Question

For example suppose I have

abstract class OrderRouter extends Market {
}

I would normally instantiate as follows

new OrderRouter with NYSE

How would I translate the above line into java? NYSE is a trait which extends Market.

Answer 1

Have a look at the question How are Scala traits compiled into Java bytecode?, and the accepted answer.

The summary is that, assuming NYSE has a getOrderBook() method, the Java version would look like:

new OrderRouter() {
    public OrderBook getOrderBook() {
        return NYSE$class.getOrderBook();
    }
}

The Scala compiler generates bytecode for synthetic classes, which mix in all of the trait implementations via composition/wrapping. Since javac doesn’t have this feature, you need to wire in the delegation of trait methods to the trait’s singleton object yourself.