Question: Why J2EE why not J7EE or J8EE . We got latest version as Java 8. But, why still, it is being Java Platform 2 ? What is a significance of "2" here ? Or It looks good, that's why they never changed its name or some other reason ?

Answer: 
Java enterprise edition was introduced around the time of Java 2 (which was rebranded from Java 1.2). As part of the branding they included the numeral (originally). Now it is officially [Java EE](http://docs.oracle.com/javaee/7/index.html) (withtout the numeral 2).
There is a good explanation of that in the link below :
[[Java EE vs J2EE vs Jakarta EE]](https://www.baeldung.com/java-enterprise-evolution)

***For J2EE :***

In the first version of Java, Java enterprise extensions were simply a part of the core JDK.

Then, as part of Java 2 in 1999, these extensions were broken out of the standard binaries, and J2EE, or Java 2 Platform Enterprise Edition, was born. It would keep that name until 2006.

For Java 5 in 2006, J2EE was renamed to Java EE or Java Platform Enterprise Edition. That name would stick all the way to September 2017.