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JavaFX complex string binding

I'm new to JavaFX and was wondering if the Bindings API allowed an easier way to achieve the following. Consider a model that contains a database that may be null (because the database loads asynchronously) and a view that displays a label status reflecting the state of the database. If it is null it should say something like "Loading..." and if it isn't it should display how many items are in the database. It also would be great if the status could reflect the size of the database as it grows or shrinks.
So far, I understand that I could bind an integer property (size of the database) to the text property of the label by using a converter. This is fine, but I want the label to display more than the number. A localized string like "Loaded {0} items" precisely. And let's not forget that the database may still be null.
This is the solution I have in place
#Override
public void initialize(URL url, ResourceBundle bundle) {
// Initialize label with default value
status();
model.databaseProperty().addListener((obs, old, neu) -> {
// Update label when database is no longer null
status();
// Update label when size of database changes
neu.sizeProperty().addListener(x -> status());
});
}
public void status() {
if (model.database() == null) {
status.setText(bundle.getString("status.loading"));
} else {
String text = bundle.getString("status.ready");
int size = model.database().size();
text = new MessageFormat(text).format(size);
status.setText(text);
}
}
It works, but is there a way to do it with a chain of bindings, or at least part of it? I've seen how powerful (and lenghty) boolean bindings can be but I'm not sure something as flexible is possible with string bindings.

You can use Bindings.when, which is essentially a dynamic if/then binding:*
status.textProperty().bind(
Bindings.when(model.databaseProperty().isNull())
.then(bundle.getString("status.loading"))
.otherwise(
Bindings.selectInteger(model.databaseProperty(), "size").asString(
bundle.getString("status.ready")))
);
However, the above assumes bundle.getString("status.ready") returns a java.util.Formatter string, not a MessageFormat string. In other words, it would need to be "Loaded %,d items" rather than "Loaded {0,number,integer} items".
Bindings doesn’t have built-in support for MessageFormat, but if you really want to stick with MessageFormat (which is a legitimate requirement, as there are things MessageFormat can do which Formatter cannot), you can create a custom binding with Bindings.createStringBinding:
MessageFormat statusFormat = new MessageFormat(bundle.getString("status.ready"));
status.textProperty().bind(
Bindings.when(model.databaseProperty().isNull())
.then(bundle.getString("status.loading"))
.otherwise(
Bindings.createStringBinding(
() -> statusFormat.format(new Object[] { model.getDatabase().getSize() }),
model.databaseProperty(),
Bindings.selectInteger(model.databaseProperty(), "size")))
);
* Actually, it’s more like the ternary ?…: operator.

JavaFX TreeItem css style for different class field

I have TreeView filled by my own tree. In class Node I have field "type" which is one of NodeType. The problem is that I want have style for each type of NodeType, e.g. "type1" text color should be green, "type2" text color should be red. I'm new in javaFX. I found solution by james-d ( https://github.com/james-d/heterogeneous-tree-example ), but in this example css style depends on the class name, how can I make it for class field ?
View of TreeView

My understanding is you want a TreeCell that styles differently depending on the NodeType of the Node contained within the TreeItem of said TreeCell. All via CSS. Am I correct?
Assuming I am correct, there are 2 ways I can think of to accomplish this; both of which work best if there is a small number of known NodeTypes. The first involves the use of PseudoClass and the second uses the same strategy as the JavaFX Chart API.
First Option
Create a custom TreeCell that is tailored to using your Node type (i.e. specify the generic signature appropriately). In this custom TreeCell you declare as many PseudoClass static final fields as you need; one for each NodeType. Then you observe the NodeType of the whatever Node is currently displayed in the TreeCell and update the PseudoClass states accordingly.
Here is an example assuming NodeType is an enum that has two constants: HAPPY and SAD.
public class CustomTreeCell<T extends Node> extends TreeCell<T> {
private static final PseudoClass HAPPY = PseudoClass.getPseudoClass("happy");
private static final PseudoClass SAD = PseudoClass.getPseudoClass("sad");
// this listener will activate/deactivate the appropriate PseudoClass states
private final ChangeListener<NodeType> listener = (obs, oldVal, newVal) -> {
pseudoClassStateChanged(HAPPY, newVal == NodeType.HAPPY);
pseudoClassStateChanged(SAD, newVal == NodeType.SAD);
};
// use a weak listener to avoid a memory leak
private final WeakChangeListener<NodeType> weakListener = /* wrap listener */;
public CustomTreeCell() {
getStyleClass().add("custom-tree-cell");
itemProperty().addListener((obs, oldVal, newVal) -> {
if (oldVal != null) {
oldVal.nodeTypeProperty().removeListener(weakListener);
}
if (newVal != null) {
newVal.nodeTypeProperty().addListener(weakListener);
// need to "observe" the initial NodeType of the new Node item.
// You could call the listener manually to avoid code duplication
pseudoClassStateChanged(HAPPY, newVal.getNodeType() == NodeType.HAPPY);
pseudoClassStateChanged(SAD, newVal.getNodeType() == NodeType.SAD);
} else {
// no item in this cell so deactivate all PseudoClass's
pseudoClassStateChanged(HAPPY, false);
pseudoClassStateChanged(SAD, false);
}
});
}
}
Then in your CSS file you can use:
.custom-tree-cell:happy {
/* style when happy */
}
.custom-tree-cell:sad {
/* style when sad */
}
Second Option
Do what the JavaFX Chart API does when dealing with multiple series of data. What it does is dynamically update the style class of the nodes depending on the series' index in a list (e.g. .line-chart-series-data-<index> <-- probably not exactly this).
/*
* Create a custom TreeCell like in the first option but
* without any of the PseudoClass code. This listener should
* be added/removed from the Node item just like weakListener
* is above.
*/
ChangeListener<NodeType> listener = (obs, oldVal, newVal) -> {
// You have to make sure you keep "cell", "indexed-cell", and "tree-cell"
// in order to keep the basic modena styling.
if (newVal == NodeType.HAPPY) {
getStyleClass().setAll("cell", "indexed-cell", "tree-cell", "custom-tree-cell-happy");
} else if (newVal == NodeType.HAPPY) {
getStyleClass().setAll("cell", "indexed-cell", "tree-cell", "custom-tree-cell-sad");
} else {
getStyleClass().setAll("cell", "indexed-cell", "tree-cell"); // revert to regular TreeCell style
}
};
Then in CSS:
.custom-tree-cell-happy {
/* styles */
}
.custom-tree-cell-sad {
/* styles */
}
Both of these options are really only viable when there is a small set of known types. It might become unmaintainable when you have something like 10+ NodeTypes. It becomes pretty much impossible if the number of NodeTypes is dynamic at runtime.
It might be easier to have NodeType, or some intermediate class/data structure, know what color the text should be and set the color programmatically based on the NodeType.
Note: I quickly typed up the code in my answer and did not test it. There may be compiler errors, runtime exceptions, or logic errors in my code.
Edit
Something else came to mind. My code above assumes that NodeType is held in a property and can be changed during runtime. If NodeType is static (unchanging) for each Node then the code can be vastly simplified. Instead of using any listeners you can simple override the following method declared in javafx.scene.control.Cell:
protected void updateItem(Node item, boolean empty)
This method is called every time a new item is set on the cell. Read the documentation, however, as overriding this method requires certain things from the developer (such as calling the super implementation).

Java Swing - DefaultListModel - Printing all object information, when i only want to print one field

I have this DefaultListModel
DefaultListModel listModel;
//constructor does the right hting... etc.. I skipped over a lot of code
JList jlist_available_items;
....
jlist_available_items= new JList(cartModel); //etc
Everything is working almost perfectly the issue is that
listModel.addElement(product);
if I change it to product.name it will look correctly, but behave wrongly [the object itself won't be accesisble, only the name]
Is adding the object to the view, and all I want to add is the object name.
When I change it to the name it causes all sorts of issues, because I store the objects in a hashmap, and the hashmap uses objects as keys, not the product.name string.
The reason is so that this method can search the hashmap for the right object.
for (Product p : store.database.keySet()) {
if (jlist_available_items.getSelectedValuesList().contains(
(Product) p)) { // if item is selected
cart.addItem(p);
}
}
How can I fix this?? I have been trying to fix it and related bugs for almsot two hours = ( !
Also sample output is
Product [description=descrion test, name=test]
That is what it is printing. I just want it to print the name. = (!
Also the objects are in a hashmap. I can just iterate through the hashmap until an object has the same name value and then use that, but I don't want to. I want a more proper and scalable solution, namely because I am having so much trouble thinking of one.
BY THE WAY! This is a GUI app in Swing! If you want images just ask = )!
EDIT: And now nmy list cell renderer is broken! It was working just a moment ago... = (
#Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
Product product = (Product) value;
return this;
}
}

By default, the toString() method of the objects in the model is called to display the list element. And your Product.toString() method returns Product [description=descrion test, name=test].
If you want to display something else, then use a ListCellRenderer, as explained in the swing tutorial about JList.
EDIT: your renderer has a bug: it doesn't set the text of the returned component (which is a JLabel). It should be:
Product product = (Product) value;
setText(product.getName());
return this;

Prepend beginning to object name and set text in java

I'm trying to pick up java quickly and looking for a way to set the text of a number of labels in my java app.
What I have is a java app that starts\stops\checks status of windows services. I have a method, which is passed an array of these service names and each of these services has a corresponding label that contains it's status. For example, DummyService1 is contained in the array and there is a label called txt_DummyService1. My method (short version) does the following
public static void Checker(String Array[])
{
//check status of DummyService1
"txt_"+DummyService.Text = "started";
}
I realize that this isn't the way that you do this, but could anybody help me out with the best way to do this?

There's no way to generate a "variable" name from a String in this manner. Yes, you might use reflection, but that already rasies questions about the quality of the design.
Instead. Place each label into a Map keyed by it's name.
private Map<String, JLabel> labelLookup = new HashMap<>(25); // Instance variable.
In you constructor (or where ever you build your UI), add each label to the Map.
/* Other UI code */
labelLookup.put("DummyService1", txt_DummyService1);
Now, when you need to do you changes, simply look up the label by it's name
// You had better have a VERY good reason for making this static...
public void checker(String services[])
{
for (String service : services) {
JLabel label = labelLookup.get(service);
if (label != null) {
label.setText("Started");
}
}
}
For example...

Actually I was looking for something more like the following
public static void Checker()
{
try
{
Object Instance = getClass().getDeclaredField("txt_DummyService").get(this);
Method m = Instance.getClass().getMethod("setText",String.class);
m.invoke(Instance,"started");
}
catch(Exception e)
{
//exception handling
}
}

You cannot manipulate variable names at runtime since these are only available to the compiler. One solution to your problem is to keep a Map<String, JLabel> (assuming you are using JLabel and not some other component) to associate a name with each JLabel. I'm sure there are several other possible solutions depending on the exact design of your code.

Java ADF using stored parameter from data control class with stacked bar-graph

I am working with a dual-axis stacked bar graph (ADF component) using a List of objects containing the x-axis labels and the values to be displayed/stacked in the graph.
I'm relatively new to ADF & EJB so I want to apologise in advance if this question seems rudimentary to any of you.
I should mention that I'm using JDeveloper 11.1.1.5
I'm having a hard time with retrieving the value from a variable to be assigned to a property of the bar graph I'm trying to display on my JSF page.
I have briefly summarised the logic below for reference.
The data/list is retrieved from the following class data control:
public class ActivityChart {
private Double axisScale;
public ActivityChart() {
super();
axisScale = 0.0;
}
public List<ActivityDTO> getActivityDetail(List<String> businessUnits) {
List<ActivityDTO> returnNewList = new ArrayList<ActivityDTO>();
List<TransactionDTO> dataList = new ArrayList<TransactionDTO>();
TransactionSessionBean transBean = lookupTransactionSessionBean();
if (businessUnits != null && !businessUnits.isEmpty()){
dataList = transBean.getActivityData(SystemUtil.getCurrentUser(), businessUnits);
returnNewList = processTransactions(dataList);
axisScale = calcAxisScale(returnNewList);
}
return returnNewList;
}
...
The TransactionDTO object is basically a mirror of the entity object to store the fields from the queried db transactions.
The ActivityDTO object contains a String value (x-axis label) and 3 Double values for the values required for the bar graph.
What I'm trying to do is dynamically set the scale for the 2 y-axes (I'm using a dual-axis stacked bar graph) because the auto calculated values are not aligned.
Right now I've got the two relevant elements of the bar graph hard-coded with a specific axis value:
<dvt:y1Axis axisMaxAutoScaled="false" axisMaxValue="100.0"/>
<dvt:y2Axis axisMaxAutoScaled="false" axisMaxValue="100.0"/>
The value I want to use for the Y-axis is calculated and stored in the "axisScale" variable in the above class.
Really at a loss of how to move forward from here.
Would very much appreciate any guidance/direction offered.
Thanks,
Karim

Add a getter for axisScale & regenerate your data control. Add a binding for axisScale to your page & then use that as your maximum value.
The pageDef:
<attributeValues IterBinding="ActivityChartIterator" id="axisScale">
<AttrNames>
<Item Value="axisScale"/>
</AttrNames>
</attributeValues>
The page:
<dvt:y1Axis axisMaxValue="#{bindings.axisScale.attributeValue}" axisMaxAutoScaled="false"/>
<dvt:y2Axis axisMaxValue="#{bindings.axisScale.attributeValue}" axisMaxAutoScaled="false"/>