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

Gzip upload on browsers

Today, I faced a problem that I could not upload my archive file with gzip format on Firefox, even it worked on Chrome. I was using macOS. My application had a setting to whitelist accepted files. I’ve already added "application/gzip" to that list. "It’s strange!", I thought. I finally figured out that my uploaded file's type actually was "application/x-gzip" on Firefox. I also asked my colleagues to check their uploaded files on Window and Ubuntu. Hmm… they were totally different! It was "application/x-compressed" on Window, and was "application/x-compressed-tar" on Ubuntu. In fact, gzip is already standardized by IANA. There is a note in RFC-6713 as below: "Some applications have informally used media types such as application/gzip-compressed, application/gzipped, application/x-gunzip, application/x-gzip, application/x-gzip-compressed, and gzip/document to describe data compressed with gzip. The media types defin...
2 comments
Read more

DevOps Toolchain Enhancement

 Historically, our company ubitec had started with a customer project. Agile/Scrum was our proposal for working with customers. Time by time, Agile/Scrum also became our culture for software development. To be successful with this development approach, we somehow needed to have a fast release for customers (i.e. every one week). Back then, we had a build tool Jenkins which was responsible for having sprint release packages for our customers. The build job pipelines contain some steps such as gathering the artifacts, checking the code convention, running the tests, building docker images, and packaging an archived file (a zip file). The set of tools involved in a pipeline is roughly called a toolchain. It is just a part of a bigger process called the DevOps toolchain. Source: https://www.ibm.com/blogs/cloud-archive/2016/11/devops-architecture-available-on-bluemix-garage-method-site/ DevOps is a proven method that fits Agile. Today,  it is even treated as a mandatory factor...
Post a Comment
Read more

The HelloWorld example of JSF 2.2 with Myfaces

I just did by myself create a very simple app "HelloWorld" of JSF 2.2 with a concrete implementation Myfaces that we can use it later on for our further JSF trying out. I attached the source code link at the end part. Just follow these steps below: 1. Create a Maven project in Eclipse (Kepler) with a simple Java web application archetype "maven-archetype-webapp". Maven should be the best choice for managing the dependencies , so far. JSF is a web framework that is the reason why I chose the mentioned archetype for my example. 2. Import dependencies for JSF implementation - Myfaces (v2.2.10) into file pom.xml . The following code that is easy to find from  http://mvnrepository.com/  with key words "myfaces". <dependency> <groupId>org.apache.myfaces.core</groupId> <artifactId>myfaces-api</artifactId> <version>2.2.10</version> </dependency> <dependency> <groupId>org.apache.myfaces.core<...
Post a Comment
Read more

BIRT - Fix the size of an image

I use a dynamic image as a logo my report in pdf. At the beginning, I use table to align the logo in left or right. I meet a problem with some images with a large width or height. My customer requires that the logo should be displayed in original size. These following steps solves my problem: 1. Use Grid instead of Table 2. Set Grid "Height" is 100%  and "Width" is blank 3. Set "Fit to container" for images are "true". Download the the template here .
Post a Comment
Read more

Just another career path

As a software engineer, I recently have heard of a lot of feedback from my colleagues and friends that they don’t see their career path or they don’t know how to move to the new levels in their company. No exception, I used to have that thinking before.  In my opinion, there is a very important reason why people are struggling to find the answer because “career path is not always the job titles”. Normally, each company has its own job titles such as junior-level developer, middle-level developer, senior-level developer, teach lead, software architect, CTO, etc. Hence, it is not true that a job title is reasonable for every company. The interview is often conducted hardly to find a candidate matching the company title. If we have a good enough job title standard, the interview would take place very easily, right? Therefore, I prefer to define my own career path through what skills are gained under a job title. But wait, why do I need a career path? To me, a career is an indispensabl...
Post a Comment
Read more