How do I check if Java is installed?

In the Java Control Panel, click on the Java tab. Verify that the latest Java Runtime version is enabled by checking the Enabled box . Click OK in Java Control Panel window to confirm changes and close the window. Try to run same applet and verify it is now running using latest version of Java installed in your system.

Going to a command line and typing java -version can tell us for sure if Java is installed.

Java Version under Windows Start Menu – Java 7 Update 40 (7u40) and later versions

Q: How can I tell if Java Runtime Environment is installed on my Windows machine?