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How to use NodeJS in Android using J2V8

Posted by: admin November 30, 2017 Leave a comment

Questions:

I have created code for android using J2V8 library for executing nodejs script in android mobile. but it gives me error when i run application.

Gradle dependencies

compile 'com.eclipsesource.j2v8:j2v8:[email protected]'

Code

...

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_console);
    runScript();
}

private void runScript() {
    NodeJS nodeJS = NodeJS.createNodeJS();

    try {
        File script = createTempScript("console.log(\"Hello NodeJS\")");

        nodeJS.exec(script);

        script.delete();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        nodeJS.release();
    }

}

private File createTempScript(String script) throws IOException {
    File file = File.createTempFile("temp",".js", getCacheDir());
    FileWriter fileWriter = new FileWriter(file);
    fileWriter.write(script);
    fileWriter.close();
    return file;
}

...

Error

java.lang.RuntimeException: Unable to start activity ComponentInfo{in.asissuthar.lion/in.asissuthar.lion.ConsoleActivity}: java.lang.UnsupportedOperationException:
StartNodeJS Not Supported.
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2348)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2410)
        at android.app.ActivityThread.access$800(ActivityThread.java:151)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1313)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5345)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:947)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:742)

Please Help me to solve this error.


Normal V8 engine works fine but above createNodeJS gives error.

V8 v8 = V8.createV8Runtime()
Answers:

Root Cause

The J2V8 library contains a JAR and a native library containing v8 engine. In your case, the JNI native library is not compiled with -D NODE_COMPATIBLE=1 option and hence you get the following error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{in.asissuthar.lion/in.asissuthar.lion.ConsoleActivity}: java.lang.UnsupportedOperationException: StartNodeJS Not Supported.

This can be asserted by looking into J2V8 code. I have added below a snippet:

#ifndef NODE_COMPATIBLE
  (env)->ThrowNew(unsupportedOperationExceptionCls, "StartNodeJS Not Supported.");
#endif

Possible Solutions:

  1. You need to recompile the JNI source code with -D NODE_COMPATIBLE=1 option. The source code is available at https://github.com/eclipsesource/J2V8

OR

  1. Raise a ticket on their github so that they can update the aar with updated native library with node support.