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What parent to set when calling FieldEditor#setEnabled?

I am building a preference page in Eclipse by extending the FieldEditorPreferencePage class. this page contains 2 fields : 1 BooleanFieldEditor (checkbox) and 1 FileFieldEditor. I would like to disable/enable the file field following the checkbox value.
I went up to something like this (some obvious code is not displayed):
public class PreferencePage extends FieldEditorPreferencePage implements IWorkbenchPreferencePage {
public static final String PREF_KEY_1 = "checkBoxPref";
public static final String PREF_KEY_2 = "filePref";
private FileFieldEditor pathField;
private BooleanFieldEditor yesOrNoField;
private Composite pathFieldParent;
#Override
protected void createFieldEditors() {
this.yesOrNoField = new BooleanFieldEditor(PREF_KEY_1, "Check this box!", getFieldEditorParent());
this.pathFieldParent = getFieldEditorParent();
this.pathField = new FileFieldEditor(PREF_KEY_2, "Path:", this.pathFieldParent);
addField(this.yesOrNoField);
addField(this.pathField);
boolean isChecked = getPreferenceStore().getBoolean(PREF_KEY_1);
updatePathFieldEnablement(! isChecked);
}
/**
* Updates the fields according to entered values
*/
private void updatePathFieldEnablement(boolean enabled) {
this.pathField.setEnabled(enabled, this.pathFieldParent);
}
#SuppressWarnings("boxing")
#Override
public void propertyChange(PropertyChangeEvent event) {
if (event.getProperty().equals(FieldEditor.VALUE) && event.getSource() == this.yesOrNoField) {
updatePathFieldEnablement(! (boolean) event.getNewValue());
}
super.propertyChange(event);
}
}
My question is about this second parameter in FieldEditor#setEnabled. This parameter is the parent composite of the FieldEditor's controls ("Used to create the controls if required" says the javadoc) . At first, I set the value with the return of getFieldEditorParent but then I got an exception "Different parent". So I ended storing it (cf. this.pathFieldParent) and give it back to setEnabled and it works (or it seems to work).
But I am not sure I am doing well, especially because I had to create a member in my class that means nothing to it (and I would have to create many of them if I had many fields to enable/disable).
Do you think I am doing well or is there a better way to provide this parent ? And could you explain to me why *setEnabled" needs it ?
Thanks.

You are using the default FLAT layout for the preference page. When this layout is used each call to getFieldEditorParent generates a new Composite so you have to make just one call and remember the correct parent. Using the GRID layout getFieldEditorParent always returns the same parent. This is the actual code:
protected Composite getFieldEditorParent() {
if (style == FLAT) {
// Create a new parent for each field editor
Composite parent = new Composite(fieldEditorParent, SWT.NULL);
parent.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
return parent;
}
// Just return the parent
return fieldEditorParent;
}
setEnabled does sometimes create a new Label control so it needs to know the correct parent Composite.

Javafx how to access controls of second controller from first controller

I have one question regarding Javafx controller.
Lets say, I have multiple fxml files that are bind together in a main app. Then I have separate controllers for every fxml files. Lets see the following structure
com.par.app
- MainApp.java -> This is the main Application
- FirstController.java
- SecondController.java
com.par.app.view
- First.fxml
- Second.fxml
com.par.app.model
- MyModel -> This has some getter and setter methods.
Now as per above structure, I have a checkbox in First.fxml and a label in Second.fxml.
My Question : How can i set the label text in Second.FXML by checking and unchecking the checkbox in First.FXML , I have tried like this:
// In FirstController.Java
1) Initialize the SecondController
2) Get checkbox from FXMl as , priate CheckBox box1;
3) On initialize(....) method, I have set the event handler, as box1.setOnAction(enableHandle)
4) Finally the event Handler as,
EventHandler<ActionEvent> enableHandle = new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
if (box1.isSelected()) {
secondController.setLabelText("PoP");
} else {
secondController.setText("Gone Wrong");
}
}
};
Similarly, On my second controller I have declared FXML control as,
#FXML
private Label lblTes;
// the method
public void setLabelText(String a)
{
this.lblTes.settest(a);
}
-> The above wont work as it returns Unknown Source.
The next way I tried is by using the MyModel , and using getter and setter methods, But unsuccessful.
I'm sorry my question is really long. I have tried but not succeeded.
What can I do to solve this?
Thanks in advance.
// my model looks like
public class MyModel {
private String btnname;
public String getBtnname() {
return btnname;
}
public void setBtnname(String btnname) {
this.btnname = btnname;
}
}

When you check the check box then in the controller of the FirstView (where you implement an event handler for the check box click) change the label text in your model.
Your model should be bound to your views therefore the label text in your SecondView should be updated.
If you did not bind the model to your views you may use an Observer pattern.
1.Change your model and extend java.util.Observable
public class MyModel extends Observable {
private String btnname;
public String getBtnname() {
return btnname;
}
public void setBtnname(String btnname) {
this.btnname = btnname;
pingObservers()
}
private void pingObservers() {
setChanged();
notifyObservers();
}
}
Register your SecondController as an Observer of the model. When you set the model to the controller add a line similar to this:
model.addObserver(this);
SecondController must implement java.util.Observer.update(...)
void update(Observable o, Object o1) {
// Set the label text with model value
}
In you event handler in the FirstController when you call the setBtnname() method on your model the update() method in the SecondController will be called. There up to you to add the code to change your label text. Since the label is in the view controlled by SecondController you just need to inject a reference of the label in the controller with #FXML annotation.

Refresh JPanel content on tab switch

I'm writing a simple UI just to get the hang of things. I have a tabbed window with two tabs, one has a button that counts up an integer, the other has a text field showing the content of said integer. Or at least that's the plan.
Everything works just fine if I stuff everything into one class. I can access tab 1 from my actionlistener and change the text field in tab 1 from the button press in tab 2. But I don't want my entire program to be in one class, obviously.
And here I have no idea what to do: I need to tell the textfield in the Class Tab1 to change on the button press in the Class Tab2. What's the right thing to do here? My first thought was to hand over an instance of Tab1 in the creation of Tab2, so I could do tab1.changeText(). But that would get messy quickly once I'd get more tabs that interact with each other. So, instead, I want to update the content of the first tab every time it is opened, but I don't know how to do that. And I don't know if that's the right thing to do, either. So, help!
Here's some code. "content" is an instance of Content, a class handling all the logic like adding to the counter.
Main GUI Class:
public class GUI extends JFrame {
//Stuff..
JTabbedPane tabs = new JTabbedPane();
tabs.addTab("One", new Tab1(content));
tabs.addTab("Two", new Tab2(content));
//Stuff..
Tab 1:
public class Tab1 extends JPanel {
public Tab1(Content content) {
JPanel tab1 = new JPanel();
//Stuff..
JTextField tfCount = new JTextField(content.getCounter(), 10);
tab1.add(tfCount);
this.add(tab1);
//Stuff..
Tab 2:
public class Tab2 extends JPanel {
public Tab2(Content content) {
JPanel tab2 = new JPanel();
//Stuff..
JButton btnCount2 = new JButton("Count");
btnCount2.addActionListener(new TestListener(this.content));
tab2.add(btnCount2);
this.add(tab2);
}
private class TestListener implements ActionListener {
Content content;
public TestListener(Content content) {
this.content = content;
}
#Override
public void actionPerformed(ActionEvent e) {
this.content.addToCounter(1);
}
}
Now, if all of that would be in one class (plus subclasses), I could just access tfCount from Tab2 and do tfCount.setText(content.getCounter());. Now tfCount is in a different class, though, and I cannot access it, unless I hand over an instance of Tab1 to Tab2 (like tabs.addTab("Two", new Tab2(content, Tab1);). Couldn't I instead get Tab1 to repaint itself whenever it is opened, like having a method that executes tfCount.setText(content.getCounter()) in Tab1 whenever it is opened, or something along those lines? If so, how do I do that?

With you controls separated in this manner you have a view choices...
You Could...
Share an instance of each "tab" with each of the other tabs, allowing them to either access the others controls or attach listeners across each other. This is very tightly coupled and messy.
The other problem is, does the button really care about the text field or visa versa...
You Could...
Create a simple model that contains the current int value and provides a means to change that value.
The model would have the capacity to fire a ChangeEvent (for example) when the value is changed, which interested parties could listen for and update themselves accordingly.
This decouples the code, reducing the complexity and greatly increasing the flexibility and reuse of various elements of your code.
This is commonly known as an observer pattern and is widely used in Swing.
A possible (listener) example...
For me, I always start with an interface, this describes the absolute minimum requirements that must be meet in order to achieve the required goal. Each tab will want to know the current value, be able to set the next value and listener for changes to the model...
public interface NumberModel {
public int getValue();
public void setValue(int value);
public void addChangeListener(ChangeListener listener);
public void removeChangeListener(ChangeListener listener);
}
An abstract implementation deals with the more "common" implementation details, things that a concrete implementation won't want to have to implement, as it's common enough to all implementations. In this case, that would the listener management...
public abstract class AbstractNumberModel implements NumberModel {
private List<ChangeListener> listeners;
public AbstractNumberModel() {
listeners = new ArrayList<>(25);
}
#Override
public void addChangeListener(ChangeListener listener) {
listeners.add(listener);
}
#Override
public void removeChangeListener(ChangeListener listener) {
listeners.remove(listener);
}
protected ChangeListener[] getChangeListeners() {
// FIFO...
List<ChangeListener> copy = new ArrayList<>(listeners);
Collections.reverse(copy);
return copy.toArray(copy.toArray(new ChangeListener[listeners.size()]));
}
protected void fireStateChanged() {
ChangeListener[] listeners = getChangeListeners();
if (listeners != null && listeners.length > 0) {
ChangeEvent evt = new ChangeEvent(this);
for (ChangeListener listener : listeners) {
listener.stateChanged(evt);
}
}
}
}
And finally, a concrete implementation, which deals with the implementation specific details...
public class DefaultNumberModel extends AbstractNumberModel {
private int value;
public DefaultNumberModel() {
}
public DefaultNumberModel(int value) {
setValue(value);
}
#Override
public int getValue() {
return value;
}
#Override
public void setValue(int num) {
if (num != value) {
value = num;
fireStateChanged();
}
}
}
We could be a slightly more flexible model by doing something like public interface NumberModel<N extends Number> which would allow you define models that could hold Integer, Double, Float and Long for example, but I'll leave that to you.
Each of you tab views will need a setModel(NumberModel) method, so you can pass the model it. In these methods, you will attach a listener to the model and get the current value so that the model and view are in sync.

Prevent some values of SmartGWT IPickTreeItem to be selected

I'm trying to clear the user selected value on a IPickTreeItem.
This is the only solution I've found to restrict the user from selecting some of the Tree root values (not all).
To be more clear, it seems that calling event.cancel() do not stop the event from bubbling.
Am I doing something wrong ?
TreeNode treenode = new TreeNode("root", new TreeNode("Operation A"),
new TreeNode("Operation B"));
final DynamicForm dynamicForm = new DynamicForm();
Tree tree = new Tree();
tree.setRoot(treenode);
final IPickTreeItem pickTreeItem = new IPickTreeItem();
pickTreeItem.setValueTree(tree);
pickTreeItem.addChangeHandler(new ChangeHandler()
{
#Override
public void onChange(ChangeEvent event)
{
pickTreeItem.clearValue() // Not clearing the value
pickTreeItem.setValue((String)null) // Not working neither
event.cancel() // Not seeming to work...
}
});
dynamicForm.setItems(pickTreeItem);
dynamicForm.draw();
This is not working either :
pickTreeItem.setInputTransformer(new FormItemInputTransformer()
{
#Override
public Object transformInput(DynamicForm form, FormItem item,
Object value, Object oldValue)
{
return "Desired New Value (not working)...";
}
});
This is weird because it works using an external Button to clear the value (outside the picktreeitem handler)
Button bt = new Button("click");
bt.addClickHandler(new ClickHandler()
{
#Override
public void onClick(ClickEvent event)
{
pickTreeItem.setValue((Object) null);
}
});
Expected behavior
My Tree :
-aaaa
----bbbb
----cccc
-dddd
----eeee
----ffff
If the user selects "aaaa" the PickTreeItem value should be reverted to the defaultValue ("Choose a value"), optionally inform the user that he cannot pick "aaaa".
The PickTreeItem should accept "dddd" as a valid choosen value.

As with all FormItems, event.cancel() is the correct way to disallow the change. There was a framework level bug that was preventing this from behaving correctly that has now been corrected.
See this thread on the Isomorphic forums

I understand it is not exactly the same with what you are trying to achieve, but you could consider to define a CustomValidator, that reads the selected values and returns false and an appropriate message, when one of the parent values that shouldn't be, is selected. For this to work, you must set pickTreeItem.setCanSelectParentItems(Boolean.TRUE), to allow for parent items to be selected, and pickTreeItem.setValidateOnChange(Boolean.TRUE), to validate the selected values upon selection.

GWT Event Handling best practice

I'm quite new to interface design and struggling to figure out what the best way to handle events is. In the straight forward case of the handler and the (in this case) buttons causing the event being in the same class, that's fine, I get it. The handler can see the buttons so that it can say:
if (event.getSource() == myButton)
and also, the handler is in the same class so it can add tabs to an object local to that class or similar.
Problem: I don't know how I should be dealing with the case when the handlers and event generators are in different classes.
e.g.
From my main layout class I create and show a custom dialog. That dialog is implemented in its own class. Ideally dialog would use the handler from the main layout class (it implements ClickHandler), which would be fine, but my application has a few different ClickEvents. I distinguish between them as above by checking the source. In this case the buttons are in the dialog class though, so I can't simply say:
if (event.getSource() == myDialogbutton)
as myDialogButton is not in scope.
Any hints for how this should work would be appreciated.
D

Perhaps I can help you with my solution ...
I inherited ClickHandler to an own class which is generic. You can give the ClickHandler any kind of object you want and will be able to access it from the method within.
Example:
import com.google.gwt.event.dom.client.ClickHandler;
public abstract class ClickHandlerData<T> implements ClickHandler {
private T data;
public ClickHandlerData(T data)
{
this.data = data;
}
public T getData()
{
return data;
}
public void setData(T data)
{
this.data = data;
}
}
Now, in case of a button:
Button btn = new Button("click me");
btn.addClickHandler(new ClickHandlerData<Button>(btn)) {
public void onClick(ClickEvent event) {
Button btn = getData();
...
}
}
I use this class to pass parameters like Integers or something else to the ClickHandler. For instance:
for (int i=0;i<10;i++)
{
Button btn = new Button("click me");
btn.addClickHandler(new ClickHandlerData<Integer>(i)) {
public void onClick(ClickEvent event) {
Window.alert("you klicked button "+getData());
...
}
}
}
I also do the same for AsyncCallbacks, for Commands, for everything else I need to pass data to.
Hope this helped you a bit.

It appears to me that you are trying to use one listener for multiple buttons, unless several of the buttons have the same function they should have different listeners.
In general you should try to have one listener per function, instead of one listener per "event generator".
If you have for example a logout button, it may have a listener from the LoginStatusWidget (displaying who the client is logged in as) and a listener from an object responsable of notefying the server of the logout.
It will serve to seperate the components from each other.

At first i recommend you to try to collect your Buttons and their ClickHandlers in the same class, but if in your case it is not possible, I have a suggestion to you:
When you are creating your Button you can add some information to them:
Button button = new Button("submit");
button.setLayoutData(someObj);
And then after firing event you can get your Button from event in your ClickHandler and find out which button it is :
Button button = (Button) event.getSource();
MetaData someObj = (MetaData) button.getLayoutData();

Try creating a new listener for each anonymous or serial widget e.g. button in a FlexTable. That way their life cycles are connected and they only refer to each other.
Extend the widget
Give it an id and add it to the constructor [make sure the id is one of a kind]
Implement the listener class.
create a new instance of the listener each time you create an item of the same kind.
I'm guessing there are specific objects connected to the widgets. If so keep a HashMap.
May the force be with you

Can't you just do:
final Button source= new Button("My Button");
button.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
doSomething(source);
}
}
Note the button instance has to be marked final.