This example uses Gson and OkHttp to call the Google GEocoder, documented at https://developers.google.com/maps/documentation/geocoding/intro . Note that the docs strongly imply you need a key, but as of Sep 2017 you still don’t. :)

The AddressEncoder class exists to show the three primary ways to deal with exceptions in streams. Since the URLEncoder.encode method throws an UnsupportedEncodingException, which is a checked exception, the code must prepare for that in order to complie.

The three approaches are:

• An try/catch block is embedded in the Function argument to the map method, which is ugly, but works (getEncodedAddress_usingTryCatch).

• The encoding process is extracted to a separate method, which is then accessed using a method reference. This is much cleaner and easier to read (getEncodedAddress_usingExtractedMethod). The extracted method is encodeString.

• A wrapper method is added that takes a new functional interface, FunctionWithException. The wrapper method invokes the apply method, catches any Exception that occurs, and rethrows it as unchecked. The wrapper method returns a standard java.util.function.Function instance, so it can be used in a map method in a stream pipeline (getEncodedAddress_usingWrapper).

Note that the Google Geocoder may not (yet) take a key, but it is throttled by Google. The free version supports only 2500 request/day (generally not a problem) and only 50 request/sec (which often is, especially when running tests). Therefore, if you add your own address to the test class GeocoderServiceTest, be sure to stay within those limits.

This is an extended example based on a discussion of exception handling in streams in the book Modern Java Recipes (http://shop.oreilly.com/product/0636920056669.do), from O’Reilly Media. Please let me know if there are any problems. Better yet, feel free to fork the repo and send me a pull request if you find any errors.