Member Avatar for gunbuster363

What is java and the whole bunch of things.
I only know how to use eclipse to write java project, probably java 1.4.

Can someone give me a picture about the whole bunch of java things such as jsp servlet spring struts hibernate J2EE glassfish J2EE 5 J2EE 6 EJB bah bah bah...


Someone said a programmer who know J2EE worth quite a lot of money, but there can I start to learn about it? I don't even know will the company use the lastest update of J2EE, maybe some of them are still using version that is quite old.

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  • Latest Post Latest Post by stultuske

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A short, practical map of the Java ecosystem and a clear path forward.

Java is best thought of in layers: the language and core libraries (Java SE), the runtime/build tools (JVM, JRE, JDK), and the enterprise/web APIs (historically Java EE, now maintained as Jakarta EE). The JVM executes bytecode, the JRE bundles a JVM and runtime libraries, and the JDK adds the compiler and developer tools. Legacy version names caused confusion (for example, 1.5 is the same release marketed as Java 5), so focus on feature sets rather than the exact marketing label.

A sensible learning order for someone with Eclipse experience but limited core knowledge:

  • Master Java SE fundamentals: syntax, object orientation, collections, exceptions, generics and basic concurrency.
  • Learn essential tooling: Git, a build tool (Maven or Gradle), and unit testing (JUnit). Use a modern LTS JDK for practice (for example Java 17 or Java 21).
  • Once comfortable, add web fundamentals: HTTP, the servlet request/response model and JDBC. Knowing servlets gives insight into what web frameworks abstract away.

For enterprise work, frameworks and servers matter: frameworks like Spring (widespread in industry) and persistence via JPA implementations such as Hibernate are the common stack today; application servers (GlassFish, WildFly) implement Jakarta EE specs, while servlet containers (Tomcat) handle servlet/JSP parts. Many companies run older platform versions, so focus on concepts and transferable skills rather than a single minor release.

Concrete immediate steps: complete one console project, one small JDBC CRUD app, then a minimal web app (either a plain servlet on Tomcat or a Spring Boot app). Reference material: Oracle Java Tutorials, Jakarta EE homepage, and Spring Boot docs. This echoes : firm up the basics before diving into higher-level frameworks.

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Member Avatar for gunbuster363

I have googled about java ee before and I am so confused.
Someone in a forum thread said the company are not ready to upgrade to java ee 5 or even 6, they are still using java ee 1.4

And the whole bunch of numbering of java sdk jdk ee se 1.4 1.5 5 6 also confused me.


Should head into learning some servlet things?

Member Avatar for stultuske

even as a junior programmer, you should know that software comes in different versions.
just take a look at http://java.sun.com, which should be your first source on getting to know Java, all the things you are asking about are very well explained there.

should you go ahead and learn servlets? no.
since it's clear you have no knowledge of the basics of Java, why would you try more dificult tasks?

If you try without understanding the basics, you'll propably learn yourself a working yet inefficiënt way to develop servlets, so start with the syntaxis and some basic training material first. First learn to crawl, than to walk, don't expect you'll be running a marathon before you have taken your first steps.

to get back at this:

Someone said a programmer who know J2EE worth quite a lot of money, but there can I start to learn about it? I don't even know will the company use the lastest update of J2EE, maybe some of them are still using version that is quite old.

if earning money is your only motivation, and you just take this career because "someone said" such developers are worth a lot of money (doesn't mean that developer gets paid a lot himself, by the way), you may want to look into what you really want to do with your life.
secondly: how on earth can we know what your company is using? not only does this depend from company to company, but even within a company, it is very well possible that different teams use different versions. Not to mention the number of companies that don't use Java at all.

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