Overview

You need Java 7 and the JAVA_HOME variable set for some stubborn legacy build or a tool that refuses to move on. This guide gets you the JDK, shows how to install it on Windows and Linux, walks through setting JAVA_HOME and verifies the setup from the command line. Yes this still matters in the year of newer Java versions.

Get the Java 7 JDK

Download the JDK from the Oracle archive or use a trusted package repository. If a modern Java is acceptable pick that instead to save yourself future pain. On Linux the system package manager is the easiest option when available.

Install the JDK

Windows

Run the installer and follow the wizard like a functioning human. If you prefer scripts you can install the MSI or unpack an archive and then set environment variables with the command shown later. A common installation path looks like

C\Program Files\Java\jdk1.7.0_xx

Linux

Use your distro package manager or extract a tarball into a predictable location. Example for Debian style systems

sudo apt-get install openjdk-7-jdk

If you manually unpacked a tarball move the JDK folder to a stable path such as /usr/lib/jvm so tools can rely on it.

Set JAVA_HOME

Windows

Open System Properties and Advanced Environment Variables and add a new system variable named JAVA_HOME with the path to your JDK. For scripted installs use the setx command shown here

setx JAVA_HOME "C\Program Files\Java\jdk1.7.0_xx"

Important note that the new value only appears in new shells. Close and reopen any command prompt windows or restart your IDE to make it notice the change.

Linux

Edit your shell profile such as ~/.bashrc or a system profile script and add an export line. Example

export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64

Save and reload the profile with a new shell or with source ~/.bashrc if you must avoid a reboot. Yes you will still have to reopen terminals.

Verify the installation

Confirm the JDK is usable and that the environment variable points at the right place. Run these commands in the appropriate shell

java -version
# on Linux
echo $JAVA_HOME
# on Windows in cmd
echo %JAVA_HOME%

If java -version prints a Java 7 runtime and the echo output shows the JDK path you are golden. If not double check the path and remember Windows paths differ from Linux paths. Mixing them is a fast path to confusion.

Troubleshooting and tips

• If a build still uses the wrong Java check for tool specific settings or bundled runtimes that override JAVA_HOME.
• In CI set JAVA_HOME in the runner configuration or use container images that already include the right JDK.
• If you can, plan a migration off Java 7 to a supported release to avoid security and compatibility grief later.

This guide covered obtaining the JDK installing it on Windows and Linux setting JAVA_HOME and verifying the setup. Follow the platform specific steps and keep your paths sensible unless you enjoy debugging path related drama.