I have created a class extending JComboBox. the model is set like this:
DefaultComboBoxModel<String> readoutModel = new DefaultComboBoxModel<String>(options.toArray(new String[options.size()]));
setModel(readoutModel);
The class implements a listener interface to listen for changes of another class (myModel). These changes might be not relevant at all for that combobox, it might contain selection changes and it might contain content changes for that combobox.
it's easy to change the selection like this:
#Override
public void modelChanged() {
...
setSelectedItem(myModel.getSelectedReadOut());
}
but what if the content of the combobox needs to be changed? shall I replace the combobox model? would I have to interate over the items and compare them with the items present in myModel? I could also remove all items from the combobox model and then add item by item from myModel? (which would also happen if just the selection changes...).
Three options to update your combo box when the underlying data is changed:
Exchange the model (replace with the new one)
Use a generic mutable model (such as DefaultComboBoxModel) and add/remove the data to reflect the changes
Create your own model implementation which is an Adapter to the actual data, and fire change events to reflect changes on the data.
The Adapter solution is quite easy to implement (ComboBoxModel, which is a ListModel), doesn't need to duplicate data and therefore does not need synchronization. Usually the best option, in my option.
Related
I am making a Javafx application and I have a List<String> that I update constantly and I want it to sync with a ListView I have on screen without me needing to update it manually each time. Like binding the ListView by reference. Is this possible? and if so how do I do it? Thanks.
From your question and comments I gather you are trying to do something like:
ObservableList<E> list = ...;
ListView<E> view = ...;
view.itemsProperty().bind(list);
This will not work since bind expects an ObservableValue and ObservableList does not extend that interface. You don't need to bind the items property though. Whatever ObservableList is in the items property will be observed by the ListView for changes (i.e. additions, removals, permutations, and updates1). This means you should be doing something like:
ObservableList<E> list = ...;
ListView<E> view = ...;
view.setItems(list);
And then modifications to list will be reflected in the ListView.
If you need to bind the items property then your ObservableList will either need to be held in an implementation of ObservableValue<ObservableList<E>> or an ObservableListValue<E>.
I recommend reading more about the basics of JavaFX; such as the tutorial on ListView or the documentation.
1. An update change event is fired when a property of an element has been invalidated. In order for an ObservableList to observe the properties of its elements, and thus be capable of firing update events, it must be created with FXCollections.observableArrayList(Callback).
I have a Jframe that contains of two panel.
In one panel named "panelA" , user select a category by selecting an item from JCombobox and then click on "update button". Then I have another panel named "panelB" that contains a Jlist and it showes a list of existing items in that selected category from "panelA".
I have a model class that does the logic part of the application using observer pattern. I send the changes using action listener from panelA after clicking the button to the model class and model class does the work and prepares a list that contains filtered data. Then I need to some how get filtered data show on Jlist content on panelB .
Now My Problem is I don't know which method of the Jlist class updates the content the Jlist. Or it is better to say I don't know which method in Jlist class changes the datalist in Jlist.
I just need a clue.
Sorry if my question is not professional, I am very new at java and programing.
Thanks
If you want a variable-size JList, you should initialize it with JList(ListModel), using a list model that allows adding new elements to the list (like DefaultListModel).
Then you can add new elements like this:
DefaultListModel model = (DefaultListModel)list.getModel();
model.addElement(element);
Use generics if you are using Java 7:
DefaultListModel<MyClass> model = (DefaultListModel<MyClass>)list.getModel();
model.addElement(element);
Where MyClass is the class of the list elements.
hey guys i am new to ZK framework i have a listbox being sorted in the view later i pass the listBox to the controller and i need the items being selected by the user but in the model the items are syncronized with the sorting but in the getSelection array is not syncronized with the sort insted with the original data here is the code.
public void createPDFFromModel(Listbox list,String ref){
BindingListModelList model = (BindingListModelList)list.getModel();
for(int i=0;i<model.size();i++){
System.out.println((((ZamoraListitemAdapter)model.get(i)).getName()));
}
System.out.println("-------------------------------------------");
//Data Printed OK.
java.util.ArrayList<ZamoraListitemAdapter>selections = new java.util.ArrayList<ZamoraListitemAdapter>(model.getSelection());
for(int i=0;i<selections.size();i++){
ZamoraListitemAdapter clazz = (ZamoraListitemAdapter)selections.get(i);
System.out.println(clazz.getName());
//Out of sync with model and with sorting
}
my question is how i get the order of the items after the sort in getSelection model. i am using ZK 5.2.8
You could sort selections after you create it.
There are maybe other/better solutions, but you have
to write what you try to achieveif you need more help.
Reply to Comment
What I mean is
ArrayList<ZamoraListitemAdapter>selections =
new ArrayList<ZamoraListitemAdapter>(model.getSelection());
Collections.sort(selections);
So selections is a List of all your selected items and as long
as you compare the items the same way, they should be in the right order
In case you mean reorder and not sorting...
For me sorting means it is automatic and done by a algorithm.
Reordering instead means you, for example, drag the objects around.
If you mean reordering, and your Model hasn't a way to know if
a item is selected, you probably did something wrong.
Cos zk has got the two classes ListModelList and AbstractListModel
wich implement all methods needed for selection behavior and a custom
Model should, if the programmer wants a selectable Model, inherent
from one of them, cos it's the easiest way.
You should may also read this.
model.getSelection()
returns a Set (no order), instead use
model.getInnerList()
that returns ListModeList
I've been trying to freshen up on my Java knowledge and I've been building a small GUI program and I've been running into a bit of a problem.
Basically, I have a JList which I'm currently populating with strings from an object from one of my classes which implement AbstractListModel which we can call my ItemList class. It contains an ArrayList of objects of the type Item which implements Serializable.
But, what I'd like to do is rather than populate my JList with a bunch of strings I'd like to populate it with some kind of string + JTextField combination so I can see one property of each Item object while also being able to update another property by changing the JTextField.
Now, what I'm looking for is the simplest possible way of doing this, and I am assuming there is a (relatively) simple way to do this since it's such a common thing to want to do in a GUI application (although I wouldn't put it past Java and Swing to make it convoluted and complicated).
So, what is the correct way of doing this?
No need to ever use String objects. Instead:
Put Item objects in the JList.
Add a ListCellRenderer to the list, to show the Item object the most user friendly way.
When the user selects an item, show the details in a different place (I'm thinking a panel with 2 columns of labels and text fields, and two rows - one for each attribute, and perhaps a button to Save)
The edit controls would best be encapsulated in a panel that can then hidden when not required, & put in a variety of places, e.g.
Below the list
In the main part of the GUI
displayed in a JOptionPane or a (modal or not) JDialog
Here is an example of placing the 'view/edit panel' (the file details) below the selection component (the table).
I'd like to know if there is any way that I can update a Jlist after the user adds or removes an item to it and after a user sorts it. Is there any way that I can write a standardized method to update the display based on the order of items in an array or vector, and when the user remove or adds an object from the array that the JList is based on?
Thank you.
Updates should be made to the ListModel, not the Array that was used to create the model.
However, if you want to refresh the list with completely new items or change the order of the items then you create a new DefaultListModel and use the setModel(...) method of the JList to update the view.