PUBLIC MARKS from tadeufilippini with tags "java ubuntu" & "docs ubuntu"

Overview Sun Microsystems have developed Java, which is many things depending on who you ask. It is a language, and an execution environment and probably many more things. On this page Java refers to the software that executes programs compiled to Java byte codes (akin to machine language). Be aware of the Java trap. Although keep in mind that with the GPL licensing of the Sun Java implementation the Java trap is a thing of the past. Even RMS thinks so. Use IcedTea on Ubuntu 7.10 and OpenJDK on Ubuntu 8.04 or later. The first free project to offer substantial parts of Java platform functionality was Guavac. After that the free software movement developed java compilers, most notably the GNU Compiler for Java. GCJ is a front end to the GCC compiler which can natively compile both Java(tm) source and bytecode files. The compiler can also generate class files. Gcjwebplugin is a little web browser plugin to execute Java applets. It is targeted for Mozilla and compatible browsers that support the NPAPI. Others include the Eclipse Java Compiler, which is maintained by the Eclipse Foundation. Eclipse is an open-source Integrated development environment (IDE) written primarily in Java. The Eclipse open source community has over 60 open source projects. OpenJDK is the open source Java, derived from sources which will become OpenJDK 7 in the future.

Running Java under Ubuntu In order to run Java programs and Java applets, you must have a Java environment installed. The GCJ flavor of Java is installed as default, and is usually fine for most purposes. If it is not installed, JavaInstallation describes how to install some opensource flavors of Java. You may, however, have a need to run the Sun flavor of Java if something does not work correctly. To get Sun Java under Ubuntu 7.04 or later running on Intel or PowerPC platform, you should enable the Universe repository in Add/Remove programs, and install either the openjdk-6-jre package or the sun-java6-bin package. (Note: PowerPC version is slow). To get Sun Java under Ubuntu 6.06 or 6.10 running on Intel x86 platform, you should enable the Universe repository in Add/Remove programs, and install the sun-java5-bin package. Note: The same commands will work under Xubuntu/Kubuntu (using Add/Remove or the Adept Package Installer). Choosing the default Java to use Just installing new Java flavours does not change the default Java pointed to by /usr/bin/java. You must explicitly set this: * Open a Terminal window * Run sudo update-java-alternatives -l to see the current configuration and possibilities. * Run sudo update-java-alternatives -s XXXX to set the XXX java version as default. For Sun Java 6 this would be sudo update-java-alternatives -s java-6-sun * Run java -version to ensure that the correct version is being called. You can also use the following command to interactively make the change; * Open a Terminal window * Run sudo update-alternatives --config java * Follow the onscreen prompt