Tuesday, July 12, 2011

Java SE 7

JDK 1.0 was released on the 23rd January 1996. Then came:
  • JDK 1.1 (Feb 1997)
  • J2SE 1.2 (Dec '98)
  • J2SE 1.3 (May '00)
  • J2SE 1.4 (Feb '02)
  • J2SE 5.0 (sept 04)
  • Java SE 6 (Dec '06)
Each of these major releases has had minor releases which dealt with less important things (such as fixing bugs!) and after the 26th update for Java SE 6, it's now finally time for Java SE 7 to be released - officially.  Codenamed Dolphin Java SE 7 has had several preview releases, the 28th of July is the day the binaries get an official release. Incidently, not too many household names have their birthday day on the 28th July (unless you're familiar with Greek singer Nacy Alexiadi, American actor Tom Pelphrey or English Soccer player Michael Carrick) so perhaps the 28th is now a good reason to light a candle on the day which also saw Austria-Hungary declare war on Serbia (thank you Google, Wikipedia...). Having worked on every major release of Java except 1.0, I have to say I'm excited about Java SE 7.0.  Especially since no language changes (i.e. programming constructs) were introduced in Java SE 6 (even though some cool ones were introduced in Java SE 5 such as generics, autoboxing, varargs...)

Language changes is the area that I find most interesting because it is what developers will get to use in their day to day jobs. It's what people will notice. It's what people will talk about. Now, in Java SE 7 the language development was under a sub-project known as Project Coin.  There was an open call for proposals between Feb 27th, 2009 and March 30, 2009 and in total 70 proposals received some extensive discussion. The 70 were then narrowed down to five or so and now we're going to take a look at the ones that are part of Java SE 7.

Binary Literals In Java SE 7, the integral types (byte, short, int, and long) can also be expressed using the binary number system. To specify a binary literal, add the prefix 0b or 0B to the number. Type - inference for Generics JDK 1.5 saw the introduction of generics. One of the great advantages of generics was cleaner code because the need for casting was eliminated (if the generics feature was used correctly!).  However, unless you enjoyed those annoying compile time warnings about type safety you had to generify both the declaration and instantiation. For example, suppose you had a list of tennis balls... The annoying thing about having to do this is that it re-introduced code bloat - something generics was trying to reduce.  Now in Java SE 7 there is type inference for generic instance creation.  You can substitute the parameterized type of the constructor with an empty set of type parameters <> (also known as the diamond operator).  That means you can do: and you won't get any annoying warning but you'll still get all the benefits of compile time type safety provided by generics.

Catching multiple exceptions I really like this one.  Say you're catching multiple exceptions where some of the exceptions don't form an inheritance hierarchy but share the same exception handling code. You're going to end up with code bloat. For example: With Java SE 7, you can now do: Not bad eh - bound to tidy up tonnes of code. In addition to the ability to catch mulitple exceptions there is also some new precision available regarding re-throwing of exceptions.  

Underscores in literals Underscores can be used in literals now to make them more easier to read:

Strings can be used in Switch statements Switch statements are useful. They can be used with primitive types and enumerated types. In Java SE 7, they can also be used with Strings. Note: this simple but useful feature was officially suggested from the lead engineer of Project Coin, Joseph D. Darcy.  You can check out his blog here.

Autoclosing of resources (also known as try-with-resources) This is a classic programming error. You use a resource (e.g. a JDBC connection) and you forget to close it.  Now, once the resource implements java.io.AutoClosable (or the interface java.io.Closeable) you don't need to close it. Yippee. The list of classes in the JDK that implement this in the JDK is pretty extensive.  Just check the JDoc. for the AutoCloseable interface. Interestingly this proposal came from Joshua Bloch, the acclaimed author of the stupendous Effective Java - a must read for all serious programmers. Note in addition to the new progamming features, Java SE 7 also includes:

  • Increased support for dynamic languages (such as Ruby and Python)
  • Improved security support. Eliptic-curve crytography (ECC) implementation will be included.
  • Improved class loader support
  • and much more

Check it out...

References

  1. Binary literals and underscores in literals http://blogs.oracle.com/darcy/entry/project_coin_literal_grammar_hackery
  2. Strings in switch http://blogs.oracle.com/darcy/entry/project_coin_string_switch_anatomy
  3. Diamond operator http://mail.openjdk.java.net/pipermail/coin-dev/2009-November/002393.html and  http://download.java.net/jdk7/docs/technotes/guides/language/type-inference-generic-instance-creation.html
  4. Improved exception handling http://blogs.oracle.com/darcy/entry/project_coin_multi_catch_rethrow
  5. Simplified varargs method invocation http://blogs.oracle.com/darcy/entry/projectcoin_inducing_contributory_pollution
  6. Try-with-resources http://blogs.oracle.com/darcy/entry/project_coin_try_out_try
  7. Java Programming Language Feature enhancements http://download.java.net/jdk7/docs/technotes/guides/language/enhancements.html
  8. Improved Compiler Warnings and Errors When Using Non-Reifiable Formal Parameters with Varargs Methods http://download.java.net/jdk7/docs/technotes/guides/language/non-reifiable-varargs.html

4 comments:

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