One question that a lot of beginning programmers have is: "Now that I've created my application in the IDE, how do I get it to work from the command line outside of the IDE." Similarly, someone might ask, "How do I distribute this application to other users without having to give them the whole IDE as well?"
The answers to these questions are relatively simple, but not necessarily obvious. This document addresses those questions by taking you through the basics of using NetBeans IDE to prepare your applications for distribution and then deploying those applications. In addition, this document provides information that you might need to configure your system (or which you might need to pass on to the users of your application). We will show a few different approaches for deploying an application, so that users can access the application by:
Along the way, we will cover some basics of JAR file structure and how JAR files are dealt with inside IDE projects.
Expected duration: 30 minutes for the main exercise and 15 minutes for the optional exercise.
This tutorial has no prerequisites.
|Software or Resource||Version Required|
|NetBeans IDE||Java SE, Java, or All bundle|
|Java Development Kit (JDK)||version 6 or
Download the DeploymentTutorial.zip file and unpack it on to your system. This zip file contains source files for the application plus a few other files that will be useful for the tutorial.
On Microsoft Windows systems, use WinZip or similar archive packaging software to extract the files.
To unpack the zip file on a UNIX platform, change directories to the location of the zip file and type the following in a terminal window:
$ unzip DeploymentTutorial.zip
The goal of this exercise is to show you how to create a distributable application from the IDE and then run that application from outside of the IDE. We will package the application in the form of an executable JAR file. A JAR file is an archive file that can contain multiple files and folders. JAR files are similar to zip files, but JAR files can have additional attributes that are useful for distributing Java applications.
In this exercise, you create an IDE project and then place two pre-written Java source files into that project. Then you will compile the classes and build an executable JAR file. Afterwards, you will learn how to run the JAR file from outside of the IDE.
These classes implement features of the GNU grep utility, which can be used for searching text or regular expression patterns inside text files. The project contains both command-line and GUI versions of the application, so that you can see different ways of running the application.
To set up the project:
For example, type AnotherGrep for Project Name. For the Project Folder field, you can just accept the default.
The project folder does not have to be in the same location as the source files that you are importing into the project.
The project opens in the IDE and becomes visibile in the Projects window. You can explore the contents of the project by expanding the project's Source Packages node, where you should see classes called Grep and xGrep. Grep.java is a console version of the application. xGrep.java is a GUI version of the application and uses methods defined in Grep.java.
At this point, you have all of the source code that you need to make the project work. However, there is some more configuration that you need to do. You need to:
In order for a user to easily run your JAR file (by double-clicking the JAR file or by typing java -jar AnotherGrep.jar at the command line), a main class has to be specified inside the JAR's manifest file. (The manifest is a standard part of the JAR file that contains information about the JAR file that is useful for the java launcher when you want to run the application.)
When you build a project, the IDE builds the JAR file and includes a manifest. When you set the project's main class, you ensure that the main class will be designated in the manifest when you later build the project.
To set the project's main class:
When you build the project later in this tutorial, the manifest will be generated and include the following entry:
If the project you are developing relies on code from other libraries, you need to point to those libraries from your project. This is necessary for your project to compile properly and for the application to be easily distributable.
You can add libraries to a project through the Libraries node of the project.
In this example, xGrep.java relies on the the new GroupLayout layout manager classes, which are not currently included in the JDK. (GroupLayout will be added to JDK 6.) For now, the GroupLayout classes are available in the Swing Layout Extensions library. The IDE includes the Swing Layout Extensions library in its Library Manager, so it easy to add to your project.
To add the Swing Layout Extensions library:
Note: If you find that the Swing Layout Extensions has already been added to your project, this might be a result of you having opened the xGrep.java file in the IDE. When you open a file that uses classes from the Swing Layout Extensions library or when you create an application using the Matisse GUI Builder, the IDE automatically adds the Swing Layout Extensions library to the project. The automatic adding of libraries in this fashion does not work for other libraries.
When you later build the project, the following entry is added to the application JAR file's manifest:
You can also add an arbitrary JAR file or folder (using the Add JAR/Folder command) or the output of another project (using the Add Project command).
Now that you have your sources ready and your project configured, it is time to build your project.
To build the project:
When you build your project:
Note: You can view the contents of the manifest in the IDE's Files window. After you have built your project, switch to the Files window and navigate to dist/AnotherGrep.jar. Expand the node for the JAR file, expand the META-INF folder, and double-click MANIFEST.MF to display the manifest in the Source Editor.
Main-Class: anothergrep.xGRep Class-Path: lib/swing-layout-1.0.jar
(To find more about manifest files, you can read this chapter from the Java Tutorial.)
When developing applications in the IDE, typically you will need to test and refine them before distributing them. You can easily test an application that you are working on by running the application from the IDE.
To run the AnotherGrep project in the IDE, right-clicking the project's node (AnotherGrep) in the Projects window and choose Run Project.
The xGrep window should open. You can click the Browse button to choose a file in which to search for a text pattern. In the Search Pattern field, type text or a regular expression pattern that you would like to match, and click Search. The results of each match will appear in the xGrep window's Output area.
Information on regular expressions that you can use in this application are available here and in many other places on the World Wide Web.
Once you have finished developing the application and before you distribute it, you will probably want to make sure that the application also works outside of the IDE.
You can run the application outside of the IDE by following these steps:
You will know that the application has started successfully when the xGrep window opens.
If the xGrep window does not open, your system probably does not have a file association between JAR files and the Java Runtime Environment. See Troubleshooting JAR File Associations below.
Now that you have verified that the application works outside of the IDE, you are ready to distribute it.
You can distribute the application by following these steps:
The users of your application should be able to run it by double-clicking the JAR file. If this does not work for them, show them the information in the Troubleshooting JAR File Associations section below.
On most systems, you can execute an executable JAR file by simply double-clicking the JAR file. If nothing happens when you double-click the JAR file, it might be because of either of the following two reasons:
If the JAR file type is associated with a JRE, the icon that represents that file should include a Java logo.
Note: Sometimes JAR file associations are switched by software that you install, such as software to handle zip files.
To add the JAR file association on Microsoft Windows systems:
On Windows XP, you can check for installed versions of the JRE by choosing Start > Control Panel > Add or Remove Software.
If there is not a JRE on the system, you can get one from the Java SE download site.
If you have a JRE installed on your system but the file association is not working, continue with the steps below.
If JAR files are associated with the Java Platform SE Binary on your system but double-clicking still does not execute the file JAR file, you might need to specify the -jar option in the file association.
To specify the -jar option in the file association:
-jar "%1" %*Afterwards, the field should contain text similar to the following:
"C:\Program Files\Java\jre1.6.0_14\bin\javaw.exe" -jar "%1" %*
For UNIX and Linux systems, the procedure for changing file associations depends on which desktop environment (such as GNOME or KDE) that you are using. Look in your desktop environment's preference settings or consult the documentation for the desktop environment.
The goal of this exercise is to show you some ways that you can start your application from the command line.
This exercise shows you how you can start a Java application in the following two ways:
You can launch an application from the command line by using the java command. If you want to run an executable JAR file, use the -jar option of the command.
For example, to run the AnotherGrep application, you would take the following steps:
java -jar AnotherGrep.jar
If you follow these steps and the application does not run, you probably need to do one of the following things:
C:\Program Files\Java\jdk1.6.0_14\bin\java -jar AnotherGrep.jar
If the application that you want to distribute is a console application, you might find that it is convenient to start the application from a a script, particularly if the application takes long and complex arguments to run. In this section, you will use a console version of the Grep program, where you need to pass the arguments (search pattern and file list) to the JAR file, which will be invoked in our script. To reduce typing at the command line, you will use a simple script suitable to run the test application.
First you need to change the main class in the application to be the console version of the class and rebuild the JAR file:
After completing these steps, the JAR file is rebuilt, and the Main-Class attribute of the JAR file's manifest is changed to point to anothergrep.Grep.
Inside PROJECT_HOME, there is a grep.sh bash script. Have a look at it:
#!/bin/bash java -jar dist/AnotherGrep.jar $@
The first line states which shell should be used to interpret this. The second one executes your JAR file, created by the IDE inside PROJECT_HOME/dist folder. $@ just copies all given arguments, enclosing each inside quotes.
This script presumes that the Java binaries are part of your PATH environment variable. If the script does not work for you, see Setting the PATH Environment Variable.
More about bash scripting can be found here.
On Microsoft Windows systems, you can only pass nine arguments at once to a batch file. If there were more than nine arguments, you would need to execute the JAR file multiple times.
A script handling this might look like the following:
@echo off set jarpath="dist/AnotherGrep.jar" set pattern="%1" shift :loop if "%1" == "" goto :allprocessed set files=%1 %2 %3 %4 %5 %6 %7 %8 %9 java -jar %jarpath% %pattern% %files% for %%i in (0 1 2 3 4 5 6 7 8) do shift goto :loop :allprocessedThis script is included inside PROJECT_HOME as grep.bat so you can try it out.
The nine arguments are represented inside the batch file by %<ARG_NUMBER>, where <ARG_NUMBER> has to be inside <0-9>. %0 is reserved for the script name.
You can see that only nine arguments are passed to the program at a time (in one loop). The for statement just shifts the arguments by nine, to prepare it for next loop. Once an empty file argument is detected by the if statement (there are no further files to process), the loop is ended.
More about batch scripting can be found on this page.
If you can not run a Java class or JAR file on your system without pointing to the location of the JDK or JRE on your system, you might need to modify the value of your system's PATH variable.
If you are running on a Microsoft Windows system, the procedure for setting the PATH variable depends the version of Windows you are using.
The following are the steps for setting the PATH variable on a Windows XP system:
For example, if your JRE is located at
C:\Program Files\Java\jdk1.6.0_14you would add the following to the end of the PATH variable:
If you are running on a UNIX or Linux system, the instructions for modifying your PATH variable depends on the shell program you are using. Consult the documentation of the shell that you are using for more information.
For more information on working with NetBeans IDE, see the Support and Docs page on the NetBeans website.
To send comments and suggestions, get support, and keep informed on the latest developments on the NetBeans IDE development features, join the email@example.com mailing list.
You also might want to consider using Java Web Start technology, which enables users to click once to download and run a client-side application.