Downloading and Installing JDK

1. JDK Versions

1.4. How To Set the Environment Variable JAVA_HOME

Many Java applications (such as Tomcat) require the environment variable JAVA_HOME to be set to the JDK installed directory.

To set the JAVA_HOME environment variable:

1. First, find your JDK installed directory. For JDK 11, the default is "c:\Program Files\Java\jdk-11.0.{x}", where "{x} is the update number. Use your "File Explorer" to find this directory and take note of your update number {x}.
2. Check if JAVA_HOME is already set. Start a CMD and issue:

set JAVA_HOME

If you get a message "Environment variable JAVA_HOME not defined", proceed to the next step.
If you get "JAVA_HOME=C:\Program Files\Java\jdk-11.0.{x}", verify that it is set correctly to your JDK directory. If not, proceed to the next step.

3. To set the environment variable JAVA_HOME in Windows 10:

a. Launch "Control Panel" ⇒ (Optional) "System and Security" ⇒ "System" ⇒ Click "Advanced system settings" on the left pane.

b. Switch to "Advanced" tab ⇒ Click "Environment Variables"

c. Under "System Variables" (the bottom pane) ⇒ Click "New" (or Look for "JAVA_HOME" and "Edit" if it is already set) ⇒ In "Variable Name", enter "JAVA_HOME " ⇒ In "Variable Value", enter your JDK installed directory you noted in Step 1. (In the latest Windows 10: you can push the "Browse Directory" button and navigate to the JDK installed directory to avoid typo error.)

4. To verify, RE-START a CMD (restart is needed to refresh the environment variables) and issue:

set JAVA_HOME
JAVA_HOME=c:\Program Files\Java\jdk-11.0.{x}   <== Verify that this is YOUR JDK installed directory

Notes: Windows' environment variables (such as JAVA_HOME, PATH) are NOT case-sensitive.