How to find all the jre's installed on desktop

Question

I have installed JRE131, 142, 150 on my destop. How do I find out all these JRE versions using a Java Program or JavaScript?
Thanks in advance

Answer 1

Let me explain my question again.
We have "java applications" written to run with JRE 1.3.1, 1.4.2 and 1.5 (default JRE - higher version) etc, we are trying to access these applications using java web start. As we know that Java web start has an in-built capability to find required JRE installed on the remote PC(Using Native library). If the required JRE is not installed on remote PC, then the JNLP will make call to java.sun.com/autodl to download 1.2 version of JRE which we don't want that to happen(bcos of internal policy), rather we would like to determine whether or not this JRE is already exist on the remote client from the browser where the below JNLP is called to invoke the application. I do know that we dont have direct ability to check the JRE existence except default JRE(ie higher version among installed JREs, In here JRE 1.5 as mentioned above) using java/javascript. Take a look at the below applet code which would return only current jre version as if 1.3.1 and 1.4.2 are not installed although they exist. What I'm trying to do now is to populate a message on the IE browser itself to remote user saying that this 1.2 JRE is not installed, so please install it before calling below JNLP. So, How do I find out all the JREs installed on PC not just default JRE? I hope the question now is clear
Thanks thanks....
<?xml version="1.0" encoding="UTF-8"?>
<!-- file Hello.jnlp -->
<jnlp codebase="http://staff.develop.com/halloway/TechTips/May2001"
href="http://staff.develop.com/halloway/TechTips/May2001/Hello.jnlp">
<information>
<title>Hello</title>
<vendor>Tech Tips Sample May 2001</vendor>
<icon href="HelloJNLP.jpg"/>
</information>
<resources>
<j2se version="1.3"/>
<jar href="HelloJNLP.jar"/> --- This is the Java Application and will run on remote client using java web start
</resources>
<application-desc main-class="HelloJNLP"/>
</jnlp>
import java.applet.Applet;
import java.awt.Label;
public class Detect extends Applet
public Detect()
public void init()
add(new Label("Detection of the Java Plugin"));
public String getJavaVersion()
return System.getProperty("java.version");
//return System.getProperty("java.specification.version");
}