New Java 7 Language Features

Last week I was at the Java 7 launch party in Sao Paulo, Brazil and it was really cool. There were a lot of developers on the party to celebrate Java 7 (afterall, we have been waiting for it for 5 years!).

I took some pictures at the event: http://www.flickr.com/photos/loiane/sets/72157627015952961/

Video of the event: http://blogs.oracle.com/java/entry/java_7_celebration_begins

Slides: http://blogs.oracle.com/darcy/resource/ProjectCoin/CoinLaunch.pdf

Anyways, I was really excited with the event and I went home and started to play with Java 7 language features.

As I will have to wait for Open JDK for Mac to be released, I had to play with it on Windows. You can download Java 7 here.

Another issue I found is Eclipse does not have native support for Java 7. They released a plugin, but it still beta. So I decided to play with NetBeans.

The current version of NetBeans is 7, and it already comes with native support to Java 7. If you install Java 7 and then install NetBeans, it will set Java 7 as the default JDK for development.

Then I created a Java Project on NetBeans but the source code was still compiling in Java 6. You have to make a small change to make it compile with Java 7.

All set and I started to play with some languages new features, aka Project Coin.

Strings in Switch:

In all examples, I tried first to write code as we usually do, and then convert the code to a Java 7 feature. The cool thing about NetBeans is it already have tips to convert the code.

First, will compare some Strings using if-else. NetBeans will popup a warning like this:

And if we accept the change, it will convert the code into this:

Following is the code:

Before:

 public void testStringInSwitch(String param){

        final String JAVA5 = "Java 5";
        final String JAVA6 = "Java 6";
        final String JAVA7 = "Java 7";

        if (param.equals(JAVA5)){
            System.out.println(JAVA5);
        } else if (param.equals(JAVA6)){
            System.out.println(JAVA6);
        } else if (param.equals(JAVA7)){
            System.out.println(JAVA7);
        }
    }

Java7:

 public void testStringInSwitch(String param){

        final String JAVA5 = "Java 5";
        final String JAVA6 = "Java 6";
        final String JAVA7 = "Java 7";

        switch (param) {
            case JAVA5:
                System.out.println(JAVA5);
                break;
            case JAVA6:
                System.out.println(JAVA6);
                break;
            case JAVA7:
                System.out.println(JAVA7);
                break;
        }
    }

Binary Literals:

Before:

public void testBinaryIntegralLiterals(){

        int binary = 8;

        if (binary == 8){
            System.out.println(true);
        } else{
            System.out.println(false);
        }
}

Java7:

 public void testBinaryIntegralLiterals(){

        int binary = 0b1000; //2^3 = 8

        if (binary == 8){
            System.out.println(true);
        } else{
            System.out.println(false);
        }
}

And if you try to declare a constant number in the code, NetBeans will warn you to convert it into a Binary Literal:

to

public void testUnderscoresNumericLiterals() {

        int oneMillion_ = 1_000_000;
        int oneMillion = 1000000;

        if (oneMillion_ == oneMillion){
            System.out.println(true);
        } else{
            System.out.println(false);
        }
    }

Underscore Between Literals:

public void testUnderscoresNumericLiterals() {

	int oneMillion_ = 1_000_000; //new
    int oneMillion = 1000000;

    if (oneMillion_ == oneMillion){
		System.out.println(true);
    } else{
        System.out.println(false);
    }
}

Diamond Syntax:

Before:

public void testDinamond(){

    List<String> list = new ArrayList<String>();
    Map<String, List<String>> map = new HashMap<String, List<String>>();
}

Java7:

public void testDinamond(){
    List<String> list = new ArrayList<>();
    Map<String, List<String>> map = new HashMap<>();
}

When we write code in Java 6 syntax, NetBeans will warn us to convert it into Java 7 Diamond Syntax:

To

Multi-Catch Similar Exceptions:

Before:

    public void testMultiCatch(){

        try {
            throw new FileNotFoundException("FileNotFoundException");
        } catch (FileNotFoundException fnfo) {
            fnfo.printStackTrace();
        } catch (IOException ioe) {
            ioe.printStackTrace();
   }

Java 7:

    public void testMultiCatch(){

        try {
            throw new FileNotFoundException("FileNotFoundException");
        } catch (FileNotFoundException | IOException fnfo) {
            fnfo.printStackTrace();
        }
    }

Same thing here. NetBeans will ask to convert the code into Java 7:

To

Try with Resources:

Before:

    public void testTryWithResourcesStatement() throws FileNotFoundException, IOException{

         FileInputStream in = null;
        try {
            in = new FileInputStream("java7.txt");

            System.out.println(in.read());

        } finally {
            if (in != null) {
                in.close();
            }
        }

    }

Java 7:

    public void testTryWithResourcesStatement() throws FileNotFoundException, IOException{

        try (FileInputStream in = new FileInputStream("java7.txt")) {

            System.out.println(in.read());

        }
    }

Same thing here:

To:

There is also varargs simplification, but I did not understand this one very well to code an example.

There are another features that were submited, but did not make it into this release:

• Elvis Operator
• List and Maps Index
• Collection Literals
• Null-Safe navigation

The code presented on this post is not only theory, I really ran it in my machine. You can get/download the NetBeans project from my github: https://github.com/loiane/Java7HelloWorld

A quick update: A DZone released today a RefCardz about NetBeans and Java 7 – it is a pdf and the download is free: http://refcardz.dzone.com/refcardz/netbeans-ide-7-programming

Filed in: Java | Tags: Java, Java 7, NetBeans 7, Project Coin