At Data Geekery, we love Java. And as we’re really into jOOQ’s fluent API and query DSL, we’re absolutely thrilled about what Java 8 will bring to our ecosystem.
Java 8 Friday
Every Friday, we’re showing you a couple of nice new tutorial-style Java 8 features, which take advantage of lambda expressions, extension methods, and other great stuff. You’ll find the source code on GitHub.
For the last two Fridays, we’ve been off for our Easter break, but now we’re back with another fun article:
Let’s Deprecate Those Legacy Libs
Apart from Lambdas and extension methods, the JDK has also been enhanced with a lot of new library code, e.g. the Streams API and much more. This means that we can critically review our stacks and – to the great joy of Doctor Deprecator – throw out all the garbage that we no longer need.
Here are a couple of them, just to name a few:
LINQ-style libraries
There are lots of libraries that try to emulate LINQ (i.e. the LINQ-to-Collections part). Oracle Certified Streams Developer certifications hanging up our walls.
Don’t get me wrong. This isn’t about LINQ or Streams being better. They’re pretty much the same. But since we now have Streams in the JDK, why worry about LINQ? Besides, the SQLesque syntax for collection querying was misleading anyway. LambdaJ
This was a fun attempt at emulating closures in Java through arcane and nasty tricks like ThreadLocal. Consider the following code snippet (taken from here):
// This lets you "close over" the
// System.out.println method
Closure println = closure(); {
of(System.out).println(var(String.class));
}
// in order to use it like so:
println.apply("one");
println.each("one", "two", "three");Nice idea, although that semi-colon after closure(); and before that pseudo-closure-implementation block, which is not really a closure body… all of that seems quite quirky!
Now, we’ll write:
Consumer<String> println = System.out::println;
println.accept("one");
Stream.of("one", "two", "three").forEach(println);No magic here, just plain Java 8.
Let’s hear it one last time for Mario Fusco and Lambdaj.
Linq4j
Apparently, this is still being developed actively… Why? Do note that the roadmap also has a LINQ-to-SQL implementation in it, including:
Parser support. Either modify a Java parser (e.g. OpenJDK), or write a pre-processor. Generate Java code that includes expression trees.
Yes, we’d like to have such a parser for jOOQ as well. It would allow us to truly embed SQL in Java, similar to SQLJ, but typesafe. But if we have the Streams API, why not implement something like
We cannot say farewell to Julian Hyde‘s Linq4j just yet, as he’s still continuing work. But we believe that he’s investing in the wrong corner.
Coolection
This is a library with a fun name, and it allows for doing things like…
from(animals).where("name", eq("Lion"))
.and("age", eq(2))
.all();
from(animals).where("name", eq("Dog"))
.or("age", eq(5))
.all();But why do it this way, when you can write:
animals.stream()
.filter(a -> a.name.equals("Lion")
&& a.age == 2)
.collect(toList());
animals.stream()
.filter(a -> a.name.equals("Dog")
|| a.age == 5)
.collect(toList());Let’s hear it for Wagner Andrade. And then off to the bin
Half of Guava
Guava has been pretty much a dump for all sorts of logic that should have been in the JDK in the first place. Take com.google.guava.base.Joiner for instance. It is used for string-joining:
Joiner joiner = Joiner.on("; ").skipNulls();
. . .
return joiner.join("Harry", null, "Ron", "Hermione");No need, any more. We can now write:
Stream.of("Harry", null, "Ron", "Hermione")
.filter(s -> s != null)
.collect(joining("; "));Note also that the skipNulls flag and all sorts of other nice-to-have utilities are no longer necessary as the Streams API along with lambda expressions allows you to decouple the joining task from the filtering task very nicely.
Convinced? No?
What about:
com.google.common.base.Optional->java.util.Optionalcom.google.common.base.Predicate->java.util.function.Predicatecom.google.common.base.Supplier->java.util.function.Supplier
And then, there’s the whole set of Functional stuff that can be thrown to the bin as well:
https://code.google.com/p/guava-libraries/wiki/FunctionalExplained
Of course, once you’ve settled on using Guava throughout your application, you won’t remove its usage quickly. But on the other hand, let’s hope that parts of Guava will be deprecated soon, in favour of an integration with Java 8.
JodaTime
Now, this one is a no-brainer, as the popular JodaTime library got standardised into the java.time packages. This is great news.
Let’s hear it for “Joda” Stephen Colebourne and his great work for the JSR-310.
Apache commons-io
The java.nio packages got even better with new methods that nicely integrate with the Streams API (or not). One of the main reasons why anyone would have ever used Apache Commons IO was the fact that it is horribly tedious to read files prior to Java 7 / 8. I mean, who would’ve enjoyed this piece of code (from here):
try (RandomAccessFile file =
new RandomAccessFile(filePath, "r")) {
byte[] bytes = new byte[size];
file.read(bytes);
return new String(bytes); // encoding?? ouch!
}Over this one?
List<String> lines = FileUtils.readLines(file);
But forget the latter. You can now use the new methods in java.nio.file.Files, e.g.
List<String> lines = Files.readAllLines(path);
No need for third-party libraries any longer!
Serialisation
Throw it all out, for there is JEP 154 deprecating serialisation. Well, it wasn’t accepted, but we could’ve surely removed about 10% of our legacy codebase.
A variety of concurrency APIs and helpers
With JEP 155, there had been a variety of improvements to concurrent APIs, e.g. to ConcurrentHashMaps (we’ve blogged about it before), but also the awesome LongAdders, about which you can read a nice article over at the Takipi blog.
Haven’t I seen a whole com.google.common.util.concurrent package over at Guava, recently? Probably not needed anymore.
JEP 154 (Serialisation) wasn’t real
It was an April Fools’ joke, of course…
Base64 encoders
How could this take so long?? In 2003, we’ve had RFC 3548, specifying Base16, Base32, and Base64 data encodings, which was in fact based upon base 64 encoding specified in RFC 1521, from 1993, or RFC 2045 from 1996, and if we’re willing to dig further into the past, I’m sure we’ll find earlier references to this simple idea of encoding binary data in text form.
Now, in 2014, we finally have JEP 135 as a part of the JavaSE8, and thus (you wouldn’t believe it): java.util.Base64.
Off to the trash can with all of these libraries!
- Apache Commons Codec (unless you’re using some other weird encoding from that library
- JAXB’s internal Base64 encoders
- Gauva, again
- JEE’s
javax.mail.internet.MimeUtility - Jetty’s implementation
- This weird thing here
- Or this weird thing here
… gee, it seems like everyone and their dog worked around this limitation, prior to the JDK 8…
More?
Provide your suggestions in the comments! We’re curious to hear your thoughts (with examples!)
Conclusion
As any Java major release, there is a lot of new stuff that we have to learn, and that allows us to remove third-party libraries. This is great, because many good concepts have been consolidated into the JDK, available on every JVM without external dependencies.
Disclaimer: Not everything in this article was meant seriously. Many people have created great pieces of work in the past. They have been very useful, even if they are somewhat deprecated now. Keep innovating, guys!
Want to delve more into the many new things Java 8 offers? Go have a look over at the Baeldung blog, where this excellent list of Java 8 resources is featured:
… and stay tuned for our next Java 8 Friday blog post, next week!
| Reference: | Java 8 Friday: Let’s Deprecate Those Legacy Libs from our JCG partner Lukas Eder at the JAVA, SQL, AND JOOQ blog. |
