Russ Harvey Consulting - Computer and Internet Services

Java Installation and Security

Maintenance | Downloads | About Java

Java Get Powered

Java Vulnerable

Java, along with Flash and Adobe Reader, has been known to make Windows insecure for some time. Mac and Linux users now share that vulnerability.

Remove Java if you don't need it. If installed, be sure to frequently update it and to uninstall older versions. See Java browser plugin recommendations.

Do You NEED Java?

Java is necessary only for certain features of LibreOffice, Apache OpenOffice and perhaps to allow other software to run on your computer.

If installed, I recommend disabling the Java plugin in your web browser — enabling it ONLY for trusted sites.

Java Maintenance

Update Java Regularly

Update Java whenever updates are available. These releases fix security flaws in Java.

Version 9 Pending

Java version 9 is scheduled for general release after which older versions will be unsafe to use.

This new version will remove all support for browser plugins, primarily because the major browsers no longer support them, largely a result of the rapidly growing mobile market that never supported Java.

Avoid Third-party Software

Prevent Java Updater from installing third-party software.

  1. Open the Java Control Panel: Start ⇒ Control Panel ⇒ Java. If you see categories in the Control Panel, look for Java in Programs.
  2. Click on the Advanced tab.
  3. Scroll down to the Miscellaneous section at the bottom and place a check mark in “Suppress sponsor offers when installing or updating Java.”

If you uninstall Java, this setting will be removed, but as long as you de-select any optional software when downloading new Java versions and check during installation you shouldn't see third-party software installed on your system.

Uninstall Older Versions

I recommend uninstalling all previous versions of Java when updating. Old and unsupported versions of Java are a serious security risk and can leave your system vulnerable.

Removing older versions of Java from your system ensures that Java applications will run with the most up-to-date security and performance improvements on your system. —Oracle

Java Updater May Not Remove Older Versions

Java's updater may not automatically remove all older versions, leaving your system vulnerable.

Oracle provides instructions for uninstalling out-of-date Java versions.

I recommend that you manually verify that older versions have been removed from your system.

Uninstall Option During Update

During installation of a new version, you should see the option to uninstall older versions:

Java Out of Date

You need to provide Java permissions to check for these and to enable Java (see Firefox & Java Security).

You can also run the Java Uninstall tool. See also, How do I uninstall Java on my Windows computer?

Uninstall Java when Updating

To secure your computer I recommend that you manually uninstall all current versions, cleaning out any remaining Java-related AppData entries before installing the most recent version available so you're running only the most recent version.

Manually Checking for Older Versions

Alternatively, you need to check to see if option to uninstall older versions has removed all older versions.

In either case, I recommend cleaning up the Java folders in AppData.

Cleaning Up AppData Java Folders

You need to be careful when following the instructions in this section. You can seriously harm your Windows installation if critical files are removed.

After running Java's Uninstall Older Versions option, I still found an obsolete Java version in the Sun AppData folder:

The Sun AppData folder still contains older versions of Java

Cleaning Up Java Folders in AppData

Be sure you've either uninstalled Java (all versions) or have run the option to uninstall outdated versions before proceeding.

Like most Windows programs, Java keeps data in AppData (in folders labelled Oracle and Sun in the LocalLow folder).

To clean up obsolete Java folders, follow these instructions:

  1. Navigate to the Java folders by opening the AppData then LocalLow folders.
  2. Look for the Oracle and Sun folders and delete the appropriate folder(s):
    • If you've uninstalled Java completely, you can delete both the Oracle and Sun folders.
    • If you've only removed outdated versions, open the Sun folder then delete any folders containing older versions that is present (the jre1.8._45 folder in the above example).

Locating AppData

The AppData folder is located in C:\Users\[user]\AppData. Navigate to the C: drive then open the Users folder and look for a folder with your user name. Inside you'll see the AppData folder (if you've made hidden files and folders visible).

Windows 10 users can use File Explorer to view the AppData folder. Windows 7 users can open their User folder (often located on their desktop) to view the AppData folder:

AppData folder in the User's Files folder

AppData Hidden by Windows

The AppData folder is normally hidden by Windows.

  • Windows 7 users can change this in the Folder Options in Control Panel to show hidden files, folders and drives in the View menu.
  • Windows 10 users can change this in File Explorer Options (search for “File Folder Settings”). Check “Show hidden files, folders and drives” in the View menu.

Firefox & Java Security

NPAPI-based plugins, including Java, are blocked in current versions of Firefox.

Beginning in Firefox version 52, support for NPAPI plugins in Firefox has ended, except for Adobe Flash. Some of the plugins that will no longer load include Java, Microsoft Silverlight and Adobe Acrobat. — Mozilla Support

Java Blocked in Legacy Versions

Java blocked in Firefox browers

Beginning with version 17, Firefox disabled the Java plugin on computers running Windows and running Java 7 Update 11 or earlier (the dark grey box on the right). Java warns you before allowing the vulnerability to be exploited.


Firefox displays a warning for Java 7 Update 13  when it is called on a website

You'll likely see a warning similar to the light grey one shown on the right for Java 7 Update 13 or later.

  • Be sure to allow Java to run ONLY on sites you trust. Java exploits can infect your computer.
  • I recommend not telling Java to remember the setting. The site may become dangerous in the future and the reminder that Java can be unsafe helps to keep you vigilant.

How to Use Java if it is Blocked

Mozilla support provides instructions on using Java if it's been blocked (e.g. for

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Java Downloads

Update to the Most Recent Version

Because security vulnerabilities are discovered all the time, it is recommended that you regularly update to the latest Java version and ensure older ones are removed.

Download Java

Download the latest version of Java for your operating system:

Most users only need the 32-bit version of Java. If you use a 64-bit version you'll need to maintain and update both versions.

Java for Linux

Java for Mac

Installing Java on the Mac has changed with newer version (Oracle's Java version 7u25 and below have been disabled by Apple in OS X).

  • Java 8 requires an Intel-based Mac running Mac OS X 10.7.3 (Lion) or later and administrator privileges for installation.
  • Apple supplied their own version of Java for Java versions 6 and below and used the Software Update feature on the Apple menu to check for the most current Java available for your Mac.
  • Apple's Get Java for your Mac now directs you to the Oracle site.
  • See Oracle's Java Downloads for All Operating Systems for offline installers for the Mac and the Mac download FAQ.

32-Bit Recommended

64-bit browsers have the potential for much faster browsing on 64-bit systems.

Most users have installed and used 32-bit browsers because support for 64-bit plugins was spotty at best (Java has been supported for both 32- and 64-bit browsers for some time).

However, with the move away from NPAPI plugins, it makes sense to move to a 64-bit browser.

If you do install the 64-bit version of Java and still maintain a 32-bit browser, you'll need to ensure that you update both the 32- and 64-bit versions.

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About Java

[Java is] a programming language and computing platform first released by Sun Microsystems in 1995. —Oracle

Java is most visible in online games such as those on and Yahoo Games as well as many phone- and tablet-based applications.

Enterprise-level Java applications run services for companies.

Oracle purchased Sun and along with it the rights to Java. Oracle is an established company long associated with corporate software.

Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners.

Java is a Cross-Platform Environment

Java is a cross-platform environment used to create regular programs that can run on virtually any operating system and on thousands of other devices.

The only requirement is that a Java “virtual machine” (JVM or JRE) is available for the operating system or device which translates Java into something the operating system or device can understand.

You might want to check out Oracle's Java SE Security so you understand the risks of installing and running Java.

Java Programs and Applets

The most common use of Java is still small programs called applets, but there are Java programs, especially in the emerging phone and tablet markets.

Java Development

Many Java resources are aging or obsolete. You can begin with these IBM developerWorks resources:

Learning More About Java

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Related Resources

Related resources on this site:

or check the resources index.

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Updated: December 6, 2017