Learn how to install Java JDK (Java Development Kit) and update the PATH environment variable. For detailed instructions, see Oracle's official documentation: JDK Installation for Microsoft Windows.

Install Java JDK

Java JDK allows developers to write Java applications. Although you may not be writing Java scripts in your ebook, Kotobee requires Java JDK in some steps, like creating a random keystore for your Android mobile app. The standard Java, which you probably already have, is called Java JRE (Java Runtime Environment). 

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Although installing Java JDK is fairly easy, the installation can sometimes seem to take no effect, particularly on Windows. In such cases, the computer is still using the old Java version (JRE), instead of Java JDK. Follow the steps in the next section as provided by Oracle.

Updating the PATH Environment Variable (Optional)

You can run the JDK without setting the PATH environment variable, or you can optionally set it so that you can conveniently run the JDK executable files (javac.exe, java.exe, javadoc.exe, and so forth) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable file every time you run it, such as:

C:\> "C:\Program Files\Java\jdk1.7.0\bin\javac" MyClass.java

It is useful to set the PATH variable permanently so it will persist after rebooting.

To set the PATH variable permanently, add the full path of the jdk1.7.0\bin directory to the PATH variable. Typically, this full path looks something like C:\Program Files\Java\jdk1.7.0\bin. Set the PATH variable as follows on Microsoft Windows:

  1. Click Start, then Control Panel, then System.

  2. Click Advanced, then Environment Variables.

  3. Add the location of the bin folder of the JDK installation for the PATH variable in System Variables. The following is a typical value for the PATH variable:

    C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files\Java\jdk1.7.0\bin


  • The PATH environment variable is a series of directories separated by semicolons (;) and is not case-sensitive. Microsoft Windows looks for programs in the PATH directories in order, from left to right. If you are using Windows 10, the directories will appear in a vertical list:
  • You should only have one bin directory for a JDK in the path at a time. Those following the first instance are ignored.
  • If you are not sure where to add the path, add it to the right of the value of the PATH variable. In the case of Windows 10 (the screenshot above), click on New and add the path separately in a new entry.
  • The new path takes effect in each new command window you open after setting the PATH variable.

This video tutorial will walk you through installing Java JDK, and show you how to set the environment variables. The video will start at 1:30, when updating the PATH environment variable begins.