Running multiple versions of Java on the same Windows machine 10/8/7

Running multiple versions of Java on the same Windows machine 10/8/7

Many times we have to run two or three or several version of java jre, jdk  in windows machine.

For the purpose of run java based software we need to set our windows machine environment.

Order of Java Installations

First of all, the order install Java Runtime Environments(JRE). Install the JREs from oldest to newest in that order and verify the newest version like 8. If you install the JREs out of order, it is best to simply remove all Java installations, restart the machine, and install them from oldest to newest. This procedure is help to recognize multiple Java versions correctly.

Java Installations location

Each Java installation gets installed at:

C:\Program Files\Java\jreX

Where is X represents the Java  version . So if you have Java 6 and Java 8 installed you will have to directories.

Java Browser Plugin

If your application runs in a web browser using Java's browser plugin, you can only have one version at a time. Ignition does not use Java's browser plugin so you can continue using an older version. On your web browser like internet explorer need to configure active x control and check all security option and enable disable as based on your requirement.

Running Existing Java Application

To do this we need to set the Windows PATH variable to the correct version of Java. To find out which version is on the path right now simply do the following procedure.

Open Command Prompt by pressing Start Key + R. Type cmd and press Enter.

1. Type "java -version" and press Enter.
2. You will see which version of Java is currently on the path. It will start with 1.X.X, so if it is 1.7.0_05 it is Java 7.

You will find either that no Java version is on the path or you will know which version is currently on the path. If the version found is the version required by your existing application you can skip down to opening Ignition's client. If not, we need to change the Windows PATH variable to put the correct Java version. Follow these steps:

1. Open the Environment Variables window. Open File Explorer (Start Key + E). Right click on "My Computer" and select "Properties". Click "Advanced system settings". Click on the "Environment Variables" button in the
   "Advanced" tab.
   
   
2. Find the Path variable in System Variables and click "Edit...".
   
   
3. Now you need to add the path to your Java version that your existing application uses. You need to make sure it points to the bin folder for your Java version. It should look something like:
   
   C:\Program Files\Java\jre1.6.0_01\bin
   
   Make sure to separate the path locations with a semi-colon (;).
   
   **NOTE** : The windows installer's for Java puts java.exe in your System32 folder so that you can run Java without setting environment variables. When adding "C:\Path\to\your\Java\version\bin" to your PATH make sure that it appears before C:\Windows\System32. Also make sure a different path to Java doesn't appear before your addition.
4. Once you have added the correct version to the Windows PATH, type "java -version" in the Command Prompt to verify.

Running Ignition Client

Ignition will try to use the correct version of Java automatically using the native client launcher. You don't want to use Java Web Start since you may have to change a few settings to get it to work. To use the native client launcher simply follow the steps below:

1. Open the Ignition Gateway home page in your web browser (http://IPADDRESS:8088)
2. Download and run the Windows client launcher.
   
   
3. Enter in your Ignition Gateway URL on the "Manually Input Gateway" tab and press Apply. Then press "Continue" at the bottom.
   
   
   
4. Launch your project and it will find the correct version of Java for you.

That is it! It is very possible to run multiple versions of Java on the same machine so you can run your existing applications and Ignition at the same time. You just need to make sure a few house keeping items are taken care of. If you have any questions or are experiencing any issues please contact our tech support.