Mastering Netbeans: Master building complex applications with NetBeans to become more proficient programmers

Usually, installing the latest released version of NetBeans is the best course of action. With NetBeans, however, it is possible to download and install the previous versions or even daily builds.

To download the previous released versions of NetBeans, browse to the NetBeans download page at http://www.netbeans.org/downloads and click on the Archive link in the top-right corner of the page, as shown in the following screenshot:

From the resultant page, select the previous release you wish to download (for example, NetBeans 7.3) and then click on the Continue button. From here, you can choose whether to download the Java SE, Java EE, or All distributions of NetBeans. The following screenshot shows the previous versions of NetBeans that are currently available for download:

To download the latest daily build of NetBeans, simply click on the Development link in the top-right corner of the NetBeans download page. Again, from the resulting page, select the download bundle (Java SE, Java EE, or All) you require and follow the standard NetBeans installation procedure for your operating system, as outlined previously.

When installing NetBeans, a special directory is created on your computer that stores all the user configuration data for NetBeans; this folder is referred to as a userdir or user directory. This folder contains information on what plugins you have activated in NetBeans, what editor settings you've configured, and much more data. In fact, everything that makes your instance of NetBeans unique to you is stored in this folder.

On Mac OS X, the user directory is located at ~/Library/Application Support/NetBeans.

On Windows, it is located at c:\Users\<user>\AppData\Roaming\NetBeans.

On Linux, the user directory is located at ~/.netbeans.

In the user directory are the separate directories for each different version of NetBeans that you have installed. With this technique, it is therefore possible to have different configurations for different versions of NetBeans that are installed.

In addition to a user directory, NetBeans also makes use of a hidden cache directory, often referred to as a cachedir. The cache directory contains large amount of cache data and thus, it can become a large directory. Due to the information that's written into the cache directory, it must be stored in a different location to the user directory. The contents of the cache directory can be deleted without any settings being lost; it will be recreated the next time NetBeans is executed.

On Mac OS X, the cache directory is located at ~/Library/Caches/NetBeans.

On Windows, the cache directory is located at c:\Users\<user>\AppData\Local\NetBeans\Cache.

On Linux, the cache directory is located at ~/.cache/netbeans.

An easy way to find out the location of the user and cache directories is to display the NetBeans About dialog. In this dialog, the location of these directories is given along with the information about the version of NetBeans and Java that are in use:

If you just want to look at the NetBeans source code and aren't interested in making changes, you can download the source as a .zip archive from the relevant download page for any release. At the bottom of each download page, there is a link to download the source in the ZIP file format, as shown in the following screenshot:

The alternative to downloading a ZIP archive of the NetBeans source code is to clone the code from the NetBeans Mercurial repository. To perform this operation, you must have the Mercurial client installed on your computer. It can be downloaded for Windows and Mac OS X. For Linux and Mac OS X, it can be installed via the operating system's appropriate package manager, for example, apt-get on Ubuntu or yum install on Fedora. The Mercurial site at http://mercurial.selenic.com provides all the details on how to install Mercurial.

The NetBeans source code can be cloned from Mercurial from either the command line or from within NetBeans. Let's first look at how to achieve this using the command line.

Having installed Mercurial, we are in a good position to clone the NetBeans source code using the hg clone operation.

The NetBeans source code is stored within several branches and tags in the Mercurial repository. The main development for the next version of NetBeans is performed within the main-silver branch. This branch contains the latest development that has been picked up by the latest automatic stable build of NetBeans.

To check out this branch, execute the following command from within a terminal or command prompt:

hg clone http://hg.netbeans.org/main-silver

If this is your first check out of a branch, Mercurial may take a long time to clone the repository. Depending on your computer and network connection, this may take several hours.

Due to the way Mercurial works, hidden files are created on the local filesystem during the first phase of a Mercurial clone operation. No console output is provided during the checkout phase either, so it may appear that the clone operation is not working correctly as there is no visible feedback that the sources are being cloned.

It's possible to tell Mercurial to output status information so that you can see that all is working correctly. This can be especially useful on the first clone of a branch, which can be a lengthy operation. To clone a branch and get status updates output to the console, we must add the --debug parameter onto the clone operation:

hg --debug clone http://hg.netbeans.org/main-silver/

After cloning the NetBeans source files from the Mercurial repository, we have many subdirectories within the main-silver directory, as shown in the following screenshot:

Cloning specific versions of NetBeans

In the previous section, we showed how to clone the main-silver branch from the NetBeans Mercurial repository. What if we don't want the latest cutting edge development, but want to look at the source code for a specific version of NetBeans?

Fortunately, each release of NetBeans has the source code tagged in the Mercurial repository, so it's possible to check out any older release going back to December 1999 (this is the first tagged release within Mercurial).

The complete list of tagged releases is available at http://hg.netbeans.org/releases/tags, as shown in the following screenshot:

To view any of these tagged releases, simply check out the releases branch and then change to the specified folder for the requested release.

To enable us to use Mercurial from within NetBeans, we must first ensure that NetBeans is configured with the location of the Mercurial executable—hg.exe on Windows and hg on Mac OS X and Linux.

To configure Mercurial within NetBeans, perform the following steps:

Once we've configured the Mercurial support within NetBeans, we can clone the source code repository by performing the following steps:

The NetBeans source code is available to browse online at http://hg.netbeans.org/main/file. Viewing the source code this way can be very useful for the casual observer who wants to see how something is done within the NetBeans source code, but does not want to download the entire source code to their computer.

The following screenshot shows the top level of the NetBeans source code in a browser window:

To build NetBeans via the command line, open up a terminal or command prompt and change the directory to the directory containing the source code. Executing the ant command will build the source code, downloading any external dependencies that are required:

[david:~/Develop/NetBeans/main-silver]$ ant

If you are running JDK 8 instead of 7, you will be presented with an error when attempting to build the source code stating that builds are forbidden when using JDK 8. This error is presented so as not to introduce any Java 8 features into the source code.

If you wish to use JDK 8 to build the code, you can set the permit.jdk8.builds property to true:

[david:~/Develop/NetBeans/main-silver]$ ant –Dpermit.jdk8.builds=true

Alternatively, if you have both JDK 7 and 8 installed, you can set the nbjdk.home property to point to a valid JDK 7 installation and the build will then complete using the specified JDK 7 instead of JDK 8.

Once you have successfully build NetBeans, you can execute the freshly built instance by executing the ant tryme task:

[david:~/Develop/NetBeans/main-silver]$ ant tryme

This will execute the instance of NetBeans that you have just built using <build-location>/nbbuild/testuserdir as the user directory. The actual instance of NetBeans is stored within the <build-location>/nbbuild/netbeans folder.

Alternatively, you can also start the freshly-built instance of NetBeans by executing the netbeans or netbeans.exe commands from within the <build-location>/nbbuild/netbeans/bin directory, either from the command line of Windows / Linux explorer or Mac OSX Finder.

Now that we've seen how to build NetBeans via the command line, let's see how we can build it from within NetBeans itself.

If you cloned the NetBeans source code via the team support in NetBeans, then the NetBeans Build System project will already be opened within NetBeans, ready for building, as shown in the following screenshot:

If you cloned NetBeans via the command line, you will need to open the NetBeans Build System project located within the main-silver/nbbuild directory.

After opening the project, you will see that there are error badges shown against the Ant Tasks and Tests for Ant Tasks project nodes within the Projects window. These errors simply indicate that artifacts needed for the build haven't been downloaded yet; the build process will download the necessary files, and once built, these error badges will no longer appear.

To start building NetBeans, we must first build the necessary Ant tasks that the full build process relies on. To perform this, right-click on the NetBeans Build System project and select the Build option:

Once the build system is completed with no errors (you will see several warnings displayed during the build process, but these can be safely ignored), you can build NetBeans by right-clicking on the NetBeans Build System project and selecting the Build IDE (No ZIP File) option:

If you are using JDK 7, you will see that NetBeans is built correctly after a few minutes of activity.

If you are using JDK 8, you will see a failure message in the NetBeans output window, indicating that the project cannot be built using JDK 8, as shown in the following screenshot:

Since NetBeans provides its own installation of Ant to build projects, if we wish to use JDK 8 to build NetBeans, we must configure the permit.jdk8.builds property before attempting to build.

To configure the Ant properties from within NetBeans, perform the following steps:

Now that we've configured the permit.jdk8.builds property for the internal instance of Ant, we can build the project successfully using JDK 8. This is achieved by right-clicking on the NetBeans Build System project within the Projects window and selecting the Build IDE (No ZIP File) option.

Earlier in this chapter, we discussed the NetBeans user and cache directories and what information is stored within them. If you wish to change the user directory for a specific instance of NetBeans (for example, you may want to use a completely fresh user directory or a user directory from a previous installation of NetBeans), this can be achieved by specifying the netbeans_default_userdir parameter. Similarly, the cache directory can be changed by specifying the netbeans_default_cachedir parameter:

netbeans_default_userdir="${DEFAULT_USERDIR_ROOT}/8.0.2"
netbeans_default_cachedir="${DEFAULT_CACHEDIR_ROOT}/8.0.2"

The NetBeans default startup options are probably the most likely of the command-line arguments that you'll need to change for NetBeans. These options are specified by the netbeans_default_options parameter:

netbeans_default_options="-J-client -J-Xss2m -J-Xms32m -J-XX:PermSize=32m -J-Dapple.laf.useScreenMenuBar=true -J-Dapple.awt.graphics.UseQuartz=true -J-Dsun.java2d.noddraw=true -J-Dsun.java2d.dpiaware=true -J-Dsun.zip.disableMemoryMapping=true""true"

The preceding example options are from a Mac OS X installation of NetBeans 8.0.2.

The first option (-J-client) specifies that the JVM for NetBeans will run as a client VM instead of server VM. The client VM is essentially useful for applications requiring fast startup or small footprints. The server VM is typically used where performance is more important.

The second set of options (-J-Xss2m -J–Xms32m –J-XX:PermSize=32m) define the default memory allocation sizes used by the JVM running NetBeans (the thread stack size, initial memory allocation pool size, and size of the permanent generation, respectively). These options are specific for different version of the JDK, and all of them may not apply to the version of the JDK you are using.

The final parameters specified in the default options ensure that certain optimizations are performed on the JVM to make it more stable and perform better. Some of these parameters are operating system-specific and may not exist on configuration files for different operating system.

By default, NetBeans uses the system-defined JDK to run the IDE (you'll remember this can be overridden using the --javahome argument to the NetBeans installer, as discussed earlier in this chapter). This can be overridden in the netbeans.conf file by defining the netbeans_jdkhome property to specify the base directory of a different JDK installation:

netbeans_jdkhome="/path/to/jdk"

It's not usually necessary to change the JDK that NetBeans uses as this is set at the time of installation. However, if you wish to use a newer (or older) JDK than the one used when you installed NetBeans, it can be configured with this variable.

If you wish to run NetBeans as a one-off instance and do not wish to edit the netbeans.conf file, you can pass the --jdkhome <jdk_home> parameter on the command line instead when launching NetBeans.

A NetBeans cluster is a directory on disk that contains a set of modules such as the NetBeans Platform or the Java EE support within the NetBeans IDE. Additional clusters can be configured within NetBeans by adding the directory in which the cluster resides onto the netbeans_extraclusters parameter:

netbeans_extraclusters="/absolute/path/to/cluster1:/absolute/path/to/cluster2""cluster2"

It is most likely that you will not need to define the additional module clusters to be loaded at the startup unless you are developing NetBeans rich client platform (RCP) applications.

Several other NetBeans command-line arguments are available that provide more control over the NetBeans user experience.

To run NetBeans in a locale different from that of the operating system, the --locale option can be used. For example, --locale en:GB runs NetBeans with the en:GB locale.

If you wish to increase the base font size of NetBeans, the --fontsize option allows this to be achieved. For example, --fontsize 20 increases the base font size to 20px. This can be useful when demoing code or showing NetBeans to larger audiences.

The full list of different command-line options that are available within NetBeans is provided at http://wiki.netbeans.org/FaqStartupParameters.