computer science

List of Java virtual machines

List of Java virtual machines is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand List of Java virtual machines rather than just read about it. In short: This article provides non-exhaustive lists of Java SE Java virtual machines (JVMs). It does not include every Java ME vendor.

Key takeaways

List of Java virtual machines belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect List of Java virtual machines to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of List of Java virtual machines from memory before moving on to harder problems.

Reference excerpt

This article provides non-exhaustive lists of Java SE Java virtual machines (JVMs). It does not include every Java ME vendor. Note that Jakarta EE runs on the standard Java SE JVM but that some vendors specialize in providing a modified JVM optimized for enterprise applications. Much Java development work takes place on Windows, Solaris, Linux, and FreeBSD, primarily with the Oracle JVMs. Note the further complication of different 32-bit/64-bit varieties. The primary Java VM reference implementation is the OpenJDK HotSpot, produced by Oracle Corporation and many other big and medium-sized companies (e.g. IBM, Redhat, Microsoft, Azul, SAP).

Free and open source implementations

Proprietary implementations

Active Azul Platform Prime – a fully compliant, high-performance Java virtual machine based on OpenJDK that uses Azul Systems's C4 garbage collector and Falcon JIT compiler. JamaicaVM (aicas) – a hard real-time Java VM for embedded systems.

Inactive Excelsior JET – a licensed Java SE implementation with AOT compiler for Windows, OS X, and Linux on Intel x86 and Linux on 32-bit ARM. Jinitiator – developed by Oracle before they purchased Sun. Designed to improve support for Oracle Forms in web sites. JRockit (originally from Appeal Virtual Machines) – acquired by Oracle for Linux, Windows and Solaris. Mac OS Runtime for Java (MRJ). Microsoft Java Virtual Machine – discontinued in 2001.

Lesser-known proprietary Java virtual machines Blackdown Java was a licensed port to Linux of the reference SunSoft implementation. It was discontinued in 2007, after OpenJDK became available. Sun CVM – CVM originally standing for "Compact Java Virtual Machine". Gemstone – modified for Java EE features (application DBMS). Intent (Tao Group). PreonVM– a Java VM for embedded systems and small and resource constrained devices.

Worked examples

Example 1 — a first encounter with List of Java virtual machines

Start with the simplest possible case. Write down what List of Java virtual machines claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to List of Java virtual machines before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about List of Java virtual machines ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of List of Java virtual machines

In research: List of Java virtual machines appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses List of Java virtual machines in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: List of Java virtual machines is common in secondary-school and first-year university syllabi. It links to neighbouring topics Java platform software, Java virtual machine, Lists of software, so understanding it makes those chapters shorter.
In everyday life: Look for List of Java virtual machines outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study List of Java virtual machines in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what List of Java virtual machines means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain List of Java virtual machines out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is List of Java virtual machines in simple terms?

This article provides non-exhaustive lists of Java SE Java virtual machines (JVMs). It does not include every Java ME vendor.

Why does List of Java virtual machines matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study List of Java virtual machines?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on List of Java virtual machines.