Is it possible? Runtime Questions

**Andrew R** · August 11th, 2013, 12:19 AM

Hey guys,

I am still not a pro with Java but my imagination isn't bad at all. I know with Java I could "be God" and do whatever I want, just that I need to learn to be able to get there. Even so, I still would like to ask you fellas a couple of questions, and probably get a hint or two on how to get to what I am trying to accomplish.

You know, the JVM jumps from class to class when we let it know she need to look for the code elsewhere. I've been working on a project of main classes creating other main classes. The good thing about them is that they are independent from from another if I make sure its that way.

1) Is it possible for the runtime to jump from one program to the other, without ever having to go back to the original main class?
In other words, I am asking if there is some sort of "break" operator, that enables the runtime to completely divorce from the original, stopping without ever going to the last part of the code of first main class.

2) Is it possible to have 2 or more runtimes, which originated from one Runtime?
We are still talking about independent classes creating and starting other classes.

3) If question #2 is a "Yes", how many Runtimes could the JVM or equipment would be able to handle?
For example, how many 10kb - sized main classes could run simultaneously, without having the JVM ask for mercy, or the rest of the equipment.

4) Classes are compiled in the native byte code. Is it possible to convert class files into a different programming language?
This is a logic question, since we know that byte code is the native language, some kind of "international" convention or converging point to other languages.

**helloworld922** · August 11th, 2013, 01:13 AM

1. Classes aren't executed, functions/methods and statements are executed. You can pop up multiple frames on the call stack by using exceptions, but the preferred method is to introduce logic in the calling code which will return normally. There are a few other minor special cases, but these should be avoided whenever possible. There is no goto statement in Java (despite there being a goto keyword in Java, there are historical reasons for this).

2. Each runtime is a separate process execution. In general an application isn't multi-process, rather they are multi-thread. This has multiple paths of execution which can run concurrently on a single process/runtime.

3. You can have as many processes as your system/OS allows.

4. Java byte-code is not assembly/machine code. That's both a benefit and disadvantage of Java byte-code. The process of converting a lower-level output code to a higher-level format is de-compiling. Java byte-code preserves (or can preserve) a surprising amount of information, so it's relatively easy to de-compile Java byte code back to Java. Note that even if you de-compile back to Java, you're not guaranteed to get back your original source because comments will be lost. I'm unsure what level of optimization different Java compilers use to get to byte-code, but if any optimizations are done you can get some really different output, with the only guarantee that the output be that the output will have no noticeably different results.

De-compiling Java byte-code, or even just converting Java code to another language may be possible, but I have my doubts. The main problem is the Java standard library, which may have no direct equivalent in another language. Basically, good luck getting this working for the vast majority of programs.

**Andrew R** · August 11th, 2013, 01:25 AM

Hey great answers overall.

I am just not to happy with your first answer -that was straight from the book. Probably I did't get my objective clear with these questions.
I know about calling code. And Yes we can technically call cmd prompt to complie and execute another main class. I am certainly interested in these "minor special cases" because the whole idea of executing class files technically not dependent of the original one has a purpose to it.

Is there anything you like to hint me? I would appreaciate.

**helloworld922** · August 11th, 2013, 02:34 AM

You can't "jump" into another process. The closest you get is start another process and forcibly terminate your current process. I have no idea why you would want to forcibly terminate your current process just because you started another process, though. Your process shouldn't terminate suddenly unless something horribly wrong has happened.

What are you trying to do? There may be a better way to accomplish the same goal without using some very unsafe code.

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