Trying to create a embedded web page on black berry and cannot set starting url

I’m trying to make an embedded web page on my blackberry app, and I'm having trouble setting the starting URL.

I can only set the URL when I do it from a callback from a TextField. When I try to do it after I push the new screen on, the app no longer works (it does nothing when you try to run it.

The code that works is the 开发者_如何转开发following:

protected boolean keyChar(char key, int status, int time) 
{
    if ( key == Characters.ENTER ) 
    {
        Application.getApplication().invokeLater( new Runnable() 
            {
                public void run() {                     
                    //progressBar.reset("", 0, 100, 0);
                    browserField.requestContent(locationBar.getText().trim());
                } 
            });
        return true;
    } 
    return super.keyChar(key, status, time);
}

When I try to set it automatically after everything is created, nothing happens when I run the app.

Code snippet

public MyApp() 
{
    pushScreen(new BrowserFieldScreen());

    // if I have this here, the app will not open
    Application.getApplication().invokeLater( new Runnable() 
        {
            public void run() {                     
                gBrowserField.requestContent("http://google.com");
            } 
    });
}

The complete program:

package mypackage;

import java.util.Enumeration;
import java.util.Hashtable;

import net.rim.device.api.browser.field.ContentReadEvent;
import net.rim.device.api.browser.field2.BrowserField;
import net.rim.device.api.browser.field2.BrowserFieldListener;
import net.rim.device.api.system.Application;
import net.rim.device.api.system.Characters;
import net.rim.device.api.ui.Color;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Manager;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.GaugeField;
import net.rim.device.api.ui.component.TextField;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;
import net.rim.device.api.ui.decor.BackgroundFactory;

import org.w3c.dom.Document;  

/**
 * BrowserField2ProgressTracker
 * - A BrowserField2 Mini-browser application that keeps track of page-loading progress
 *   and displays progress information to the user.
 */

public class MyApp extends UiApplication {


    static BrowserField gBrowserField;
    public static void main(String[] args){
        MyApp theApp = new MyApp();
        theApp.enterEventDispatcher();
    } 

    public MyApp() {
        pushScreen(new BrowserFieldScreen());
    /*  
        if I have this hear, the ap will not open
        Application.getApplication().invokeLater( new Runnable() {
            public void run() {                     
                gBrowserField.requestContent("http://google.com");
            } 
        });
    }
    */
}

/**
 * BrowserFieldScreen
 * - A screen that contains a location bar, a progress bar, and a browser field
 */
class BrowserFieldScreen extends MainScreen {

    // The location bar where URL will be typed in
    private TextField locationBar;  


    // The BrowserField 
    private BrowserField browserField;


    public BrowserFieldScreen() {
//      progressTracker = new BrowserFieldLoadProgressTracker(10f);
        createGUI();


    }

    private void createGUI() {

        VerticalFieldManager mainManager = new VerticalFieldManager(Field.USE_ALL_WIDTH | Field.USE_ALL_HEIGHT | Manager.VERTICAL_SCROLLBAR | Manager.HORIZONTAL_SCROLLBAR );

        locationBar = new TextField() {

            protected boolean keyChar(char key, int status, int time) {
                if ( key == Characters.ENTER ) {
                    Application.getApplication().invokeLater( new Runnable() {
                        public void run() {                     
                            //progressBar.reset("", 0, 100, 0);
                            browserField.requestContent(locationBar.getText().trim());
                        } 
                    });
                    return true;
                } 
                return super.keyChar(key, status, time);
            } 
        };

        locationBar.setBackground(BackgroundFactory.createSolidBackground(Color.BEIGE));
        locationBar.setText("http://google.com");
        browserField = new BrowserField();

        MyApp.gBrowserField=browserField;
        mainManager.add(locationBar);
        mainManager.add(browserField);
        add(mainManager);   
    } 
}

I don't think you can call invokeLater() until your app, theApp has enter the main event thread. Which is done by calling theApp.enterEventDispatcher()

instead try changing your BrowserFieldScreen constructor to:

public BrowserFieldScreen() {
    //      progressTracker = new BrowserFieldLoadProgressTracker(10f);
    createGUI();
    browserField.requestContent("http://google.com");
}