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

DevOps for Dummies

Everyone talks about it, but not everyone knows what it is. Why DevOps? In general, whenever an organization adopts any new technology, methodology, or approach, that adoption has to be driven by a business need. Any kind of system that need rapid delivery of innovation requires DevOps (development and operations). Why? DevOps requires mechanisms to get fast feedback from all the stakeholders in the software application that's being delivered. DevOps approaches to reduce waste and rework and to shift resources to higher-value activities. DevOps aims to deliver value (of organization or project) faster and more efficiently. DevOps Capabilities The capabilities that make up DevOps are a broad set that span the software delivery life cycle. The following picture is a reference architecture which provides a template of a proven solution by using a set of preferred methods and capabilities. My Remarks Okay, that sounds cool. What does it simply mean, again? The f...
Post a Comment
Read more

AngularJS - Build a custom validation directive for using multiple emails in textarea

AngularJS already supports the built-in validation with text input with type email. Something simple likes the following: <input name="input" ng-model="email.text" required="" type="email" /> <span class="error" ng-show="myForm.input.$error.email"> Not valid email!</span> However, I used a text area and I wanted to enter some email addresses that's saparated by a comma (,). I had a short research and it looked like AngualarJS has not supported this functionality so far. Therefore, I needed to build a custom directive that I could add my own validation functions. My validation was done only on client side, so I used the $validators object. Note that, there is the $asyncValidators object which handles asynchronous validation, such as making an $http request to the backend. This is just my implementation on my project. In order to understand that, I supposed you already had experiences with ...
Post a Comment
Read more

Junit - Test fails on French or German string assertion

In my previous post about building a regex to check a text without special characters but allow German and French . I met a problem that the unit test works fine on my machine using Eclipse, but it was fail when running on Jenkins' build job. Here is my test: @Test public void shouldAllowFrenchAndGermanCharacters(){ String source = "ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ"; assertFalse(SpecialCharactersUtils.isExistSpecialCharater(source)); } Production code: public static boolean isExistNotAllowedCharacters(String source){ Pattern regex = Pattern.compile("^[a-zA-Z_0-9_ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ]*$"); Matcher matcher = regex.matcher(source); return !matcher.matches(); } The result likes the following: Failed tests: SpecialCharactersUtilsTest.shouldAllowFrenchAndGermanCharacters:32 null A guy from stackoverflow.com says: "This is probably due to the default encoding used for your Java source files. The ö in the string literal in the J...
5 comments
Read more

What the heck is Meteor DDP?

I was using Meteor for my messenger project. I was so curious about the real time connection. I wanted to know how exactly this mechanism works. In this post, I will go through the DDP Specification, an overview of WebSocket, and a simple demo about how to subscribe a publication of Rocket.Chat (containing a DDP server) from an external webpage. At a glance, I knew that Meteor invented a protocol called DDP which uses for handling real time connection. So then, what is DDP? "DDP (Distributed Data Protocol) is the stateful WebSocket protocol that Meteor uses to communicate between the client and the server." [1] All right! Why does DDP matter? "DDP is a standard way to solve the biggest problem facing client-side JavaScript developers: querying a server-side database, sending the results down to the client, and then pushing changes to the client whenever anything changes in the database" . [2] In order to understand deeply the protocol, I decided ...
Post a Comment
Read more

Strategy Design Pattern

For example, I have a program with an Animal abstract class and two sub-classes Dog and Bird. I want to add new behavior for the class Animal, this is "fly".  Now, I face two approaches to solve this issue: 1. Adding an abstract method "fly" into the class Animal. Then, I force the sub-classes should be implemented this method, something like: public abstract class Animal{ //bla bla public abstract void fly(); } public class Bird extends Animal{ //bla bla public void fly(){ System.out.println("Fly high"); } } public class Dog extends Animal{ //bla bla public void fly(){ System.out.println("Cant fly"); } } 2. Creating an interface with method "fly" inside. The same issue to an abstract class, I force the classes these implement this interface should have a method "fly" inside: public interface Flyable{ public void fly(); } public class Bird implements Flyable{ //bla bla public void fly(){ System.out.pr...
Post a Comment
Read more