Joe, would you consider adding support for Promises/A+ (i.e. merging a PR if I prepared one)? Currently node-java creates two javascript methods for every method of a class, an async version with the same name, and a sync version with the 'Sync' suffix. We'd like to have a third variant, which is async but returning a promise. We have used both Q and Bluebird. I believe it is possible to implement a solution that would let users of node-java choose which promises library they would use, by simply adding to the node-java API the ability to pass in a 'promisify' function.

Something along the lines of:

var java = require('java');
var asyncOptions = {
  promisify: require('q').nfbind     // or require('bluebird').promisify
  suffix: 'Promise'
};
java.setAsyncOptions(asyncOptions);
java.classpath.push(...);
...

I use 'asyncOptions' instead of 'promisesOptions' since I imagine the possibility of disabling the generation of callback-style async methods, and only using promises.

I've started inspecting the current node-java sources to figure out how to implement the change. There are some easy changes that can be made in lib/nodeJavaBridge.js, and perhaps that is the right place to promisify static methods, with code along these lines:

// copy static methods
var methods = clazz.getDeclaredMethodsSync();
for (i = 0; i < methods.length; i++) {
  if (((methods[i].getModifiersSync() & MODIFIER_PUBLIC) === MODIFIER_PUBLIC)
    && ((methods[i].getModifiersSync() & MODIFIER_STATIC) === MODIFIER_STATIC)) {
    var methodName = methods[i].getNameSync();
    result[methodName + 'Sync'] = java.callStaticMethodSync.bind(java, name, methodName);
    result[methodName] = java.callStaticMethod.bind(java, name, methodName);
    result[methodName + asyncOptions.suffix ] = asyncOptions.promisify(result[methodName]);   // Add just this one line
  }
}

Promisifying instance methods is harder. It requires knowledge of v8 and nan that I don't yet have. I see that maybe the key changes would be localized to a few lines in javaObject.cpp, in the loop across instance methods around lines 45 to 56. I can probably figure it out with more study of the documentation for v8 and nan, but I wonder if you might be able to help me out with that part?