See my Defensive Computing blog at Computerworld.com  

What Version of Java Are You Using?

On a computer with multiple web browsers, be sure to check the Java version in every browser. I say this because multiple copies of Java can sometimes be installed with different browsers using different copies. Also, Java can be enabled in one browser and disabled in another.
Note: The portion of Java that runs programs is referred to as either the Java Run-time Environment (JRE) or the Java Virtual Machine (JVM).

 Method 1:  Ask Java

This is my favorite - straight from the horse's mouth (so to speak). The Java Run-time Environment is aware of its version and the company that authored it. So I wrote a very simple applet (the source code is on the About page) that gets this information from the JRE and displays it in a pink rectangle.

 Method 2: Windows Control Panel (updated Jan. 12, 2013)

Java, like any normal Windows application, shows up in the list of installed programs in the Control Panel. In Windows XP, select Add or Remove Programs. In Windows 7, click on Programs and Features. Note however, that just because Java is installed, does not mean that any particular web browser on your computer is using it. Java can be disabled system-wide or disabled in one particular browser.

For Java version 6, the Name column displays a user-friendly "Java (TM) 6 Update 37". This would appear at the top of this page as "1.6.0_37". The version column, under Windows 7, displays this same version information as 6.0.370. Yes, three different formats for the same information. This is typical with Java.

Java 7 appears as "Java 7 Update 10" in the Name column, but the version is 7.0.100.

In old days, Java version 1.5.0, looked like: "J2SE Runtime Environment 5.0 Update 6". J2SE meant Java. Runtime Environment refers to the JVM (Java Virtual Machine). 5.0 meant 1.5.0. Update 6 refered to the version of version 1.5.0. In English, it meant Java version 1.5.0_06. Way back, with Sun's Java version 1.4.2, the Control Panel entry looked like "Java 2 Runtime Environment, SE v1.4.2._06". This meant that version 1.4.2_06 was installed on the computer.

The Control Panel also offers access to the Java Control Panel (the "Java" entry). On the General tab, click the About button to see the installed version. This works for both Java 6 and Java 7.

 Method 3: OS X Snow Leopard 10.6 (updated Feb. 10, 2013)

Java 6 (from Apple, not Oracle) was pre-installed on Snow Leopard. Java 7 is not available.

To see the installed version of Java 6, go to the Applications -> Utilities folder and run the Java Preferences program.

Another way to see the Java version is with the

java -version

NOTE: Java 6 is updated on Snow Leopard using the standard Software Update feature of the operating system.

According to Oracle (Note for Users of Macs that Include Apple Java 6 Plug-in) there can be multiple copies of Java 6 installed. They say: "If you have not yet installed Apple's Java Mac OS X 2012-006 update, then you are still using a version of Apple Java 6 that includes the plug-in and the Java Preferences app. ... The Applications -> Utilities -> Java Preferences application is part of Apple's implementation of Java ... Under Apple's implementation of Java, it was possible to have multiple JREs installed, and the Java Preferences app was used to determine the first compatible version that would be used."

 Method 4: OS X Lions (Updated March 15, 2013 | Feb 10, 2013)

The situation on Lion (10.7) and Mountain Lion (10.8) is confusing. Java was not pre-installed by Apple. These systems can have either Java 6, Java 7 or both installed. Java 6 comes from Apple, Java 7 from Oracle. Each works a bit differently. For example, there can be multiple copies of Java 6 installed, but Java 7 only allows a single version. At the time this was written, I did not have access to a Mac running Lion or Mountain Lion, so I can not personally verify the below.

If Java 6 is the only installed version of Java, then determining its version is probably the same on OS X 10.7 and 10.8 as documented above for 10.6. However, Java 6 is able to run applets in web pages on Snow Leopard (10.6) but not in Lion (10.7) and Mountain Lion (10.8).

According to Oracle, there are two ways to determine the installed version of Java 7:

1. From System Preferences click the Java icon from the Other category. This launches the Java Control Panel. Click About...
   If there is no Java icon under System Preferences, then Java 7 is not installed.
   
   
2. Type the following in a Terminal window:

    % /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java -version

John Martellaro at Macobserver says that you can learn the installed version of Java 7 from the Java Control Panel (System Preferences -> Java). Go to the Java tab and click on the View button.

Updating Java 7: Java does not yet self-update. While the checking for new versions is automatic, the actual software update is manual. From the Apple menu, chose System Preferences, then View, then Java to see the Java Control Panel. Go to the Update tab and click on the Update Now button.

A Mac that was upgraded from Java 6 to Java 7 is the most confusing case. In October 2012, Paul Ducklin of Sophos wrote "Keeping track of which Java version you have, and whether it's the latest and most secure, can be a bit tricky, especially for Apple users." He notes that after the update, Java applications default to using version 6, whereas online applets default to version 7.

Apple's Java 6 was able to run applets (Java programs in web pages) on Lion and Mountain Lion until October 2012, when Apple upgraded Java 6 from Update 35 to Update 37 (see the Java for OS X 2012-006 update). According to Oracle, the 2012-006 update from Apple uninstalled the Apple-provided Java applet plug-in from all web browsers. This meant that to run Java applets on websites, Mac users needed to install Java 7 from Oracle. But the story does not end there.

Apple offers instructions (How to re-enable the Apple-provided Java SE 6 applet plug-in and Web Start functionality) on how to disable Java 7 and re-enable the Java 6 browser plug-in. And Oracles Mac OS X Platform Install FAQ has instructions for running Java 6 on an OS X system that has Java 7 installed, in a command line environment.

Note 1: An installed JRE from Oracle will not appear in the Java Preferences.app.

Note 2: If you are viewing this page with the Chrome browser on an OS X system with Java 7 installed, the applet at the top of the page will not work. This is because Java 7 on Lion and Mountain Lion is 64 bit, while Chrome is 32 bit. Java 7 on Lion and Mountain Lion works with Safari and Firefox.

Note 3: Oracles JRE 7 Installation for Mac OS X points out that Java 7 on a Mac is installed on a system wide basis, for all users, and that administrator privileges are required. Java 7 cannot be installed for a single user.

Note 4: Java 7 Update 6 and later requires OS X 10.7.3 (Lion) or later.

 Method 5: Java command on Windows

On Windows XP, open a command window and enter the following command

java -version

The output will look something like:

java version "1.6.0_31"
Java(TM) SE Runtime Environment (build 1.6.0_31-b05)
Java HotSpot(TM) Client VM (build 20.6-b01, mixed mode, sharing)

You can also use the command   "java -fullversion"   and produce output such as:

java full version "1.6.0_17-b04"

As of Windows 7, this no longer works (not sure about Vista). It produces the error shown below, which is also produced on an XP machine without any version of Java from Oracle installed.

'java' is not recognized as an internal or external command, operable program or batch file.

 Method 6:  Firefox on Windows (updated Jan. 11, 2013)

(1) Mozilla, the company behind Firefox, has a plugin checker page that both reports the installed version of Java and whether it is "up to date" or "outdated" (last verified with Firefox 18). Java 7 Update 10 is reported as "Java(TM) Platform SE 7 U10". Java 6 Update 37 is reported as "Java(TM) Platform SE 6 U37".

(2) In Firefox 18, do Tools -> Add-ons, then click on Plugins in the left side column. Java 6 Update 37 will display as "Java(TM) Platform SE 6 U37 6.0.370.6". It will also say "Next Generation Java Plug-in 1.6.0_37 for Mozilla browsers". Java 7 Update 10 will display as "Java(TM) Platform SE 7 U10 10.10.2.18". It will also say "Next Generation Java Plug-in 10.10.2 for Mozilla browsers".

(3) In Firefox 18, you can enter go to the address bar and enter:

about:plugins

Java 7 Update 10 is identified here as "Java(TM) Platform SE 7 U10." Java 6 Update 37 is identified here as "Java(TM) Platform SE 6 U37".

 Method 7: Windows Java Systray Icon (updated Jan. 12, 2013)

If the Java coffee cup is displayed in the Windows System Tray (a.k.a Notification area) you can right click on it and select "About Java Technology" to open a window showing the installed version of Java. The display of this Java icon is optional and can be configured in the Java Control Panel on the Advanced tab. In my experience, the default is to display the icon in Java 6 but suppress it in Java 7.

 Method 8: JavaScript

March 2010: This JavaScript based approach was offered by Malcolm at nuearth dot com. Sun provides a 16k JavaScript file with handy functions, one of which will test the version of Java installed.See their advice on using the script. DeployJava usage is described in the deployment toolkit script. The following sample script will check and see if the proper version of Java is installed and will display a message if not.

-- In Head----
   [script src="http://java.com/js/deployJava.js"][/script]
---In Bbody-----
[div id="dynamiccontent" ][/div]
[script type="text/javascript"]
deployJava.do_initialize();
var java_message ='Products XYZ requires Java 7 or higher. Download from www.java.com'
function altercontent()
{if( deployJava.versionCheck("1.7")==false )
    { if (document.all)  {dynamiccontent.innerHTML=java_message;}
      else if (document.getElementById)
            {rng = document.createRange();
             el = document.getElementById("dynamiccontent");
             rng.setStartBefore(el);
             htmlFrag = rng.createContextualFragment(java_message);
             while (el.hasChildNodes()) { el.removeChild(el.lastChild);  }
             el.appendChild(htmlFrag);
           }
    }
}
window.onload=altercontent
[/script]

 Method 9: Other Java Testers

 Retired:  Internet Explorer 6 and 7

This is just here for historical purposes. Maybe someday I'll update it for IE8, IE9 and IE10. Frankly, I have lost all interest in IE.

Advanced Options Tab

In Internet Explorer 6 and 7 do:   Tools => Internet Options => Advanced tab   and scroll down to about the middle of the options list. If a version of Java from Sun is installed, there will be a section in this list called "Java (Sun)". If Microsoft's Java is installed, there will be a section in this list called "Microsoft VM". If you see both, as the screen shot below (IE7 on Windows XP SP3) illustrates, then IE is using the one that is checked.

Sun Java Console

If a version of Sun's Java is installed, then do:   Tools => Sun Java Console.   In both IE6 and IE7 this opens a new window that says "Java console" in the blue stripe at the top of the window. The first two lines of the window display the version of Sun's Java, a sample is shown below. JRE means Java Runtime Environment.
NOTE: Sometime between Java 1.6.0_07 and 1.6.0_13 Internet Explorer 7 lost the Sun Java Console option under Tools on the menu bar (at least under Windows XP). The Java console is available by right clicking on the Java icon in the system tray/notification area.

Java Plug-in 1.6.0_07
Using JRE version 1.6.0_07 Java HotSpot(TM) Client VM

Three ActiveX Controls

Another IE specific approach is to check the version of the ActiveX control/program that implements Java.

With Internet Explorer 7 do:
  Tools => Internet Options => General tab => Browsing History Settings button => View Objects button
With Internet Explorer 6 do:
  Tools => Internet Options => General tab => Settings button => View Objects button

This takes you to the folder where the ActiveX controls live. In Windows XP (for both IE6 and IE7) it is:
  C:\Windows\Downloaded Program Files
At this point it gets messy.

The screen shot above is from IE7 on a Windows XP SP2 machine running Java 1.6.0_07.

1. Why are there three entries?
2. Why does each entry have two different version numbers?
3. How can anyone translate any of the displayed version numbers into 1.6.0_07?
4. Why do the two newer entries have yellow exclamation points?
5. Why is the Total Size for each zero?

You can right click on an ActiveX control and get its properties. For the most part, the properties display mirrors what you see above with two exceptions.

• Each ActiveX control has a "code base" and for each of the Java entries above the code base was
  http://java.sun.com/update/1.6.0/jinstall-1_6_0_07-windows-i586.cab
  Finally, a version number. You may feel like Indiana Jones at this point.
  
  
• Each ActiveX control also has a version description. The two entries above with the yellow exclamation points have a version description of "Java(TM) Platform SE binary". But the remaining entry above has a version description of "Java Plug-in 1.6.0_07 for Netscape Navigator (DLL" .

 Retired:   Java Console

The information here originally dated back to Internet Explorer 5 and 6, so it has been removed.

 Retired:   jview command

NOTE: This is very old. Microsoft got out of the JVM business long ago. Information on removing the Microsoft JVM is on the installing page.

For the Microsoft JVM, you can get information from the jview command when entered at a DOS prompt. If you receive an error that no program by that name exists, then there is no Microsoft JVM on your computer. If output is displayed, the first line will look something like this:

Microsoft (R) Command-line Loader for Java Version 5.00.3802

Microsoft confuses things in that there are two "versions" at play here. The   jview   command displays the version of the Microsoft JVM which is independent of the version of Java that it implements (1.1.4). This was, I believe, the point where Microsoft walked away from Java.

Versions of the Microsoft JVM are identified by build numbers. The first line of the jview output has a version number in x.yy.zzzz format. The final four digits (zzzz) are the version number. On a fairly untouched Windows 98 SE machine, the version was 5.00.3167. As of November 2002, the latest version of the Microsoft JVM was 5.00.3805 (see Scot Finnie's newsletter, October 11, 2002).  By December 2002, the latest version was 5.00.3809. As of April 2003, the latest version was 5.0.3810 and, as of July 2005, the latest version was still 3810. Microsoft Knowledge Base Article - 163637 INFO: Availability of Current Build of Microsoft VM has more on using the jview command.