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AndroidJavaClass and AndroidJavaObject for C# .Net Framework

I have code in Unity that calls a function programmed in Java for Android using AndroidJavaClass and AndroidJavaObject and I would like to pass this code to a dll in C# .Net but I can't find an easy way to call Java functions using C# .Net since the AndroidJavaObject and AndroidJavaClass classes are exclusive to the Unity dll, here is an example of my code:
Java (Android):
public class DeviceManager {
public interface DeviceListener {
void DoSomething();
}
private DeviceListener deviceListener;
public DeviceManager(DeviceListener deviceListener){
this.deviceListener = deviceListener;
}
public String[] getSomeData(){
return new String[]{};
}
}
C# (Unity):
public class DeviceListener : AndroidJavaProxy
{
DeviceManager deviceManager;
public DeviceListener(DeviceManager manager) : base("com.myapp.DeviceManager$DeviceListener")
{
this.deviceManager = manager;
}
public void DoSomething();
}
public class DeviceManager
{
private AndroidJavaObject jo;
public DeviceManager(){
jo = new AndroidJavaObject("com.myapp.DeviceManager", new DeviceListener(this));
}
public string[] GetData(){
AndroidJavaObject returnedData = jo.Call<AndroidJavaObject>("getSomeData");
return AndroidJNIHelper.ConvertFromJNIArray<string[]>(returnedData.GetRawObject());
}
}
What is the best way to do that example in C# .Net instead of Unity?
EDIT: my main question is related to know how to get objects and call functions from an .aar file in .NET Framework inside a dll C# file for Unity
EDIT 2: I found some information about Xamarin, maybe that is what I am looking for?: https://github.com/xamarin/monodroid-samples/tree/master/JavaIntegration/AarBinding But even though I could link an .aar file to a dll in C# that doesn't quite answer my question in the best way to create a code that works the same as the example described above
EDIT 3: Currently, to solve this problem, I am using the UnityEngine .dll in my Visual Studio project but I want to generate a .dll for use in other graphics engines so I would like to be able to find a different solution than using Unity's own .dll for solve this problem, hence I mentioned Xamarin since it is a good way to communicate .Net Framework with Android (Java) but I have not found any example that uses it outside of a mobile application created in Visual Studio since in my case I would need to obtain objects and call functions from the .aar file

It seems like you are looking to use an AAR plugin, I haven't done it myself, but Unity has a doc on how to integrate it in your project.
Then, once that library is compiled in Android studio and integrated in Unity, you can look at this example on how to call it from C# code.
I haven't done it myself, but the example should put you on the right track.
Regarding the scripting backend, I don't believe it will have any impact on this.
Edit
Added Extract from the Example
Assets / Plugins / Android
Place your native android .AAR file inside this folder.
Now let’s write some code to call the plugin.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class NativeCodeRunner : MonoBehaviour
{
void Start(){
CallNativePlugin();
}
//method that calls our native plugin.
public void CallNativePlugin()
{
// Retrieve the UnityPlayer class.
AndroidJavaClass unityPlayerClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
// Retrieve the UnityPlayerActivity object ( a.k.a. the current context )
AndroidJavaObject unityActivity = unityPlayerClass.GetStatic<AndroidJavaObject>("currentActivity");
// Retrieve the "Bridge" from our native plugin.
// ! Notice we define the complete package name.
AndroidJavaObject alert = new AndroidJavaObject("plugins.vsoft.com.library.Alert");
// Setup the parameters we want to send to our native plugin.
object[] parameters = new object[2];
parameters[0] = unityActivity;
parameters[1] = "Hello World!";
// Call PrintString in bridge, with our parameters.
alert.Call("PrintString", parameters);
}
}

my main question is related to know how to get objects and call
functions from an .aar file in .NET Framework inside a dll C# file for
Unity
If you want to use AndroidJavaClass or AndroidJavaObject methods in your custom DLL, you should add references to the Unity DLLs. In Visual Studio, open the contextual menu for References in the Solution Explorer and select Add Reference. Then, select Browse > Select File.
At this stage, select the required .dll file, located in the UnityEngine folder.
using System;
/* Unity */
using UnityEngine;
namespace DLLTest {
public class MyDLLTest {
}
}

Nashorn access non-static Java method

In Java 7 (1.7), I could access a Java method from JavaScript by running this:
ScriptEngine jse = new ScriptEngineManager().getEngineByName("JavaScript");
jse.eval("importClass(net.apocalypselabs.symat.Functions);");
jse.eval("SyMAT_Functions = new net.apocalypselabs.symat.Functions();");
String input = "notify(\"Foo\");"; // This is user input
jse.eval("with(SyMAT_Functions){ "+input+" }");
Which would run the notify() function from the Functions java class:
public class Functions {
private Object someObjectThatCannotBeStatic;
public void notify(Object message) {
JOptionPane.showMessageDialog(null, message.toString());
}
/* Lots more functions in here, several working with the same non-static variable */
}
How do I access the Functions class in Java 1.8 with the Nashorn engine? My goal is to run different code for the first snippet if the user has Java 1.8, while still allowing people with 1.7 to use the app.
I've tried http://www.doublecloud.org/2014/04/java-8-new-features-nashorn-javascript-engine/ , https://docs.oracle.com/javase/8/docs/technotes/guides/scripting/nashorn/api.html , and How to instantiate a Java class in JavaScript using Nashorn? without luck. None of them seem to allow me the same thing as Java 1.7 did, instead assuming I only want to access static functions and objects.
The most common error I get:
I start with...
ScriptEngine jse = new ScriptEngineManager().getEngineByName("JavaScript");
jse.eval("var SyMAT_Functions;with (new JavaImporter(Packages.net.apocalypselabs.symat)) {"
+ "SyMAT_Functions = new Functions();}");
...then...
jse.eval("with(SyMAT_Functions){ "+input+" }");
...spits out...
TypeError: Cannot apply "with" to non script object in <eval> at line number 1

I was able to reproduce. First of all, Nashorn doesn't try to make it difficult to use Java objects (non-static or otherwise) in general. I have used it in other projects and not had any major issue converting from Rhino in Java 7 beyond what is covered in the migration guide. However, the issue here appears to deal with the use of the with statement which is "not recommended" and is even disallowed in strict mode of ECMAScript 5.1, both according to MDN.
Meanwhile, I found a thread on the Nashorn-dev mailing list discussing a similar case. The relevant part of the response was:
Nashorn allows only script objects (i.e., objects created by a JS
constructor or JS object literal expression) as scope expression for
"with" statement. Arbitrary objects . . . can not be used as 'scope' expression for
'with'.
In jdk9, support has been added to support script objects mirror other
script engines or other globals (which are instances of ScriptObjectMirror).
It's not the most elegant solution but, without using JDK 9, I was able to get your intended use of with to function by writing a proxy object inside the Javascript to mirror the public API of the Java class:
package com.example;
import javax.script.*;
public class StackOverflow27120811
{
public static void main(String... args) throws Exception {
ScriptEngine jse = new ScriptEngineManager().getEngineByName("JavaScript");
jse.eval(
"var real = new Packages.com.example.StackOverflow27120811(); " +
"var proxy = { doSomething: function(str) { return real.doSomething(str); } }; "
);
jse.eval("with (proxy) { doSomething(\"hello, world\"); } ");
}
public void doSomething(String foo) {
System.out.println(foo);
}
}
Attila Szegedi pointed out the non-standard Nashorn Object.bindProperties function. While it can't be expected to work with anything but the Nashorn engine, it does eliminate the complexity of re-declaring all of the public API inside the proxy object. Using this approach, the first jse.eval(...) call can be replaced by:
jse.eval(
"var real = new Packages.com.example.StackOverflow27120811(); " +
"var proxy = { }; " +
"Object.bindProperties(proxy, real); " // Nashorn-only feature
);

I decided to compile and bundle the "old" Rhino interpreter with my application instead of using Nashorn.
https://wiki.openjdk.java.net/display/Nashorn/Using+Rhino+JSR-223+engine+with+JDK8

JavaScript in Android

Is it possible to use JavaScript in Android?? if so, how? Please provide some examples.
Thanks.

I am way late to the party here, but I had this exact need. iOS 7 now includes JavaScriptCore
natively and it is really easy to use (despite limited documentation). The problem is that
I didn't want to use it unless I could also use something similar on Android. So I created the AndroidJSCore project. It allows you to use your JavaScript code natively in Android without requiring a bulky WebView and injection. You can also seamlessly make asynchronous
calls between Java and Javascript.
Update 27 Mar 17: AndroidJSCore has been deprecated in favor of LiquidCore. LiquidCore is based on V8 rather than JavascriptCore, but works essentially same. See the documentation on using LiquidCore as a raw Javascript engine.
From the documentation:
... to get started, you need to create a JavaScript JSContext. The execution of JS code
occurs within this context, and separate contexts are isolated virtual machines which
do not interact with each other.
JSContext context = new JSContext();
This context is itself a JavaScript object. And as such, you can get and set its properties.
Since this is the global JavaScript object, these properties will be in the top-level
context for all subsequent code in the environment.
context.property("a", 5);
JSValue aValue = context.property("a");
double a = aValue.toNumber();
DecimalFormat df = new DecimalFormat(".#");
System.out.println(df.format(a)); // 5.0
You can also run JavaScript code in the context:
context.evaluateScript("a = 10");
JSValue newAValue = context.property("a");
System.out.println(df.format(newAValue.toNumber())); // 10.0
String script =
"function factorial(x) { var f = 1; for(; x > 1; x--) f *= x; return f; }\n" +
"var fact_a = factorial(a);\n";
context.evaluateScript(script);
JSValue fact_a = context.property("fact_a");
System.out.println(df.format(fact_a.toNumber())); // 3628800.0
You can also write functions in Java, but expose them to JavaScript:
JSFunction factorial = new JSFunction(context,"factorial") {
public Integer factorial(Integer x) {
int factorial = 1;
for (; x > 1; x--) {
factorial *= x;
}
return factorial;
}
};
This creates a JavaScript function that will call the Java method factorial when
called from JavaScript. It can then be passed to the JavaScript VM:
context.property("factorial", factorial);
context.evaluateScript("var f = factorial(10);")
JSValue f = context.property("f");
System.out.println(df.format(f.toNumber())); // 3628800.0

Do you mean something like making a native app using Javascript? I know there are tools like Titanium Mobile that let you make native apps using web tools/languages.
You could also make Web Apps. There are loads of resources and tutorials out there for that. Just search "Android Web App tutorial" or something similar.

Yes you can, just create a wrap up code that points to html page and includes your javascript and css.
There are different libraries that can help you with this:
http://www.phonegap.com/
http://www.sencha.com/products/touch/
http://jquerymobile.com/

Just posting this for posterity but React Native is a great solution in this space. You can write a complete app in JS using native views under the hood, or embed a JS component inside an existing Java app. https://reactnative.dev/

how to use java to get a js file and execute it and then get the result

How can I use java to get a js file located on a web server, then execute the function in the js file and get the result and use the result in java.
Can you guys give me some code snippet? Great thanks.

You can use the scripting engine built into Java:
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public static void main(String[] args) throws Exception {
ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine engine = mgr.getEngineByName("JavaScript");
Object result = engine.eval("my-java-script-code")
System.out.println("Result returned by Javascript is: " + result);
}
Here is a more elaborate example.

There's three steps to this process:
Fetch the JS file from the server.
Execute some JS function from the file.
Extract the result.
The first step is fairly simple, there are lots of HTTP libraries in Java that will do this - you effectively want to emulate the simple functionality of something like wget or curl. The exact manner in which you do this will vary depending on what format you want the JS file in for the next step, but the process to get hold of the byte stream is straightforward.
The second step will require executing the JS in a Javascript engine. Java itself cannot interpret Javascript, so you'd need to obtain an engine to run it in - Rhino is a common choice for this. Since you'd need to run this outside of Java, you'll likely have to spawn a process for execution in Rhino using ProcessBuilder. Additionally, depending on the format of the Javascript you might need to create your own "wrapper" javascript that functions like a main class in Java and calls the method in question.
Finally you need to get the result out - obviously you don't have direct access to JavaScript objects from your Java program. The easiest way is going to be for the JS program to print the result to standard out (possibly serialising as something like JSON depending on the complexity of the object), which is being streamed directly to your Java app due to the way you launched the Rhino process. This could be another job for your JS wrapper script, if any. Otherwise, if the JS function has observable side effects (creates a file/modifies a database) then you'll be able to query those directly from Java.
Job done.
I hope you realise this question is far too vague to get full answers. Asking the public to design an entire system goes beyond the point where you'll get useful, actionable responses.

There are plenty of examples on the web of how to download a file from a URL.
Suns version of the JDK and JRE includes the Mozilla Rhino scripting engine.
Assuming you have stored the contents of the javascript file in a string called 'script', you can execute scripts as follows
String result = null;
ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine jsEngine = mgr.getEngineByName("JavaScript");
try {
jsEngine.eval(script);
result = jsEngine.get("result")
} catch (ScriptException ex) {
ex.printStackTrace();
}
The result will be extracted from the engine and stored in the 'result' variable.
The is a tutorial on scripting in Java that might be useful.

How can I fill out an online form with Java?

My cell phone provider offers a limited number of free text messages on their website. I frequently use the service although I hate constantly having a tab open in my browser.
Does anyone know/point me in the right direction of how I could create a jar file/command line utility so I can fill out the appropriate forms on the site. I've always wanted to code up a project like this in Java, just in case anyone asks why I'm not using something else.
Kind Regards,
Lar

Try with Webdriver from Google or Selenium.

Sounds like you need a framework designed for doing functional testing. These act as browsers and can navigate web sites for testing and automation. You don't need the testing functionality, but it would still serve your needs.
Try HtmlUnit, or LiFT, which is a higher-level abstraction built on HtmlUnit.

Use Watij with the Eclipse IDE. When your done, compile as an .exe or run with a batch file.
Here is some sample code I wrote for filling in fields for a Google search, which can be adjusted for the web form you want to control :
package goog;
import junit.framework.TestCase;
import watij.runtime.ie.IE;
import static watij.finders.SymbolFactory.*;
public class GTestCases extends TestCase {
private static watij.runtime.ie.IE activeIE_m;
public static IE attachToIE(String url) throws Exception {
if (activeIE_m==null)
{
activeIE_m = new IE();
activeIE_m.start(url);
} else {
activeIE_m.goTo(url);
}
activeIE_m.bringToFront();
return (activeIE_m);
}
public static String getActiveUrl () throws Exception {
String currUrl = activeIE_m.url().toString();
return currUrl;
}
public void testGoogleLogin() throws Exception {
IE ie = attachToIE("http://google.com");
if ( ie.containsText("/Sign in/") ) {
ie.div(id,"guser").link(0).click();
if ( ie.containsText("Sign in with your") ||
ie.containsText("Sign in to iGoogle with your")) {
ie.textField(name,"Email").set("test#gmail.com");
ie.textField(name,"Passwd").set("test");
if ( ie.checkbox(name,"PersistentCookie").checked() ){
ie.checkbox(name,"PersistentCookie").click();
}
ie.button(name,"signIn").click();
}
}
System.out.println("Login finished.");
}
public void testGoogleSearch() throws Exception {
//IE ie = attachToIE( getActiveUrl() );
IE ie = attachToIE( "http://www.google.com/advanced_search?hl=en" );
ie.div(id,"opt-handle").click();
ie.textField(name,"as_q").set("Watij");
ie.selectList(name,"lr").select("English");
ie.button(value,"Advanced Search").click();
System.out.println("Search finished.");
}
public void testGoogleResult() throws Exception {
IE ie = attachToIE( getActiveUrl() );
ie.link(href,"http://groups.google.com/group/watij").click();
System.out.println("Followed link.");
}
}

It depends on how they are sending the form information.
If they are using a simple GET request, all you need to do is fill in the appropriate url parameters.
Otherwise you will need to post the form information to the target page.

You could use Watij, which provides a Java/COM interface onto Internet Explorer. Then write a small amount of Java code to navigate the form, insert values and submit.
Alternatively, if it's simple, then check out HttpClient, which is a simple Java HTTP client API.
Whatever you do, watch out that you don't contravene your terms of service (easy during testing - perhaps you should work against a mock interface initially?)

WebTest is yet another webapp testing framework that may be easier to use than the alternatives cited by others.

Check out the Apache Commons Net Package. There you can send a POSt request to a page. This is quite low level but may do what you want (if not you might check out the functional testing suites but it is probably not as easy to dig into).

As jjnguy says, you'll need to dissect the form to find out all the parameters.
With them you can form your own request using Apache's HTTP Client and fire it off.