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Svetovid-lib Installation

Since the library is not a part of the standard Java Virtual Machine it is necessary to direct the compiler to use it. Following are several ways to use the library directly with a java compiler, notes about it’s usage in some editors, as well as a simple way to test if the installation was successful.

Install scripts

The library arhive should come with scripts for the installations. They are also available in the source tree on github. These should enable the library system-wide, using the CLASSPATH method described below.

Adding the jar explicitly to the compilation

It is possible to add jar files to be used during compilation as a command line parameter, or setting it up in most development environments.

For instance, if the jar is in the current folder, the appropriate line for compilation would be:

javac -cp svetovid-lib.jar Example.java

This is also applicable without administrative privileges if the jar is put into the current folder.

Unpacking into the current directory

The simplest way to enable the usage of Svetovid in programs is to extract all the class files into the current directory. This is also very convenient since it doesn’t need any administrative or elevated privileges on the computer and it therefore always applicable.

Adding the jar to the CLASSPATH

Java uses an environmental variable called CLASSPATH to look for classes and packages. It can be customised for the current user or system-wide. Adding the jar into this variable means that any compilation and running of a Java program will use the library as necessary. This is equivalent to using the -cp option as explained before, or in other words, it is like the parameter is being passed every time.

It is recommended for the user to look up the instructions for changing environmental variables for their operating system.

Also note that the jar file need to be kept in the place that is listed in the CLASSPATH, so it is recommended that it is kept in a logical place, such as the user home, or a dedicated lib folder.

Using the library with the Eclipse IDE

Using the library in Eclipse should work without additional konfiguration if the library was already added to the adequate JDK/JRE. Alternatively the library can be added to the classpath of a specific project.

However, sometimes there is a need for additional interventions, since the IDE will be reporting errors that the class Svetovid (or some other from the library) can not be found, or can not be used.

The root of the problem seems to be that Eclipse is caching the list of libraries when detecting Java Virtual Machines. This can lead to a confusing situation where the library is listed in the side panel in the classpath, while not being actually used by the internal compiler.

There are several methods that can help with this problem, listed below from the simplest.

Testing the installation

To simplify the testing whether the installation was successful, the main method of the class Svetovid will print out the version of the currently installed of the library.

Running

java Svetovid

will either display the version if the current JVM sees the library, or will report an error otherwise.

Deprecated instructions

Adding the library system-wide to all JVM (version 8 and earlier)

This option was deprecated in Java version 9.

Possibly the best solution is to expand the list of libraries used by the Java Virtual Machine, since then it is usable in any directory without additional effort. The only necessary step is to add svetovid-lib.jar to the system-wide lib/ext folder. This of course requires administrative privileges on a computer.

The target directory Under Windows is: %SystemRoot%\Sun\Java\lib\ext

while Linux machines use: /usr/java/packages/lib/ext

More details about the ext folder

Using the library in DrJava editor

This editor can compile programs successfully only with Java versions 8 and earlier, and is therefore not recommended anymore.

To be able to use the library to run programs in the Interactions panel of DrJava, the jar file must be added to the editors classpath.

The simplest way to achieve this is to obrain a modified version of the editor that has svetovid/lib already integrated in it. Jar files with the latest stable version of the library are available on the official website.

Of course it is possible to use an unmodified editor and to configure it adequately by hand.

The settings can be found here:

Alternatively the following line can be added to the .drjava file in the users home directory to achieve the same effect:

extra.classpath=path/svetovid-lib.jar

To use this method administrative privileges are not needed since the jar file can located at any directory.

If the library is added system-wide, programs will compile successfully in DrJava, but the interactions panel will report an error, since DrJava doesn’t seem to use this ext directory.

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