Java is open-source, so what? [closed]_问答_开发者

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I always hear that Java being open-source is a big benefit, but I fail to see how Java being open-source should draw me to use it as opposed to .NET which is closed-source. This website has some Q&A sections (What is the significance of these developments to the industry? in particular) that give a little info, but is being free the only (or the biggest) advantage to Java being open-source?

Since I am a beginner, have any of you pros noticed any major difference since the change was made?

EDIT:

Please disregard the .NET part of this question, I was simply using it as a comparison. What I really care开发者_运维技巧 about is knowing what benefit becoming open-source has been to Java.

If you are a mainstream user, there is probably no immediate benefit for you.

However, the open-source base of Java makes it easier for people to adapt it to more niche requirements that the closed-source vendor sees no need to support. Smaller vendors (or open source projects) can come up with solutions to these special needs.

For example, Java runs on a great variety of platforms and operating systems, most of them supported by companies other than Sun (granted, that was the case even before it was open source).

have any of you pros noticed any major difference since the change was made

I like the fact that Linux distributions now include the "official" Sun JVM and JDK, rather than making you install it separately or use the "mostly-compatible" alternative implementation that was provided.

Not entirely fair to say .NET is closed source - Microsoft's .NET runtime and development tools are closed-source.

Mono is an open-source implementation of many things in the .NET world - the CLR and C# being the biggest.

The primary implementation of .NET is closed source, though there are competing open-source implementations.

The primary implementation of JVM is open source, though there are competing closed-source implementations.

The standard for Java remains entirely under control of Sun (Oracle). Others are allowed to provide input, but final decisions are up to Sun.

The standard for CLR is entirely under control of the ECMA and ISO. Microsoft is allowed to provide input, but the final decision is up to the standards bodies. If Microsoft did ignore their decision, it's open to question whether the standard would remain relevant.

The improvements to OpenJDK since it was open-sourced have been immeasurable, here is just a few:

The Zero project, contributed by Redhat, has ported Hotspot to many new platforms like PowerPC (32 and 64 bit), IA-64, ARM and zSeries, and made future ports to other platforms much easier. The Shark subproject has also given it better performance on some of those platforms
The OpenJDK has been ported to new operating systems, such as Haiku and BSD
Many bugs have been reported and fixed by individuals and companies
Apple has joined the OpenJDK project and a MacOS port is in the pipeline
So has IBM
Various innovative projects, such as IcedRobot have become possible
OpenJDK jtreg tests are now available to other Java implementations

Some of the direct benefits to the average Java programmer are:

You can investigate and fix bugs in the JDK source code
You can build custom versions of the OpenJDK (eg. strip it down to make it smaller)
You don't need to pay license fees to ship OpenJDK on embedded devices

Java and .Net are both standards for which anyone can write an open-source implementation. .Net 3.0 just happens to have no complete open-source implementations.

Regardless of openness, the difference for you (and the reason many people choose Java at all) is portability. There are far more implementations of Java, and most are closed.

Java can create apps for cell phones. Java can create web apps. Java runs on Mac. Not .Net.

Sun is just advertising the simplification and standardization which a common open-source core may provide. But if you look closely at the page you linked, you'll see that it's using the future tense.

Opening up the JVM source helps in porting it to other architectures such as ARM for embedded use.

More choices. Flexibility. Java Community Process. I think mainly lower cost of ownership - Eclipse+ApacheServer+Linux - are all free.