javagraalvmgraaljs

Add binding to static class Math in graal context

I use e.g.

context.getBindings("js").putMember("thing", new Thing(this));

to define a variable for my javascript.

How can I expose Java's Math """"object""""?

I can't do

context.getBindings("js").putMember("math", Math);

nor

context.getBindings("js").putMember("math", new Math());

(bc the constructor is private)

Solution

  • Even using reflection like this to pass it

    Constructor[] cs = Math.class.getDeclaredConstructors();
cs[0].setAccessible(true);
Math m = (Math) cs[0].newInstance();
context.getBindings("js").putMember("math", m);

    Doesn't work in the end, because graaljs doesn't make static properties of Java host objects visible to the JavaScript.

    So the solution is to use the .static property of Math.class

    context.getBindings("js").putMember("math", Math.class);
System.out.println(context.eval("js", "math.static.toRadians(180)")); // prints 3.141592653589793

    As I learnt here