Although the initial configuration is sufficient for most tasks, it may still be required to do some configuration. In the case of OpenJDK, this is performed by setting system variables. Here we will touch only on the case that often occurs when JDK is unpacked manually—how to set it as default.
To follow this recipe, we will need an OpenJDK instance installed on our Windows system. Windows 7 or Windows 8 will be best, because Windows XP is already officially discontinued by Microsoft.
At first, we need to install our OpenJDK implementation as the default Java instance. This is often necessary for development:
In order to do so, we will go to Start | Control Panel | System | Advanced | Environment Variables | User Variables (or System Variables for system-wide configuration) and add the path to the Java executable to the
PATHsystem variable, as shown:
If we were installing OpenJDK from unofficial builds, there may be no need to change the
PATHvariable at all.To validate our newly configured variable, we will go to the Command Prompt and type the following:
java -version
The expected output is the version of our newly installed build.
In order to set a newly installed OpenJDK instance as the default JDK, we need to change the system variable. After that change, our Java executables will be visible to the system.