I started writing a bb app with a menu.
My problem is I don't know how to react if the selected item is clicked. The menu contains some fields in a VerticalFieldManager that is added in a class that extends MainScreen.
I'm sorry for asking such basic stuff, but i googled 1.5 hours now and didnt find a solution or example, Its my very first blackberry app.
Here you go.
This snippet of code defines a new menu item, with a constructor where you specify the label of the menu item and its position on the menu, and a run method which is called when the user clicks on your menu item.
The run method is called on the UI (event) thread, so you are free to update your user interface components from here, or do whatever else you need to do.
I also included a snippet of a screen class that adds the menu item to its menu.
final class MyMenuItem extends MenuItem
{
MyMenuItem()
{
super("Menu item text", 100000, 0);
}
public void run()
{
// The user has clicked on the menu item, and
// this method was called. Do what you need to do.
}
}
final class MyScreen extends MainScreen
{
// ...
protected void makeMenu ( Menu menu, int instance )
{
// let the system build a default menu first
super.makeMenu(menu, instance);
// add your menu item to the screen
menu.add ( new MyMenuItem() );
}
// ...
}
Related
I am working on a blackberry app where one of the requirements is that a ButtonField has to be displayed on all the screens of the app? How can this be accomplished, since the ButtonField has to be added after 2-3 controls?
Toolbar
Logo
ButtonField (All the screens should have this button)
There are many, many ways to solve this problem. Without seeing a visual description of all your screens, it's a little difficult to know exactly which one will work best for you. But, here's one option:
Create a base class that extends MainScreen, and have that base class add the ButtonField, and make sure that all other fields are added above the buttonfield. You can do this by adding the button field in a footer, that is then aligned with the screen's bottom edge using MainScreen#setStatus(Field).
public class BaseScreen extends MainScreen {
private ButtonField _bottomButton;
/** Can only be called by screen subclasses */
protected BaseScreen() {
// call BaseScreen(long)
this(MainScreen.VERTICAL_SCROLL | MainScreen.VERTICAL_SCROLLBAR);
}
protected BaseScreen(long style) {
super(style);
_bottomButton = new ButtonField("Press Me!", ButtonField.CONSUME_CLICK | Field.FIELD_HCENTER);
// TODO: customize your button here ...
Manager footer = new HorizontalFieldManager(Field.USE_ALL_WIDTH);
// just use a vertical field manager to center the bottom button horizontally
Manager spacerVfm = new VerticalFieldManager(Field.USE_ALL_WIDTH | Field.FIELD_HCENTER);
spacerVfm.add(_bottomButton);
footer.add(spacerVfm);
setStatus(footer);
}
/** #return the bottom button, if any subclasses need to access it */
protected ButtonField getBottomButton() {
return _bottomButton;
}
}
Here is then an example of how you'll build all your other screens:
public class BaseTestScreen extends BaseScreen implements FieldChangeListener {
public BaseTestScreen() {
super(MainScreen.VERTICAL_SCROLL | MainScreen.VERTICAL_SCROLLBAR);
HorizontalFieldManager toolbar = new HorizontalFieldManager();
toolbar.add(new ButtonField("One", ButtonField.CONSUME_CLICK));
toolbar.add(new ButtonField("Two", ButtonField.CONSUME_CLICK));
toolbar.add(new ButtonField("Three", ButtonField.CONSUME_CLICK));
add(toolbar);
BitmapField logo = new BitmapField(Bitmap.getBitmapResource("icon.png"));
add(logo);
// do this if you want each different screen to be able to handle the
// bottom button click event. not necessary ... you can choose to
// handle the click in the BaseScreen class itself.
getBottomButton().setChangeListener(this);
}
public void fieldChanged(Field field, int context) {
if (field == getBottomButton()) {
Dialog.alert("Button Clicked!");
}
}
}
As you can see, this makes it possible to handle the button click (differently) in each screen class you create. Or, you can choose to handle the clicks in the base class (BaseScreen). You'll have to decide which makes sense for you. If the same action is always taken when clicking the button, and the base screen doesn't need additional information to handle the click, then just handle the click in BaseScreen. If not, handle in the subclasses as I show.
P.S. One disadvantage of this approach is that it forces all your screen classes to extend a common base class (BaseScreen). In some situations, this can be limiting. However, on BlackBerry, it's not uncommon to have all your screens extend MainScreen anyway. That said, such an architectural decision is impossible for me to comment on without understanding more about your app.
I had to remove all the default menus in blackberry. I have used the following code
protected void makeMenu(Menu menu, int instance) {
// if you want default menu items, uncomment bellow line
// super.makeMenu(menu, instance);
}
But after this, still it was showing the default menu like "Switch Application", for that i have used super(NO_SYSTEM_MENU_ITEMS) in the screen class constructor.
Now all menus are removed, but it is still showing "empty menu" as shown in the image below.
Please let me know how could we remove all menu items and make it empty?
try this in your main screen
public boolean onMenu(int instance) {
// TODO Auto-generated method stub
return false;
}
You can also do that.
public boolean onMenu(int instance) {
return super.onMenu(2);
}
Because for creating menu instance value is 0. So, for any non zero value it doesn't create the menu.
I am working with a BlackBerry application for OS 5.0 and later. The application has one screen which displays at the top of screen a Next and a Previous button. and list field also display in this screen at bottom of these both button
When i click on NEXT Button and Previous Button my List will be updated display data..
When i click on NEXT/PREVIOUS Button i have to display small VerticalfieldManager at the center of the screen with Label "Please wait ..." so after design this screen how can we add more field manager in over the another manager ?
Is there any way to display that Field at the application MainScreen like iPhone AppDelegate screen?
btnState.setChangeListener(new FieldChangeListener() {
public void fieldChanged(Field field, int context)
{ vfm_Middle.add(lblPleasewait);
popup = new PopupScreen(manager);
Thread thread = new Thread()
{
public void run()
{
try
{
Updatelistfield();
stop();
}
catch (InterruptedException e)
{
e.printStackTrace();
}
super.run();
}
public synchronized void stop()
{
// TODO Auto-generated method stub
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run()
{
// TODO Auto-generated method stub
//popup.delete(vfm_Main);
//popup.deleteAll();
//vfm_Main.delete(lblPleasewait);
//lblPleasewait.setText(null);
}
});
}
};
thread.start();
}
});
The proper way of doing that is with a blocking dialog. In BB API this can be done as follows:
VerticalFieldManager manager = new VerticalFieldManager();
manager.add(new LabelField("Please Wait..."));
Screen popup = new PopupScreen(manager);
//Show the pop-up the same way you push a regular screen
This has the advantage of blocking the GUI: if the user pushes the menu or esc key it doesn't have any effect.
If you want to do it in your screen without dialogs, then you can add an empty VerticalFieldManager which you can fill with a label when the message has to be shown. This way, instead of updating the entire screen, only the Manager is refreshed. But then you should write the logic to not letting the user push any button or menu key (or ignoring key press).
I have requirement for having onscreen navigation buttons along with menu items on blackberry. I need to generate menu item commands as onscreen buttons. Is there a way to generate onscreen menu item buttons in Blackberry? i.e On each screen of my application the menu items should be populated as onscreen buttons both having same functionality?
Thank you
The easiest way to accomplish what you're trying to do is write one function then have both the button and the menu item use the same function.
For example:
function doSomething() {
// Your Code Here
}
// In the function building your screen
MenuItem somethingMi = new MenuItem() {
private MenuItem() { super("Do Something",100001, 5); }
public void run() { doSomething() };
}
Button somethingBtn = new ButtonField("Do Something");
somethingBtn.setChangeListener(new FieldChangeListener() {
public void fieldChanged(Field field, int context){
doSomething();
}
}
addMenuItem(somethingMI);
add(somethingBtn);
I want to know how to go from one screen to another by clicking a button that I have added to a MainScreen. I mean just like we do in the Android onClick event for a button - start another startActivity.
In the event handler for the button click, just "push" the screen that you want to appear next, and it will be pushed to the top of the screen stack. For example:
UiApplication.getUiApplication().pushScreen(nextScreen);
This will be better, using FieldChangeListener
button.setChangeListener(new FieldChangeListener()
{
public void fieldChanged(Field field, int context)
{
UiApplication.getUiApplication().pushScreen(new NextScreen());
}
});
This is the alternative way than using,
UiApplication.getUiApplication.involeLater()
{};