* The latest Java Runtime Environment 1.5.
You need at least Version 1.5 (called Java5 or "Tiger").
download the latest Java5 executable.
binary installer which you have to execute from a console.
distribution, you may use unofficial precompiled packages.
The package is called sun-j2se5.0-jre-binary.
Microsoft Windows people launch by double clicking on the jar file.
"java -jar josm-latest.jar" in the directory that holds the file.
MacOS people just click on the jar-file.