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Freemarker: call a static util method from a template file (*.ftl) when no controller

I need to add the following static method in my ftl template.
${statics["java.util.UUID"].randomUUID()}
I don't have a controller class as per the following link
Freemarker: call a static util method from a template file (*.ftl)
Any other solution to add a static method in the FTL template?

You can't solve that purely in the template. Actually, it depends on what other "backdoors" the data-model exposes to the template, but in general you can't do that by design.
If you can add Java classes to the class-path, then by default (otherwise depending on security settings) you can use 'com.example.MyClass'?new() to instantiate a TemplateMethodModel implementation that calls what you need. So there you didn't modify the controller. But still need to be able to add Java classes.

Creating JsonLd + Hydra based Generic Client API in java. Is there any projects exist for reference?

I am creating Client API in Java using :+ Apache Jena FrameWork+ Hydra(for Hypermedia driven) + my private vocab similar to Markus Lanther Event-API Vocab instead of schema.org(for Ontology/Vocabulary part)
Section 1 :
After looking this Markus Lanther EventDemo repo and hydra-java.I found that they are creating classes for each hydra:Class that can break client in future .For example :
A Person class (Person.java)
public class Person
{
String name;
};
But in future requirement name is also a class eg:
public class Name
{
String firstName;
String LastName;
};
So to fulfill this requirement I have to update Person class like this:
public class Person
{
Name name;
};
Question 1:
Is my understanding correct or not of this Section? If yes then what is the way to deal with this part ?
Section 2:
To avoid above problem I created a GenericResource class(GenericResource.java)
public class GenericResource
{
private Model model;
public void addProperty(String propertyName,Object propertyValue)
{
propertyName = "myvocab:"+propertyName;
//Because he will pass propertyName only eg: "name" and I will map it to "myvocab:name"
//Some logic to add propertyName and propertyValue to model
}
public GenericResource retriveProperty(String propertyName)
{
propertyName = "myvocab:"+propertyName;
//Some logic to query and retrieve propertyName data from this Object add it to new GenericResource Object and return
}
public GenericResouce performAction(String actionName,String postData)
{
//Some logic to make http call give response in return
}
}
But again I stuck in lots of problem :
Problem 1: It is not necessary that every propertyName is mapped to myvocab:propertyName. Some may be mapped to some other vocab eg: hydra:propertyName, schema:propertyName, rdfs:propertyName, newVocab:propertyName, etc.
Problem 2: How to validate whether this propertyName belongs to this class ?
Suggestion: Put type field/variable in GenericResource class.And then check supportedProperty in vocab corresponding to that class.To more clarity assume above Person class which is also defined in vocab and having supportedProperty : [name,age,etc] .So my GenericResource have type "Person" and at time of addProperty or some other operation , I will query through vocab for that property is in supportedProperty list or in supportedOperation list in case of performAction().
Is it correct way ? Any other suggestion will be most welcomed?

Question 1: Is my understanding correct or not of this Section? If yes
then what is the way to deal with this part ?
Yes, that seems to be correct. Just because hydra-java decided to creates classes doesn't mean you have to do the same in your implementation though. I would rather write a mapper and annotate an internal class that can then stay stable (you need to update the mapping instead). Your GenericResource approach also looks good btw.
Problem 1: It is not necessary that every propertyName is mapped to
myvocab:propertyName. Some may be mapped to some other vocab eg:
hydra:propertyName, schema:propertyName, rdfs:propertyName,
newVocab:propertyName, etc.
Why don't you store and access the properties with full URLs, i.e., including the vocab? You can of course implement some convenience methods to simplify the work with your vocab.
Problem 2: How to validate whether this propertyName belongs to this
class
Suggestion: Put type field/variable in GenericResource class
JSON-LD's #type in node objects (not in #value objects) corresponds to rdf:type. So simply add it as every other property.
And then check supportedProperty in vocab corresponding to that class.
Please keep in mind that supportedProperty only tells you which properties are known to be supported. It doesn't tell you which aren't. In other words, it is valid to have properties other than the ones listed as supportedProperty on an object/resource.

Ad Q1:
For the flexibility you want, the client has to be prepared for semantic and structural changes.
In HTML that is possible. The server can change the structure of an html form in the way outlined by you, by having a firstName and lastName field rather than just a name field. The client does not break, rather it adjusts its UI, following the new semantics. The trick is that the UI is generated, not fixed.
A client which tries to unmarshal the incoming message into a fixed representation, such as a Java bean, is out of luck, and I do not think there is any solution how you could deserialize into a Java bean and survive a change like yours.
If you do not try to deserialize, but stick to reading and processing the incoming message into a more flexible representation, then you can achieve the kind of evolvability you're after. The client must be able to handle the flexible representation accordingly. It could generate UIs rather than binding data to fixed markup, which means, it makes no assumptions about the semantics and structure of the data. If the client absolutely has to know what a data element means, then the server cannot change the related semantics, it can only add new items with the new semantics while keeping the old ones around.
If there were a way how a server could hand out a new structure with a code-on-demand adapter for existing clients, then the server would gain a lot of evolvability. But I am not aware of any such solutions yet.
Ad Q2:
If your goal is to read an incoming json-ld response into a Jena Model on the client side, please see https://jena.apache.org/documentation/io/rdf-input.html
Model model = ModelFactory.createDefaultModel() ;
String base = null;
model.read(inputStream, base, "JSON-LD");
Thus your client will not break in the sense that it cannot read the incoming response. I think that is what your GenericResource achieves, too. But you could use Jena directly on the client side. Basically, you would avoid unmarshalling into a fixed type.

How to access the Impl classes of Twitter4J?

Using MongoDB, I need to persist objects from Twitter4J. Twitter4J uses interfaces, which are implemented in JSON versions. Example:
The API returns Status (an interface), and Status is implemented as StatusJSONImpl.
I can't save Status to MongoDB, I need to implement StatusJSONImpl.
My issue is, this class StatusJSONImpl is not public (see here) so I can't use it in my code. I tried to download the source of Twitter4J to manually add "public" to StatusJSONImpl: I can do:
Status status = twitter.updateStatus(latestStatus);
String statusStringified = TwitterObjectFactory.getRawJSON(status);
StatusJSONImpl statusImplemented = (StatusJSONImpl) TwitterObjectFactory.createUserList(statusStringified);
SingletonLaunchDB.getMongo().save(statusImplemented);
But I still get a java.lang.IllegalAccessError on the class StatusJSONImpl at run time.
I see from other SA answers that users routinely point other users to this Impl classes... how do they do to use it in their code?
Your help is much appreciated.

Status is serializable. To recover StatusJSONImpl from statusStringified you can write.
JSONObject json = new JSONObject(statusStringified);
Status status = new StatusJSONImpl(json);
The code sample is from StatusSerializationTest.java
I hope this helps.

Use the static factory method on TwitterObjectFactory:
Status status = TwitterObjectFactory.createStatus(statusAsString);
StatusJSONImpl is an implementation detail which library users are not meant deal with. The only thing a user of the library should care about is the contract (the Status interface in this case) which is necessarily public and the library authors promise to fulfill. On the other hand, the concrete classes like StatusJSONImpl are not public on purpose in order to prevent consumers from using them and getting tightly coupled to a specific implementation which may change over time. And from the authors' point of view, by coding to an interface they are then free to return any concrete type they wish as long as it fulfills the contract.
If you check the class that is returned from the factory method, it is StatusJSONImpl. But to reiterate, as a user of the library you should need to know or care about that.
Status status = TwitterObjectFactory.createStatus(statusAsString);
status.getClass(); // class twitter4j.StatusJSONImpl
To understand more about why this is done, you can read about static factory methods.

Manually creating an SqlRowSet

I am using EasyMock and need to set expectations on a method that returns an SqlRowSet. Below is a snippet of code.
// SqlRowSet rowSet = new SqlRowSet(); <-- NOT SURE HOW TO MANUALLY CREATE THIS?
expect(myDao.getCustomerData("All_CUSTOMERS")).andReturn(rowSet);
Anybody know how to manually create an SqlRowSet?

For these types of scenario (i.e. creating a concrete instance of a class is difficult), I typically create a mocked instance. Such as:
SqlRowSet mockedSqlRowSet = createMock(SqlRowSet.class);

Create new child in Dom

I have created test class that created DOM object ,currently I created some attributes
Hard coded ,for example I have create element name structure and for the structure we have attributes,I have created different class that handle the attribute with constructor .
These is the code from the main method
Properties properties = new Properties(document);
Element Property = properties.getProperty();
Properties.setProperty(Property, "product_id","10", "Pro ID");
Type.appendChild(Property);
Properties properties1 = new Properties(document);
Element Property1 = properties1.getProperty();
Properties.setProperty(Property1, "curr","5", "Curr Code");
Type.appendChild(Property1);
The code in the constructor is
public Properties(Document document) {
Property = document.createElement(PROPERTY);
}
As you can see for create new property I have created element property and property1 etc hard coded,which is problematic since what will happen
If I will have table that with list of properties with there data ,how should I handle it?
I am not sure if the constructor is the right solution and my question is how to do that better ?
Thanks!!!

It depends on what you're trying to do.
If you want to create a DOM so that you can test your classes that build DOM's, then simply hard-coding calls will work just fine. You just have to make sure you use enough combinations of calls to thoroughly test you API.
If, on the other hand, you need to create a DOM so that you can then proceed to test your API's that require some sort of DOM input, you might want to consider simply creating those DOM's in the form of XML documents and then using the org.w3c.dom API's to create the DOM from the XML.