.NET to Java Examples

.NET to Java Examples

Java Class Use Example

This is a basic example where we call the simple class defined in JavaClass.java from a .NET application. in the /JVM/java/src/JavaClass.java we have a simple class

public class JavaClass {
    /**
     * This simple method return the "Hello World!!" string
     * * @return "Hello World!!" string
     */
    public String helloWorld()
    {
        return "Hello World from Java!!";
    }
    
    /**
     * This simple method return the sum of two double
     * @param a
     * @param b
     * @return a + b
     */
    public double add(double a, double b)
    {
        return a+b;
    }
    
    /**
     * This simple method return the sin of a double
     * @param a
     * @return sin of a
     */
    public double sin(double a)
    {
        return Math.sin(a);
    }
}

in the \CLR\JavaClassUseExample\program.cs we have the simple .NET C# application

using MASES.JCBridge.C2JBridge;
using System;

namespace JavaClassUseExample
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                new TestClass().Execute();
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                Console.WriteLine("Press any key.");
                Console.ReadKey();
            }
        }

        class TestClass : SetupJVMWrapper
        {
            public override string ClassPath { get { return @"..\..\JVM\Output"; } }

            public void Execute()
            {
                double a = 2;
                double b = 3;
                double c = Math.PI/2;
                var javaClass = DynJVM.JavaClass.@new();
                string hello = javaClass.helloWorld();
                double result = javaClass.add(a, b);
                double sin = javaClass.sin(c);
                Console.WriteLine("{0} {1} + {2} = {3} and sin({4:0.0000000}) = {5:0.00000000}", hello, a, b, result, c, sin);
            }
        }
    }
}

Executing the code we have the following output:

Hello World from Java!! 2 + 3 = 5 and sin(3,1415927) = 1,00000000

JVM Environment Example

This example is an extension of the Java Class Use Example where Environment parameters are configured in the .NET TestClass class.

class TestClass : SetupJVMWrapper
{
    // the following line setup the classpath where JVM will search for classes
    // during runtime it is possible to dynamically add other path using a call like DynJVM.JVMHelper.addPath(<the path to add>);
    public override string ClassPath { get { return @"C:\Program Files\MASES Group\JCOB\Core;..\..\JVM\Java\Output"; } }

    // uncomment the following line and set the correct JRE if the automatic search system fails
    // public override string JVMPath { get { return @"C:\Program Files\Java\jre1.8.0_121\bin\server\jvm.dll"; } }

    // the following code adds all possible switch to the starting JVM.
    // for a complete list see Oracle documentation: https://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html
    public override IEnumerable<KeyValuePair<string, string>> JVMOptions
    {
        get
        {
            var dict = new Dictionary<string, string>();
            dict.Add("-Xmx128M", null); // this line adds a complete argument
            // dict.Add(property, value); // this line adds an argument like -Dproperty = value

            return dict;
        }
    }

    // the following code adds initial packages to the import statement.
    public override IEnumerable<string> JVMPackages
    {
        get
        {
            var list = new List<string>();
            list.Add("java.lang"); // this line adds java.lang.* like you do with "import java.lang.*" in Java
            return list;
        }
    }

    // uncomment and set the following line when you need features of JDK like the use of the compiler
    // public override string JDKHome { get { return @"C:\Program Files\Java\jdk1.8.0_121\"; } }

    public void Execute()
    {
        double a = 2;
        double b = 3;
        double c = Math.PI/2;
        var javaClass = DynJVM.JavaClass.@new();
        string hello = javaClass.helloWorld();
        double result = javaClass.add(a, b);
        double sin = javaClass.sin(c);
        Console.WriteLine("{0} {1} + {2} = {3} and sin({4:0.0000000}) = {5:0.00000000}", hello, a, b, result, c, sin);
        Console.WriteLine("Press Enter to exit");
        Console.ReadLine();
    }
}

ConsoleTest

This is a more complex application that explores the ability of JCOBridge doing the following operations: -Execute java code in the .NET environment using the Dynamic JVM wrapper -Manage shared object -Register CLR object in the Java Virtual Machine side -Use the registered object from the JVM side -Call Methods on the JVM registered class and have the operation reflected to the CLR object -Create dialog in the JVM side and use it from the .NET code

.NET Libraries for use within the Java to .NET Examples

CSharpClass

This library contain a single class that provide double and string operations to be called from JVM.

VBClass

This library contain a single class that provide double and string operations to be called from JVM.

WinFormsTestControl

A Windows Form panel with his complete logic that will be used to demonstrate User Interface Integration in a Java Graphical application.

WPFTestControl

A WPF panel with his complete logic that will be used to demonstrate User Interface Integration in a Java Graphical application.

.NET to Scala examples

Documentation here

Requirements

These examples needs the installation of the .NET Framework version available on JCOBridge website