JLaunch (Java Launcher) Frequently Asked Questions (FAQ) have been documented here. If there is something regarding JLaunch that you are unsure about, please take the time to read these FAQ's before sending questions via email.

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What is JLaunch?

JLaunch is a small, lightweight executable program that can be used to cleanly start a Java Application. As many Java developers know, running Java applications can involve many configuration settings programmed into a batch file, and running from a batch file pops up an ugly DOS box while the application boots up.

Other installation issues affect Java programs. How does a software developer ensure that the correct version of the Java Runtime Environment has been installed on the user's machine? How do you guard against users running against a previous version? How do you configure your Java startup file to automatically detect an installed Java Runtime Environment, and automatically begin to use it? These issues and more are covered cleanly by JLaunch. Read on.

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How does JLaunch work?

Everything JLaunch needs to execute your Java application is contained in a simple configuration text file (JLaunch.cfg). You can open and edit this file using Notepad.

The JLaunch configuration file only contains two settings that are absolutely mandatory. The rest can be left blank, or filled in as desired.

Set the two mandatory settings in the configuration file, and you are on your way!

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JLaunch Configuration

The JLaunch configuration file (JLaunch.cfg) is a simple text file, containing all the necessary settings to launch your Java application. This file contains two types of settings; mandatory settings and optional settings. See below for details of each.

For easy and automatic configuration setting, use the JLaunch Configurator application to create new configuration files for your applications. The Configurator automates the process of building CFG text files for launching existing and new applications.

This application is easily renamed. If you require an EXE file with a different (or more appropriate) file name, simply rename JLaunch.exe to something else, eg. MyChess.exe. If this is done, you will need a corresponding CFG file to accompany it, eg. MyChess.cfg. It's as simple as that.

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JLaunch Configurator (Application)

The Configurator Application is a Java-based application that uses a wizard-like interface to help you modify and create new configuration files for your Java applications. As such, this program relies on Sun's Java Runtime Environment (JRE) 1.3, or above. Please ensure that you download the JRE from Sun, and install it before running the Configurator.

As mentioned in the JLaunch features below, if you run the Configurator without an appropriate JRE installed, you will be prompted to download and install the JRE when you start the application (see java.download below).

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Mandatory JLaunch Settings

Opening the JLaunch.cfg file, you will see two mandatory settings:

- app.title
- java.class.main

The app.title setting allows you to specify the human readable Title of your Java application. This could be text such as "Email Chess v2.4". For example:

app.title=Email Chess v2.4

This is used to prompt the user if a startup error occurs, or the user is prompted with dialog box information. The second setting is java.class.main, this is the Java class name of the executable class to load. This class should contain the 'main' method of the application. If this class exists in a package structure, provide the full package prefix with the class name. For example:

java.class.main=au.com.magisystems.app.ChessApp

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Optional JLaunch Settings

The remaining JLaunch configuration settings are completely optional. These settings will only come into effect when they are included in the configuration file. These settings are:

- java.runtime.exe
- java.classpath
- java.options
- java.params
- java.version
- java.version.only
- java.jre.only
- java.jdk.only
- java.debug
- java.download
- splash.image
- splash.minimum.display

These optional settings are described below.

java.runtime.exe allows you to specify the location of the Java Runtime Environment executable file (javaw.exe). It is highly recommended that you leave this setting blank when you release your software, as each user may have a different hard drive location for the Java Runtime.

When blank, JLaunch inspects the Windows Registry looking for the Java Runtime Environment installation, and then writes back to the configuration file the correct location of the runtime executable (javaw.exe). If the Java Runtime Environment is not found, or the version is not suitable, the user will be notified. As a last resort, a File Search common dialog is popped up to allow the user to navigate the hard drive and manually specify the location of the runtime.

java.classpath allows you to explicitly set the classpath. This may be required if your application is complex, and requires multiple Jar archives or code libraries present at runtime. Anything specified here is appended to the -classpath option when executing javaw.exe.

java.options allows you to explicitly set other java command line options, such as -D options, etc. For a full list of valid java options, open a DOS box and type JAVA [enter] to see a list.

java.params allows you to specify application parameters for your Java application, which are typically added to the end of the Java command line. These will become command line arguments to your program's main method (main entry point).

java.version allows you to specify the minimum Java version required to run your application. If your application requires Java 1.3 or above, you may decide to set this to 1.3, or 1.3.0, to limit users to this version or above. If an installed version of Java is found, but is not a large enough version, the user will be notified.

java.version.only allows you to indicate that the java.version setting you have provided (above) is the only version of Java that your application should run against. This will notify the user if that version of Java is not found on their system.

java.jre.only allows you to indicate that JLaunch should only attempt to detect Java Runtime Environment (JRE) installations, rather than both JRE and JDK installations.

java.jdk.only allows you to indicate that JLaunch should only attempt to detect Java Development Kit (JDK) installations, rather than both JRE and JDK installations.

java.debug allows you to turn on JLaunch debugging while setting up your launcher configuration settings. This will tell JLaunch to use debug popups during the startup process to inform you of it's progress, or of any problems / issues. Once your configuration is complete, you should remove the debugging for final distribution.

java.download allows you to provide an Internet Web Address of the page used to download the correct version of the Java Runtime that your software requires. When this entry is present, if JLaunch detects that a user does not have a Java Runtime installed, or that the version installed is inappropriate for your application, they will be given the option to navigate the web for the Java Runtime installer.

splash.image allows you to provide the file location of a 256 color BMP file to display as a Splash Screen while your application starts. This can be very useful in giving the impression of a faster startup time, particularly as Java applications are notoriously slow at startup. If this setting is non-blank (ie. valid) then the image is loaded first, and the Splash Screen is displayed first, before the application is loaded. The mouse cursor over the Splash Screen is also set to an hourglass while the startup occurs. The Splash Screen starts up Always On Top, so that your application window will appear below it when it displays.

splash.minimum.display allows you to specify a minimum time for displaying the Splash Screen. This may be a problem if your application is a particularly fast loader, in which case the Splash Screen may only be visible for a fraction of a second. Setting a minimum display time of one or two seconds gives your application a more professional feel.

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How Can I Customize The Icons?

The JLaunch application comes complete with a set of "default" icons to select from. If you prefer to use icons of your own design, this can be accomplished in a number of ways:

• Use a Windows Resource Editor
• Send Magi Systems Your Icon

We recommend the use of a Windows Resource Editor to store an icon of your choice into the current JLaunch executable (exe) file. There are a number of software tools currently on the market that provide this feature.

One such tool is the Resource Tuner product released by Heaventools. This tool will allow you to insert an icon of your choice into the JLaunch.exe file.

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Buy JLaunch

JLaunch is easy to register. For a registration fee of US $30 (or AU $45) Magi Systems can email you a fully registered version of JLaunch install set (without the 30 day timeout limitation).

Electronic Payment - PayPal

You can register using the secure PayPal Service and a credit card for US $30.
Click on the registration link below: