Skip to main content

Small Changes to Java 7 via Project Coin and Why They are Useful


Did you know how new features were added into Java 7? The following are functionalities that can be considered.
Source: [1]
Project Coin is all about the changes in the range from syntactic sugar to new language feature. This is what we're talking about today.

Since Java 7 is the first version developed in an open source manner, there is an amount of actions that must be performed for any changes as follows:
  • Update the Java Language Specification (JSL)
  • Implement a prototype in the source compiler
  • Add library support essential for the change
  • Write tests and examples
  • Update document
  • Etc, ...
Project Coin has submitted a lot of proposals (almost 70) but only some of them are chosen to Java 7. Why? Briefly, Java is a rich static type system and it has a lot of possible interaction points between different bits of it. Making changes to this type system is prone to creating unexpected surprises.

Wow! It is tough, right? Let's take a look what features Project Coin brought to Java 7.

Strings in switch statement

Question: Why do we need "switch"? (already supported by prior Java 7)
Answer: To avoid lots of ugly nested "ifs".
Question: Why do we need "string" in "switch"?
Answer: Just to make life in Java 7 a little bit easier. Agree?

Enhanced syntax for numeric literals

Underscores in numbers to improve readability.
E.g: 100_000_000 and 10_000_000 are much more readable than 100000000 and 10000000.

Improved exception handling

- Multicatch: it groups a family of exceptions into one catch statement; this feature can reduce code duplication.
- Final rethrow: it won't force to declare the exception signature. For example, my IDE complains of the block below with Java 6 compiler, but Java 7.

However, the issue here is the real dynamic type of the exception has been swallowed if we declare the exception signature.
And, the change in Java 7 is just simple as follows: 

try {
  doSomethingWhichMightThrowIOException();
  doSomethingElseWhichMightThrowSQLException();
} catch (final Exception e) {
  //...
  throw e;
}

Why is final keyword useful? Because it provides a new semantics of catch and rethrow. The appearance of the final keyword indicates that the type that’s actually thrown is the runtime type of the exception that was encountered.

Note: If a catch block handles more than one exception type, then the catch parameter is implicitly final.

Try-with-resources

#Funfact: Virtually no one gets manual resource closing 100 percent right.
Therefore, using try-with-resources to eliminate unnecessary bugs from your codebase.

try(OutputStream out = new FileOutputStream(file);
InputStream is = url.openStream()){
 byte[] buf = new byte[4096];
 int len;
 while ((len = is.read(buf)) > 0) {
  out.write(buf, 0, len);
 }
}

Diamond syntax

To avoid the definition and setup of instances can be really verbose.
#Funfact: Why "diamond syntax" name? Because original name, ITIGIC (Improved Type Inference for Generic Instance Creation), is a very long(stupid) name and the shortened type information looks like a diamond.

Simplified varagrs method invocation

What is it? It just moves a warning about type information for a very specific case where varargs combines with generics in a method signature.

An admitted weaknesses of Java’s generics—you aren’t normally allowed to create an array of a known generic type. For example, this won't compile:

HashMap<String, String>[] arrayHm = new HashMap<>[2];

So when it runs into this circumstance, the compiler cheats and breaks its own rule about the forbidden array of generic type. It throws the warning "unchecked" which is darkly meaning. Oops! Then, dummy developers want to know why their methods are "unchecked"? They need an explanation.

To make things easier for developers and by annotating the method with "@SafeVarargs", the developer essentially asserts that method doesn't perform any unsafe operations. Known issue! ;)

Reference:



[1]. Benjamin J. Evans and Martijn Verburg, “The Well-Grounded Java Developer: Vital techniques of Java 7 and polyglot programming"

Labels:

Comments

Post a Comment

Popular posts from this blog

[Snippet] CSS - Child element overlap parent

I searched from somewhere and found that a lot of people says a basic concept for implementing this feature looks like below: HTML code: <div id="parent">  <div id="child">  </div> </div> And, CSS: #parent{   position: relative;   overflow:hidden; } #child{   position: absolute;   top: -1;   right: -1px; } However, I had a lot of grand-parents in my case and the above code didn't work. Therefore, I needed an alternative. I presumed that my app uses Boostrap and AngularJs, maybe some CSS from them affects mine. I didn't know exactly the problem, but I believed when all CSS is loaded into my browser, I could completely handle it. www.tom-collinson.com I tried to create an example to investigated this problem by Fiddle . Accidentally, I just changed: position: parent; to position: static; for one of parents -> the problem is solved. Look at my code: <div class="modal-body dn-placeholder-parent-positi...
Post a Comment
Read more

Today I Learned - Git at First Glance

Getting Started It's always fun to jump right in to the "HelloWorld" app. Just go for it! Visit: https://try.github.io/levels/1/challenges/1 Cheatsheet It's time for us to store our "magic tools". Visit:  https://www.git-tower.com/blog/git-cheat-sheet Which collaboration way fit your team? Git is just a tool which doesn't teach you how to work properly in a team. It depends on your projects and you need to choose your own team workflow. Visit: https://www.atlassian.com/git/tutorials/comparing-workflows
Post a Comment
Read more

Selenium - Override javascript functions to ignore downloading process

I have got an issue with downloading process on IE 8. This browser blocks my automatic-download functionality on my app so that I could not work with my test case any more after that. In my case, I didn't care about the file is downloaded or not, I just focus on the result after downloading process finished successfully. Therefore, I found a solution to ignore this process so that I can work normally. I use Primefaces, here is the remote command to trigger the download process <p:remoteCommand name="cmdGenerateDocument" actionListener="#{logic.onGenerateDocument}" update="xrflDocumentCreationPanel" oncomplete="clickDownloadButton();"/> The following is my test case: @Test public void shouldUpdateStep6ToWarningIfStep1IsValidAfterFinished(){ MainPage mainPage = new MainPage(); waitForLoading(mainPage.getDriver()); EmployeeDetailPage empDetailPage = new EmployeeDetailPage(); waitForLoading(empDetailPage.getDriver()); e...
Post a Comment
Read more

Creating a Chatbot with RiveScript in Java

Motivation "Artificial Intelligence (AI) is considered a major innovation that could disrupt many things. Some people even compare it to the Internet. A large investor firm predicted that some AI startups could become the next Apple, Google or Amazon within five years"   - Prof. John Vu, Carnegie Mellon University. Using chatbots to support our daily tasks is super useful and interesting. In fact, "Jenkins CI, Jira Cloud, and Bitbucket" have been becoming must-have apps in Slack of my team these days. There are some existing approaches for chatbots including pattern matching, algorithms, and neutral networks. RiveScript is a scripting language using "pattern matching" as a simple and powerful approach for building up a Chabot. Architecture Actually, it was flexible to choose a programming language for the used Rivescript interpreter like Java, Go, Javascript, Python, and Perl. I went with Java. Used Technologies and Tools Oracle JDK 1.8...
Post a Comment
Read more

BarcampSaigon 2015

Barcamp Saigon is one of my most expected events of the year. This year, it took place at RMIT university. As usual, it brought many useful topics to the community. Here is all topics that I have attended. Scale it! - Lars Jankowfsky Lars is founder of 8bitrockr.com How do we make a decision correctly? It is hard to know that until we try and measure it. He gave an example about how good an app was. And, most of people thought that the app with nice user interfaces is good at the first look. But it is not correct because it is only true until we try to use it, even the nice GUI app sometime is not good at UX, functionalities, etc. The key of success for working in team is collaboration. We can not only base on the experience of members likes: "In my opinions| As I know.... this is the best way..bla..bla.." but we should test it. Therefore, manually testing as well as automation testing is more and more necessary nowadays. "Don't think, just try...
2 comments
Read more