JRE : Java Glossary

Introduction

To use the JRE you must be running W2K, XP, W2003, Vista, W2008, W7-32, W7-64, W8-32, W8-64, W2012, W10-32, W10-64, Linux, LinuxARM, LinuxX86, LinuxX64, Ubuntu, Solaris, SolarisSPARC, SolarisSPARC64, SolarisX86, SolarisX64 and OSX or Solaris.

• The last 1.7 JRE version was 1.7.0_79
• The current 1.8 JRE version is 1.8.0_131.

Which Java.exe?

When you install multiple JREs (Java Runtime Environments)and JDKs (Java Development Kits) you will have many different java.exe, javaw.exe, javaws.exe and javac.exe installed. Which one is used depends on which JREs and JDKs you have installed, which JVMs are enabled in the Java Control Panel, the SET JAVA_HOME, the path, the current directory and the phases of moon used in a pseudo random number generator to select one of the installed Javas. Verify you are using what you expect with java.exe -version.

Downloading the JRE

You can find the various downloads with your browser. For Vista, W2008, W7-32, W7-64, W8-32, W8-64, W2012, W10-32 and W10-64, make sure you are logged in as an administrator before you install. Some suggest it is best also to turn on UAC (User Account Control) (that irritating Visa User Account control) during the install. The downloads are labeled as updates, but they are complete in themselves. You don’t need to install a previous version.

Below is how to get Java for Windows, Linux and Solaris. For other platforms (e.g. various Unices) see your OS (Operating System) vendor’s site. For example for NetBSD Unix Java is included in pkgsrc (the Packages System).

A static JRE is one kept on an old version without upgrading it to test software on old the old version.

You might want to manually set your JAVA_HOME environment variable to the JRE directory e.g. C:\Program Files\java\jre1.8.0_131\. Some software finds Java using this variable rather than poking around in the registry. If you have a JDK at well set JAVA_HOME to point to it.

Polishing and Testing Your JRE

Testing your JRE is more complicated that you might expect. You want to find out if Java is working properly on the desktop and in each of your browsers. Further, you want to test that Java Web Start is working properly on the desktop and in each of your browsers. Just because Java/Java Web Start works in one browser, does not mean it will automatically work in another.

1. Click start ⇒ Control Panel ⇒ Java. Make sure all your JREs/JDKs are registered there. If not ask it to find and register them. Remove any JREs/JDKs you are not using.
2. Configure your set environment for the CLASSPATH. If you are not sure use CLASSPATH=. See environment for details of how. See classpath for details.

3. Copy your various library jars into the C:\Program Files\java\jre1.8.0_131\ \lib\ext\ directory.

   If you have Windows 7 64-bit, you will need to install two JRE s, a 64-bit one in C:\Program Files\java\jre1.8.0_131 for used by your desktop apps and by your 64-bit browsers and a 32-bit one in C:\Program Files (x86)\java\jre1.8.0_131 for use by your 32-bit browsers.

   Sooner or later you will have to reinstall the JDK/JRE and you will lose your ext directories. You can quickly rebuild them if you maintain a bat file like this and run it after every JRE/JDK install. Adjust the file to account for where your ext dirs are and where the jars are you need.

4. In Internet Explorer, go into Tools ⇒ Internet option ⇒ Advanced ⇒ Java(Oracle). Make sure Oracle Java is checked.
5. In Internet Explorer, make sure all three boxes under Tools Internet option ⇒ Advanced ⇒ Microsoft VM are checked.
6. In Internet Explorer 7+, you must OK allow blocked content permission to run Active X on the site, (even your own when running offline). This also gives permission to run Java. Since Java is perfectly safe because it runs it a sandbox, logically it should not need special permission. This roadblock to Java is just part of Microsoft’s war on Oracle and Java.
7. Test 

   java.exe -version

   You should see the expected version you just installed, probably 1.8.0_131. It can be problematic to have more than one version installed at a time.
8. Run Oracle’s formal Applet test of the Java JRE in a browser.
9. Test your JRE browser’s ability to run signed Applets by running Wassup.

   It should tell you that your browser is using the JVM version you just installed, probably 1.8.0_131. Look for the line marked java.version. If Wassup does not run, or you have the wrong version, go into Settings ⇒ Control Panel ⇒ Java Plug-In ⇒ Browser and turn off each browser, then click apply, then turn them on again, then hit apply again. Then retest with Wassup. If that still does not work, turn on the Java console, try Wassup again and look for clues.

10. Test Java Web Start on the desktop by typing javaws.exe and running any sample application.
11. Check that the associations for the *.jnlp extension is set to point to the appropriate javaws.exe and *.jar is set to point to javaw.exe.
    The associations for *.jar and *.jnlp are fragile. They mysteriously change to obsolete versions, or javaw.exe version without a console or even unrelated programs like Winzip.exe. Using the java.exe -jar myjar.jar syntax in your bat/btm files rather is more robust than myjar.jar. It works even when the associations are corrupted.
    Confirm this in any My Computer directory display with tools ⇒ folder options ⇒ file types.
12. Set up associations for *.jar files to make them double clickable, following the instructions to set up associations. By default the association will be set up to javaw.exe and you won’t see any output.
13. Check that Java Web Start is working in each browser by testing SetClock. Click SetClock to test.
14. Check the Opera browser’s quick preferences to make sure you have Java enabled. Turn on the console with tools ⇒ advanced ⇒ Java console to get some hints why it may not be working. Make sure Opera has *.jnlp files associated with mime type application-x-java-jnlp-file in preferences ⇒ files.
15. If you can’t get it to work, follow the failed install instructions.

Silent JRE Installs

Learning More

Linux

Android

Multiple JRE s

Then instead of saying java.exe, use the fully qualified name to select which version of the java run time you want e.g. C:\Program Files\java\jre1.8.0_131\ \bin\java.exe.