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

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

4 Remarkable Notes for JSF Apps Using HTML5

In the previous post , I've already shared with you how my team consults clients by using a HTML prototype. This post is about the used technologies for reusing the provided HTML template and communicating with backend. What is the issue when using HTML elements with Primefaces components? Primefaces is a great extension for developing JSF web apps. However, it is really frustrating in case we have to make it work with an existing HTML template. Why? - Primefaces has its own theme for styling. - Primefaces changes the HTML structure. Therefore, that would be a huge effort to use the Primefaces' components to replicate the elements of the HTML template; especially it is impossible for images drawing by " canvas " tag. That requires us to find a better approach. Since Java EE 7 (introducing JSF 2.2 included), it supports to use HTML5 elements . The idea is that JSF components don't effect the style and HTML structure, so we can easily reuse the provided HTM...
2 comments
Read more

Performance of a Data Structure

Why data structures matter The fact is that programs are all about processing data. Data structures are referred to how data is organized which affects the time of executing a program. How to measure the performance of a data structure In order to measure "how fast"/efficiency/performance of a data structure, we measure the performance of its operations. There are four basic operations including reading , searching , insertion , and deletion . A pure time consuming is not used for the measuring because it is not reliable depending on the hardware that it is run on. But instead, we use the term time complexity which refers to how many steps an operation takes. An example of how a single rule can affect efficiency Let's compare two data structures: Array and Set (with N elements). 1. Array - Reading : 1 step (because the computer has the ability to jump to any particular index in the array) - Searching : N steps (the worst case with linear search) - Inserti...
Post a Comment
Read more

My must-have apps for daily work

There is no doubt that cool apps can help us be more productive and enjoyable at work. For the time being, I really love the following apps which are used by me almost every day. 1. A personal Kanban In fact, a personal kanban is the most useful app for me. Why does it matter? It is not just a to-do list, but it keeps me motivated every day because it helps me be able to know what my "big picture" is. I usually set up my plans together with a path to reach them.  KanbanFlow  is my preferred tool. KanbanFlow 2. A terminal Needless to say, a terminal is a must-have app for every developer, especially the ones use macOS/Linux. Due to its importance, I love to decorate and enhance it to be super exciting with various tools such as  iTerm ,  oh-my- zsh , and  thefuck . ;) iTerm + oh-my-zsh 3. A documentation "ecosystem" As a developer, I can not remember all things that I have experimented a day. Moreover, a document is really useful for sharing an...
Post a Comment
Read more

Regex - Check a text without special characters but German, French

Special characters such as square brackets ([ ]) can cause an exception " java.util.regex.PatternSyntaxException " or something like this if we don't handle them correctly. I had met this issue. In my case, my customers want our application should allow some characters in German and French even not allow some special characters. The solution is that we limit the allowed characters by showing the validation message on GUI. For an instance, the message looks like the following: "This field can't contain any special characters; only letters, numbers, underscores (_), spaces and single quotes (') are allowed." I used Regular Expression to check it. For entering Germany and French, I actually don't have this type of keyboard, so I referred these sites: * German characters: http://german.typeit.org/ * French characters: http://french.typeit.org/ Here is my code: package vn.nvanhuong.practice; import java.util.regex.Matcher; import java.util...
Post a Comment
Read more