当我使用 postGlobalScreen 推送此屏幕时，为什么屏幕上的按钮不起作用？

Question

我编辑 Blackberry_App_Descriptor.xml 以使我的应用程序是“启动时自动运行”。我的应用程序有 3 个类，myApp、screen1 和 screen2。 MyApp 使用 main 方法来推送 screen1。在 screen1 中有一个按钮来推动屏幕 2。当我手动启动应用程序时它运行正常。 （点击App图标）

问题是：

我使用 RealTimeListener 始终检查每分钟的时间，如果是 1h30，它将推送 screen1，（我使用方法 postGlobalScreen 推送 Screen1）。它推动了成功。但是我可以使用这个屏幕1上的按钮，我点击它并没有推送到屏幕2。

我尝试使用备用入口点检查时间并推送 screen1，但结果相同。

谁能帮我解决和解释清楚这个问题？

// MyApp.java
   public class MyApp extends UiApplication implements RealtimeClockListener
    {
        /**
         * Entry point for application
         * @param args Command line arguments (not used)
         */ 

        public static void main(String[] args)
        {
            // Create a new instance of the application and make the currently
            // running thread the application's event dispatch thread.
            MyApp theApp = new MyApp();  
            theApp.enterEventDispatcher();
        }


        /**
         * Creates a new MyApp object
         */
        public MyApp()
        {        
            // Push a screen onto the UI stack for rendering.
            pushScreen(new Screen1());
            addRealtimeClockListener(this);


        }


        public void clockUpdated() {
            int hour = Calendar.getInstance().get(Calendar.HOUR_OF_DAY);
            int minute = Calendar.getInstance().get(Calendar.MINUTE);
            if(hour==1 && minute == 30){    

                UiApplication.getUiApplication().pushGlobalScreen(new Screen1(),1,UiEngine.GLOBAL_MODAL);           
            }

        }



    }


//Screen1.java
public final class Screen1 extends MainScreen implements FieldChangeListener
{
    /**
     * Creates a new MyScreen object
     */
    ButtonField button;
    public Screen1()
    {        
        button = new ButtonField("Screen 1 ");
        button.setChangeListener(this);
        add(button);


    }
    public void fieldChanged(Field field, int context) {
        if(field==button){
            UiApplication.getUiApplication().pushScreen(new Screen2());

        }

    }

}

//Screen2.java
public final class Screen2 extends MainScreen implements FieldChangeListener
{
    /**
     * Creates a new MyScreen object
     */
    ButtonField button;
    public Screen2()
    {        
        button = new ButtonField("Screen2");
        button.setChangeListener(this);
        add(button);


    }
    public void fieldChanged(Field field, int context) {
        if(field==button){
            UiApplication.getUiApplication().pushScreen(new Screen1());
        }

    }
}

Answer 1

请尝试以下。这里重点讲两点

1)应用程序在后台运行

2)将后台应用程序发送到前台

package mypackage;

import java.util.Calendar;

import net.rim.device.api.system.RealtimeClockListener;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.UiEngine;

public class MyApp extends UiApplication implements RealtimeClockListener
{
    /**
     * Entry point for application
     * @param args Command line arguments (not used)
     */ 
    public  static MyApp theApp=null;
    public static void main(String[] args)
    {
        // Create a new instance of the application and make the currently
        // running thread the application's event dispatch thread.
        theApp = new MyApp();  
        theApp.enterEventDispatcher();
    }


    /**
     * Creates a new MyApp object
     */
    public MyApp()
    {        
        // Push a screen onto the UI stack for rendering.
        pushScreen(new Screen1());
        addRealtimeClockListener(this);
    }


    public void clockUpdated() {
        int hour = Calendar.getInstance().get(Calendar.HOUR_OF_DAY);
        int minute = Calendar.getInstance().get(Calendar.MINUTE);
      //  if(hour==1 && minute == 30){    
        if(!theApp.isForeground())
        {
            UiApplication.getUiApplication().pushGlobalScreen(new Screen1(),1,UiEngine.GLOBAL_MODAL);           
        }

    }
}

screen1.java

package mypackage;

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.container.MainScreen;

public final class Screen1 extends MainScreen implements FieldChangeListener
{
    /**
     * Creates a new MyScreen object
     */
    ButtonField button;
    public Screen1()
    {        
        button = new ButtonField("Screen 1 ");
        button.setChangeListener(this);
        add(button);


    }
    public void fieldChanged(Field field, int context) {
        if(field==button){
            close();
            MyApp.theApp.requestForeground();
            UiApplication.getUiApplication().pushScreen(new Screen2());

        }

    }
    public boolean onClose() {
        MyApp.theApp.requestBackground();
        return true;
    }

}

screen2.java

package mypackage;

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.container.MainScreen;

public final class Screen2 extends MainScreen implements FieldChangeListener
{
    /**
     * Creates a new MyScreen object
     */
    ButtonField button;
    public Screen2()
    {        
        button = new ButtonField("Screen2");
        button.setChangeListener(this);
        add(button);


    }
    public void fieldChanged(Field field, int context) {
        if(field==button){
            UiApplication.getUiApplication().pushScreen(new Screen1());
        }

    }
}