE);
        btn.setChangeListener(this);
        add(btn);
        add(zone_name);
    }
    public void ReloadScreenAccordingToNewZone(String zone_name)
    {
        synchronized (UiApplication.getEventLock()) {
            deleteAll();//clean your GUI
            invalidate();
            CreateGui(zone_name);
        }

    }
    public void fieldChanged(Field field, int context) {
        if(field==btn)
        {
             UiApplication.getUiApplication().pushScreen(new MyPopup(MyScreen.this));
        }
    }
}
class MyPopup extends PopupScreen implements FieldChangeListener{
    ObjectChoiceField ocf;
    MyScreen deligate = null;
    public MyPopup(MyScreen deligate) {
        super(new VerticalFieldManager(), Field.FOCUSABLE);
        this.deligate = deligate;
        TimeZone[] zone = TimeZoneUtilities.getAvailableTimeZones();
        ocf = new ObjectChoiceField("Set Timezone", zone);
        ocf.setChangeListener(this);
        add(ocf);
    }
    public void fieldChanged(Field field, int context) {
        if(field==ocf)
        {
            Object ob = ocf.getChoice(ocf.getSelectedIndex());
            deligate.ReloadScreenAccordingToNewZone(ob.toString());
            close();
        }

    }

}