Working with Java collections from .NET Framework DLL

This article provides an introduction to cross-technology handling of collections. Data structures are one of the essential aspects of every piece of software. Any application constantly process various information, that very often require specific grouping and access strategies. This aspect is addressed by arrays and more advanced collection types. By using the Javonet framework, users gain ability to easily and effectively work with data structures originating from .NET Framework DLL. Every collection from .NET Framework DLL is treated as reference.

Javonet allows you to reference and use modules or packages written in (Java/Kotlin/Groovy/Clojure, C#/VB.NET, Ruby, Perl, Python, JavaScript/TypeScript) like they were created in your technology. If have not yet created your first project check Javonet overview and quick start guides for your technology.

With Javonet you can interact with collections from .NET Framework DLL like they were available in Java but invocation must be performed through Javonet SDK API.

Working with Java lists from .NET Framework DLL

Javonet SDK contains various methods to interact with lists and consume the results in Java:

I code in:
// use activate only once in your app
Javonet.activate("your-license-key");

// create called runtime context
RuntimeContext calledRuntime = Javonet.inMemory().clr();

// get string type
InvocationContext doubleType = calledRuntime.getType("System.Double");

// get generic calls with string type as parameter
InvocationContext listType = calledRuntime.getType("System.Collections.Generic.List`1", doubleType);

// create generic type's instance
InvocationContext list = listType.createInstance().execute();

// invoke instance's method
list.invokeInstanceMethod("AddRange", (Object)new Double[]{1.1, 2.2, 3.3, 4.4, 5.5, 6.6}).execute();

// get element from list
InvocationContext response1 = list.getIndex(3).execute();

// get size of list
InvocationContext response2 = list.getSize().execute();

// get value from response
double result = (double) response1.getValue();
int result2 = (int) response2.getValue();

// write result to console
System.out.println(result);
System.out.println(result2);

In the snippet above, list specific to called technology framework is created.
Then, some elements are added to the list. Finally, this list can be handled through Javonet SDK, f.e. with getIndex method.

Working with Java dictionary from .NET Framework DLL

Javonet SDK contains various methods to interact with dictionaries and consume the results in Java:

I code in:
// use activate only once in your app
Javonet.activate("your-license-key");

// create called runtime context
RuntimeContext calledRuntime = Javonet.inMemory().clr();

// get string and double types
InvocationContext stringType = calledRuntime.getType("System.String");
InvocationContext doubleType = calledRuntime.getType("System.Double");

//get generic calls with string and double types as parameters
InvocationContext dictionaryType = calledRuntime.getType("System.Collections.Generic.Dictionary`2", stringType, doubleType);

// create generic type's instance
InvocationContext dictionary = dictionaryType.createInstance().execute();

// invoke instance's method
dictionary.invokeInstanceMethod("Add", "pi", Math.PI).execute();
dictionary.invokeInstanceMethod("Add", "e", Math.E).execute();
dictionary.invokeInstanceMethod("Add", "c", 299792458.0).execute();

// get element from dictionary
InvocationContext response = dictionary.getIndex("pi").execute();

// get value from response
double result = (double) response.getValue();

// write result to console
System.out.println(result);

In the snippet above, list specific to called technology framework is created.
Then, some elements are added to the list. Finally, this list can be handled through Javonet SDK, f.e. with getIndex method.

The same operation can be performed remotely by just changing the new Runtime Context invocation from in memory to tcp that will create and interact with your .NET Framework DLL objects on any remote node, container or service that hosts Javonet Code Gateway. This way you can preserve the same logic in your application and instantly switch between monolithic and microservices architecture without the need to implement the integration layer based on web services or other remote invocation methods.

Read more about use cases and software architecture scenarios where Javonet runtime bridging technology can support your development process.

Additional references