A Java virtual machine (JVM) is a virtual machine that can execute Java bytecode. It is the code execution component of the Java platform.

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Is it possible to implement a native compiler for a 'managed language' such as Java?

In most cases, it is possible to create both a native compiler and an interpreter for a programming language. The compiler would simply convert the source code to machine code, and the interpreter ...
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0answers
232 views

Detecting when flow of control has shifted to native thread in java

For an arbitrary Java program for which I have full access to the source code but I cannot re-write per se, (instrumentation is permitted) how can I tell when a java thread has called into a native ...
2
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6answers
452 views

Is Java Bytecode interpreted? [closed]

The definition of interpretation (correct me if I'm wrong) is parsing code like so: 1- Translate currently parsed line to some intermediate language. 2- Run the translated line. 3- Move to the next ...
3
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5answers
540 views

What exactly is the Garbage Collector in Java?

I think I generally know what the Garbage Collector in Java does, but It's praised a lot, so I thought maybe I'm missing something about it's functionality. What I know is, that the GC takes care of ...
2
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2answers
223 views

What is the advantage of a programmers VM apart from portability [duplicate]

I can understand the benefits of Java running on a JVM. Portability. Nice simple reason. But I have always been puzzled as to why Microsoft brought out their own version of a JVM - .NET. C# is ...
5
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1answer
221 views

What would be the market life of a JVM based software framework?

I saw how Struts 1 lasted from 2000 to 2013. I hear that people are moving from Struts 2 to Spring. But for a project that may need to be maintained for a decade or two, would it be advisable to opt ...
2
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1answer
502 views

How to create own programming language based on JVM? [closed]

I am curious about how to create a programming language based on JVM so I have tried to get some info online, but the information I got are quite fragmented. What I found are mostly information ...
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2answers
2k views

Is it *ever* okay to catch StackOverflowError in Java?

I used to think that it's not, but yesterday I had to do it. It's an application that uses Akka (an actor system implementation for the JVM) to process asynchronous jobs. One of the actors performs ...
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3answers
184 views

Java Compiler and VM Compatibility

A co-worker and I recently had a discussion about Java versions and the JVM. I use Java 7 but we use Java 6 for our client (while he says that some are still on 5). My immediate thought was, why can't ...
12
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5answers
905 views

What makes JVM so much versatile to support so many JVM languages?

JVM supports so many languages other than Java like Groovy,Clojure,Scala etc which are functional languages unlike Java(I am referring to Java before Version 8 where Lambda's are not supported) that ...
4
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2answers
251 views

How are Scala Traits implemented in the JVM?

I have been reading about traits in Scala. They are pretty amazing. I am curious how they extend a class without actually resulting in multiple inheritance. I know that the JVM doesn't support ...
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2answers
374 views

JVM vs operating systems [closed]

Recently i was re-visiting the basic concepts of operating systems. Since I am a java developer, I have inherently started looking at everything from java point of view. I am also reading 'Inside the ...
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5answers
500 views

Java heap space

In Java/JVM, why do we call the memory place where Java creates objects as "Heap"? Does it use the Heap Data Structure to create/remove/maintain the objects? As I read in the documentation of Heap ...
4
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1answer
359 views

Does current JIT optimize generated machine codes for branch prediction based on runtime statistics?

Some JVMs would compile Java byte code into native machine code. We know that there are lots of optimizations we could apply for that. Recently, I also learn that a branch operation may block the CPU ...
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4answers
3k views

What limitations does the JVM impose on tail-call optimization

Clojure does not perform tail call optimization on its own: when you have a tail recursive function and you want to have it optimized, you have to use the special form recur. Similarly, if you have ...
1
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3answers
172 views

Java Terms that are Plagued with Vaguery [closed]

What's the difference between a Java Process (what your OS sees) and a JVM? Are they one in the same or are they actually different? How are the JRE and JDK different (in purpose and file content), ...
2
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2answers
319 views

How to devise instruction set of a stack based machine?

Stack based virtual machines like CLR and JVM has different set of instructions. Is there any theory behind devising the instruction set while creating a virtual machine? e.g. there are JVM ...
8
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4answers
2k views

How does the Java Virtual Machine execute code written in other languages?

Since Java 1.6 the JVM can run a myriad of programming languages on top of instead of just Java. I conceptually understand how Java is run on the Java VM, but not how other languages can run on it as ...
12
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1answer
1k views

How can Java be improved so that it no longer needs to perform type erasure?

The official Java tutorial on generics explains type erasure and why it was added to the compiler: When a generic type is instantiated, the compiler translates those types by a technique called ...
11
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4answers
2k views

Approaching Java/JVM internals

I've programmed in Java for about 8 years and I know the language quite well as a developer, but my goal is to deepen my knowledge of the internals. I've taken undergraduate courses in PL design, but ...
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2answers
640 views

Converting ANTLR AST to Java bytecode using ASM

I am currently trying to write my own compiler, targeting the JVM. I have completed the parsing step using Java classes generated by ANTLR, and have an AST of the source code to work from (An ANTLR ...
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4answers
505 views

Static methods on a web context

What happens when concurrent requests call the same static Java method running on an application server? Say that a method run takes 2 seconds and receives 100 calls in a given second. The method ...
3
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1answer
131 views

What is richochet frames based hotspot jvm?

In order to implement JSR 292, a.k.a. invoke dynamic, something called richochet frames is introduced into the hotspot vm. I'd like to know more about it, such as invoke dynamic itself, how richochet ...
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5answers
470 views

Modern languages and the JVM

Many modern programming languages (Scala, Erlang, Clojure, etc.) are targeting the JVM. What are the main reasons behind that decision? JVM's maturity? Portability? Because JVM simply exists, and ...
3
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1answer
245 views

Incanter for real world statistical projects

I'm interested in statistical computing. R is a leader platform obviously but what about Incanter? Incanter is at the top of my list since I'm a Clojure and JVM guy. Do you have any real world ...
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3answers
588 views

How safe it is to do minor JVM upgrades?

I have been working on the JVM for years and I have very rarely experienced a JVM crash ... that is until approx 6 months ago. Since that I have experienced approximately 5 JVM crashes resulting ...
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4answers
3k views

Is Clojure, Scala and other restrained by the JVM vs CLR

The Java implementors seem slow to adopt language improvements, for example compare C# with full closures, expression trees, LINQ etc.. to Java, and even the push back of some stuff to Java 8 will ...
4
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3answers
308 views

How do I get feedback about whether escape analysis had any affect on my code or not?

One problem I have with compiler optimization is, that I actually never know what the compiler (or in this particular case the Jit) does with my code. So is there any possibility for me to know ...
10
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2answers
940 views

Java and JVM license

Does Java license allow other companies to create their own versions of Java language or just implement it accurately? Same question about JVM. I heard about Sun suing Microsoft for changing their ...
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5answers
3k views

Is there a clear leader amongst JVM-based languages? [closed]

What is the current status of these projects, and has any one (or two) emerged as a clear leader? To demonstrate my motives for asking this question, cast your mind back several years. Prototype and ...
3
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4answers
577 views

How to disseminate Scala?

With the announcement of Ceylon, and after observing the slides describing its intent and feature list, I reckoned this language to be a Scala competitor. Furthermore, as a Scala programmer, I can ...
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3answers
2k views

What is the difference between instantiating and loading a class in Java?

In Java world, there are some scenarios where I see developers used to load the class rather than instantiation. What is the difference between instantiating and loading a class?
5
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10answers
358 views

Does your workplace allow the use of multiple, interoperable programming languages?

Since now there are several good languages that target the JVM and can interop with Java with varying degrees of painlessness, and likewise for the CLR (especially with the recent addition of F# as an ...
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4answers
2k views

What is the best JVM Lisp for writing a video game? [closed]

This video game won't be super fancy, but the idea is for it to have a moderate amount of functionality. Thoughts? Edit: Fast would be nice. Another edit: This is what I want: To be able to ...
5
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9answers
593 views

Is there any evidence that one of the current alternate JVM languages might catch on?

There's been a lot of enthusiasm about JRuby, Jython, Groovy, and now Scala and Clojure as the language to be the successor to Java on the JVM. But currently only Groovy and Scala are in the TIOBE ...
9
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5answers
469 views

How is the JVM and Java's WORA different from other high level languages?

In the Java world, we often talk about the JVM, and when Java was new it had the supposedly killer feature of "Write Once, Run Anywhere." From the way people talk and write, this seems different from ...
10
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3answers
458 views

Is Apple getting out of the general purpose development platform business?

I've been doing general ANSI C/Console C++/Java/Web development on Mac hardware for about ten years. I make no claims of objective superiority over other platforms, it just satisfies my personal ...
5
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3answers
3k views

Jython and JRuby vs. Groovy (and Java) [closed]

I am very interested in Python for programming on the JVM, and I've worked in Java and Ruby (not JRuby) a lot, and to a certain extent in Groovy. What are the limits to the Java-Jython and Java-JRuby ...