how to check jre version using java application

Question

i have made an application in JDK7, but the jre6 is still using in the market, and if i send my jar file to someone with jre6, it wont work, is there a way that application checks the jre version and if it doesn't compat then ask user to update..

Answer 1

You can use System.getProperty(String key); method with "java.version" as key.

String version = System.getProperty("java.version");

Example output:

1.6.0_30

The available keys can find at here.

Answer 2

System.getProperty("java.version")

• Demo

Note: It will return current jvm's version, jvm on which this code is executing, If you have java6 & java7 installed on your computer and you are running this code on java 7 it will show you version 7

Answer 3

static public void main(String[] arg) throws IOException
    {
        PrintStream out = System.out;
        Properties pro = System.getProperties();
        Set set = pro.entrySet();

       Iterator<Map.Entry<String , String >> itr = set.iterator();
        while(itr.hasNext())
        {
            Map.Entry ent = itr.next();
            out.println(ent.getKey() + " -> " + ent.getValue() + "\n");
        }
}

Use System.getProperty("java.version") or System.getProperty("java.runtime.version") to get installed version of java.
The above code snipped helps you find out more details such as java vendor name , OS etc.