I have recently seen this JAXB annotation in a project used on a setter. I know from my own experience that #XmlElement can be used on attributes and getters. I'm not sure if this annotation can and should be used on setters, I googled it and couldn't find a clear answer. Please advise.
From Section "8.9 Property & Field" of the JAXB 2.2 specification (see: https://jcp.org/aboutJava/communityprocess/mrel/jsr222/index2.html)
For a property, a given annotation can be applied to either read or
write property but not both.
In other words the annotation can be put on either the get or set method. From my experience the majority of people put the annotation on the get method.
The code clearly says it does work on setters:
public abstract class AbstractInlineAnnotationReaderImpl<T,C,F,M>
implements AnnotationReader<T,C,F,M> {
...
public final <A extends Annotation> A getMethodAnnotation(Class<A> annotation, M getter, M setter, Locatable srcPos) {
A a1 = getter==null?null:getMethodAnnotation(annotation,getter,srcPos);
A a2 = setter==null?null:getMethodAnnotation(annotation,setter,srcPos);
if(a1==null) {
if(a2==null)
return null;
else
return a2;
} else {
if(a2==null)
return a1;
else {
// both are present
getErrorHandler().error(new IllegalAnnotationException(
Messages.DUPLICATE_ANNOTATIONS.format(
annotation.getName(), fullName(getter),fullName(setter)),
a1, a2 ));
// recover by ignoring one of them
return a1;
}
}
}
...
}
However I also could not find a normative reference for this.
Related
I have a problem and I searched a solution about it. Lucky, I red lot of post about it but I'm lost with the explaination I found. The initale problem is coming from a personal project about the polyline of the Xamarin.Forms.Map where the initialization is realized by a binding from the XAML part..
Let me be clear by an example :
I have an object CustomMap.cs which inherit from Xamarin.Forms.Map (This file is in the PCL part -> CustomControl/CustomMap.cs)
public class CustomMap : Map, INotifyPropertyChanged
{
public static readonly BindableProperty PolylineAddressPointsProperty =
BindableProperty.Create(nameof(PolylineAddressPoints), typeof(List<string>), typeof(CustomMap), null);
public List<string> PolylineAddressPoints
{
get { return (List<string>)GetValue(PolylineAddressPointsProperty); }
set
{
SetValue(PolylineAddressPointsProperty, value);
this.GeneratePolylineCoordinatesInner();
}
}
// ...
}
So the Xaml part of the page, where the control is called, looks like that:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:control="clr-namespace:MapPolylineProject.CustomControl;assembly=MapPolylineProject"
x:Class="MapPolylineProject.Page.MainPage">
<ContentPage.Content>
<control:CustomMap x:Name="MapTest" PolylineAddressPoints="{Binding AddressPointList}"
VerticalOptions="Fill" HorizontalOptions="Fill"/>
</ContentPage.Content>
</ContentPage>
The Csharp part:
public partial class MainPage : ContentPage
{
public List<string> AddressPointList { get; set; }
public MainPage()
{
base.BindingContext = this;
AddressPointList = new List<string>()
{
"72230 Ruaudin, France",
"72100 Le Mans, France",
"77500 Chelles, France"
};
InitializeComponent();
//MapTest.PolylineAddressPoints = AddressPointList;
}
}
So, everything is fine if I edit the PolylineAddressPoints from the object instance (if the commented part isnt' commented..), but if I init the value from the XAML (from the InitializeComponent();), it doesn't work, the SetValue, in the Set {}, isn't called..
I then searched on the web about it and get something about the Dependency Properties? or something like that. So I tried some solutions but, from WPF, so some methods, such as DependencyProperty.Register();. So yeah, I can't find the way to solve my problem..
I also though about something, if DependencyProperty.Register(); would exists in Xamarin.Forms, then it means I would have to do it for each values? Because, if every value has to be set by a XAML binding logic, it would not work, I would have to register every value, doesn't it?
I'm sorry if I'm not clear, but I'm so lost about this problem.. Please, do not hesitate to ask for more details, thank in advance !
I finaly got a solution just over here => Ignore the Binding initialization
Copy paste from Stackoverflow. This following answer was given by Stephane Delcroix, thank to him !
There are multiple questions in this:
Why is the property setter never called when using Xaml ?
Am I properly defining my BindableProperty ?
Why is my binding failing ?
Let me answer them in a different order.
Am I properly defining my BindableProperty ?
The BindableProperty declaration is right, but could be improved by using an IList<string>:
public static readonly BindableProperty PolylineAddressPointsProperty =
BindableProperty.Create(nameof(PolylineAddressPoints), typeof(IList<string>), typeof(CustomMap), null);
but the property accessor is wrong, and should only contains this:
public IList<string> PolylineAddressPoints
{
get { return (IList<string>)GetValue(PolylineAddressPointsProperty); }
set { SetValue(PolylineAddressPointsProperty, value); }
}
I'll tell you why while answering the next question. But you want to invoke a method when the property has changed. In order to do that, you have to reference a propertyChanged delegate to CreateBindableProperty, like this:
public static readonly BindableProperty PolylineAddressPointsProperty =
BindableProperty.Create(nameof(PolylineAddressPoints), typeof(IList<string>), typeof(CustomMap), null,
propertyChanged: OnPolyLineAddressPointsPropertyChanged);
And you have to declare that method too:
static void OnPolyLineAddressPointsPropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
((CustomMap)bindable).OnPolyLineAddressPointsPropertyChanged((IList<string>)oldValue, (IList<string>)newValue);
}
void OnPolyLineAddressPointsPropertyChanged(IList<string> oldValue, IList<string> newValue)
{
GeneratePolylineCoordinatesInner();
}
Why is the property setter never called when using Xaml ?
The property, and the property accessors, are only meant to be invoked when accessing the property by code. C# code.
When setting a property with a BindablePrperty backing store from Xaml, the property accessors are bypassed and SetValue() is used directly.
When defining a Binding, both from code or from Xaml, property accessors are again bypassed and SetValue() is used when the property needs to be modified. And when SetValue() is invoked, the propertyChanged delegate is executed after the property has changed (to be complete here, propertyChanging is invoked before the property change).
You might wonder why bother defining the property if the bindable property is only used by xaml, or used in the context of Binding. Well, I said the property accessors weren't invoked, but they are used in the context of Xaml and XamlC:
a [TypeConverter] attribute can be defined on the property, and will be used
with XamlC on, the property signature can be used to infer, at compile time, the Type of the BindableProperty.
So it's a good habit to always declare property accessors for public BindableProperties. ALWAYS.
Why is my binding failing ?
As you're using CustomMap as bot View and ViewModel (I won't tell the Mvvm Police), doing this in your constructor should be enough:
BindingContext = this; //no need to prefix it with base.
As you're doing it already, your Binding should work once you've modified the BindableProperty declaration in the way I explained earlier.
I am new here and this is my first post. I recently got into touch with Jackson and i would like to know if it's possible to get other values than string (or int) while serializing. Pleae be kind if I confuse parts of the terminus.
For example: I have enum
public static enum Type {A, B, C}
in a class like
public class MyClass{
private Type charCat;
public Type getCharCat(){
return this.charCat;
}
public void setCharCat(Type t){
this.charCat = t;
}
}
But if I create an Object (for example with charCat A) and write it into a file I get
...
charCat: "A"
...
How could i get
...
charCat: A
...
?
I tried several tips and solutions, but they did not work.
I am not sure exactly what you are asking for, but the only valid kind of JSON would be
{ "charCat" : "A" }
as all textual values MUST be enclosed in double-quotes. Only values that do not need that are numbers, boolean values (true and false) and null. So serializing value as
{ charCat : A }
would not be valid JSON; so there is no way to get such output.
In my XPages application, I use a managed Java bean (scope = application) for translating strings:
public class Translator extends HashMap<String,String> implements Serializable {
private static final long serialVersionUID = 1L;
public String language = "en";
public Translator() { super(); this.init(null); }
public Translator(String language) { super(); this.init(language); }
public boolean init(String language) {
try {
FacesContext context = FacesContext.getCurrentInstance();
if (language!=null) this.language=language;
Properties data = new Properties();
// load translation strings from properties file in WEB-INF
data.load(new InputStreamReader(context.getExternalContext().getResourceAsStream("WEB-INF/translations_"+this.language+".properties"),"UTF-8"));
super.putAll(new HashMap<String,String>((Map) data));
// serializing the bean to a file on disk > this part of the code is just here to easily test how often the bean is initialized
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("C:\\dump\\Translator_"+this.language+"_"+new Date().getTime()+".ser"));
out.writeObject(this);
out.close();
return true;
}
catch (Exception e) { return false; }
}
public String getLanguage() { return this.language; }
public boolean setLanguage(String language) { return this.init(language); }
// special get function which is more tolerant than HashMap.get
public String get(Object key) {
String s = (String) key;
if (super.containsKey(s)) return super.get(s);
if (super.containsKey(s.toLowerCase())) return super.get(s.toLowerCase());
String s1 = s.substring(0,1);
if (s1.toLowerCase().equals(s1)) {
s1=super.get(s1.toUpperCase()+s.substring(1));
if (s1!=null) return s1.substring(0,1).toLowerCase()+s1.substring(1);
} else {
s1=super.get(s1.toLowerCase()+s.substring(1));
if (s1!=null) return s1.substring(0,1).toUpperCase()+s1.substring(1);
}
return s;
}
}
I use "extends HashMap" because in this way i only have to write "${myTranslatorBean['someText']}" (expression language) to get the translations into my XPage. The problem is that the bean is re-initialized at EVERY complete refresh or page reload. I tested this by serializing the bean to a unique file on the disk at the end of every initialisiation. In my other managed Java beans (which do not use "extends HashMap") this problem does not occur. Can anybody tell me what's wrong with my code? Thanks in advance.
EDIT: The entry for the managed Java bean in the faces-config.xml looks like this:
<managed-bean>
<managed-bean-name>myTranslatorBean</managed-bean-name>
<managed-bean-class>com.ic.Translator</managed-bean-class>
<managed-bean-scope>application</managed-bean-scope>
</managed-bean>
I concur with David about the faces-config entry - if you could post it, that could shine some light on it.
In its absence, I'll take a stab at it: are you using a managed property to set the "language" value for the app. If you are, I suspect that there's a high chance that the runtime calls the setLanguage(...) method excessively. Since you call this.init(...) in that method, that would re-run that method repeatedly as well.
As a point of code style you are free to ignore, over time I (in part due to reading others' opinions) have moved away from extending collection classes directly for this kind of use. What I do instead in this situation is create an object that implements the DataObject interface and then uses a HashMap internally to store cached values. That's part of a larger industry preference called "Composition over inheritance": http://en.wikipedia.org/wiki/Composition_over_inheritance
Just to make sure nothings weird - I suggest you post your faces-config. I use beans all the time but haven't extended HashMap in any of them. You can add a map and still use EL.
Assuming you have a map getter like "getMyMap()" then EL might be:
AppBean.myMap["myKey"]
Truth be told I don't typically use that syntax but I BELIEVE that works. I gave it a quick test and it didn't work as I expected so I'm missing something. I tried something like:
imageData.size["Large"].url
I THINK it didn't work for me because my bean doesn't IMPLEMENT Map. I notice you're EXTENDING HashMap. You might want to try implementing it. I found an interesting post here: http://blog.defrog.nl/2012/04/settings-bean-parameterized-method-call.html
Usually I do still use SSJS to pass Parameters in. It's really not the end of the would using SSJS for that. And I use EL for everything else.
This is an example of passing an object to a custom control and return a TreeSet with EL.
value="#{compositeData.imageSet.allImages}">
Regarding the bigger issue of the bean re-initializing.. That is odd.. I don't do a ton with ApplicationScope. But I suggest you play with the constructor. I'm not sure what you get by calling super() there. I would suggest use a boolean to only run any init code of the boolean wasn't already set. Obviously you then set it in the init code. See what that does.
class Cat{
}
class Tiger extends Cat{
public String getZooAddress(){
return "cityZoo";
};
}
Bean{
public Cat getCat() {
return new Tiger();
}
}
I noticed that #{bean.cat.zooAddress} actually displays "cityZoo". How does it work? I imagined that #{bean.cat} represents a Cat and trying to call getZooAddress() would result in an "property not found" error. Is the container automatically doing the downcasting from Cat to Tiger?
Expression Language utilizes Reflection to find the appropriate property accessor methods on the referenced object.
Here is more information on why Expression Language happens to work this way.
http://today.java.net/pub/a/today/2006/03/07/unified-jsp-jsf-expression-language.html#evaluation-of-el
I have an input (JSF) that should be bound to a property in my bean. This property represents another bean and has an auxiliar method that checks if it's null (I use this method a lot).
The problem is that the binding is failing to get the proper getter and setter. Instead of reading the method that returns the bean, it reads the one that return a boolean value.
The property name is guest. The methods are:
getGuest;
setGuest;
isGuest (checks if guest is null).
JSF is trying to bind the object to isGuest and setGuest, instead of getGuest and setGuest.
I cannot rename isGuest to guestIsNull or something, because that would'nt make to much sense (see the class below).
Finally, my question is: how can I bind this property to the object without renaming my methods? Is it possible?
I also accept suggestions of a better method name (but the meaning must be the same).
Entity
#Entity
public class Passenger {
private Employee employee;
private Guest guest;
public Passenger() {
}
#Transient
public boolean isEmployee() {
return null != this.employee;
}
#Transient
public boolean isGuest() {
return null != this.guest;
}
#OneToOne
public Employee getEmployee() {
return this.employee;
}
public void setEmployee(Employee employee) {
this.employee = employee;
}
#OneToOne
public Guest getGuest() {
return this.guest;
}
public void setGuest(Guest guest) {
this.guest = guest;
}
}
JSF
<h:inputText value="#{passenger.employee}" />
<h:inputText value="#{passenger.guest}" />
Change the method name to isGuestNull.
The problem you're seeing is due to the fact that the EL lets you use getFoo or isFoo as the naming style for getter methods that return booleans.
No, that's not possible. You've to rename them.
Another way is to add a single getter returning an enum which covers all cases.
public enum Type {
GUEST, EMPLOYEE;
}
public Type getType() {
return guest != null ? Type.GUEST
: employee != null ? Type.EMPLOYEE
: null;
}
with
<h:something rendered="#{passenger.type == 'GUEST'}">
Binding to any property using any method is possible and quite easy if you create your custom ELResolver (apidocs). elresolvers are registered in faces config, and they are responsible, given an Object and a String defining a property, for determining the value and type of the given properties (and, as the need arises, to change it).
You could easily write your own ELResolver that would only work for your chosen, single type, and use (for example in a switch statement) the specific methods you need to write and read properties. And for other types it would delegate resolving up the resolver chain. It's really easy to do, much easier than it sounds.
But don't do it. The standard naming pattern of properties predates EL by many years. It is part of the JavaBeans™ standard - one of the very few undisputed standards in Javaland, working everywhere - from ant scripts, through spring configuration files to JSF. Seeing methods isPerson and getPerson in one class actually makes me fill uneasy, as it breaks something I always take for granted and can always count on.
If you like DDD and want to have your method's names pure, use an adapter. It's easy, fun, and gives a couple of additional lines, which is not something to sneer at if you get paid for the ammount of code produced:
public class MyNotReallyBean {
public String checkName() { ... }
public String lookUpLastName() { ... }
public String carefullyAskAboutAge() { ... }
public class BeanAdapter {
public String getName() { return checkName(); }
public String getLastName() { return lookUpLastName(); }
public String getAge() { return carefullyAskAboutAge(); }
}
private static BeanAdapter beanAdapter = new BeanAdapter();
private BeanAdapter getBeanAdapter(){ return beanAdapter; }
}