Your post is somewhat uninformed for a number of reasons: - this isn't an official Google forum for Android. - there are other more appropriate places for your question: android-platform, for example - Being able to build a computer == being able to modify a 50 million line operating system? Sorry, I don't see that comparison. - why Java? Fits the VM architectural model. - Dalvik doesn't obviate the security architecture of the linux kernel, it works together with it. Most of the security benefits in Android are *indeed* from linux itself! - You seem to think that the VM is slow. This is a common claim, but do you really know? Dalvik as an interpreter was pretty damn good, when it got JIT capabilities it became even faster, so much of the code executing *is* native code. - The fact that the NDK exists is an indication that Java isn't the best? What are you talking about? Every successful high level language has a way to talk to lower level code: Haskell, OCaml, etc.., Does that mean it's slow / wrong? No, it just means that sometimes you need a lower level of control you can't get from the langauge. Am I saying that Dalvik will kill it for custom graphics code? No, but that's why the NDK exists: to handle the very small percent of times when you *really do* need native code that controls low level hardware. - The cross platform decision wasn't really the sole reason Android settled on Java, I would wager it was the fact that it is simpler to write in than C++, just my blind guess. - The OS isn't implemented on Java, much of the higher level stuff is, and lots of time is actually spent in systems level code anyway... - Unsure if you were around, but the NDK isn't new, it's been around since Java :-)
The architect surrounding the VM and the choice of Java isn't specific. In fact, calling it a *Java* virtual machine is just plain wrong. What runs on Android is Dalvik bytecode. It's not quite the same, it's a register rather than stack based virtual machine, and there are some other differences as well. The way the VM is built allows the platform to be architected a certain way, via forking a zygote process and getting tons of common memory. You're asking some questions that seem to imply Android is *bad*, but you don't really have much support for those claims. Certainly Android is *different* than Objective C, but the claims as to why it's "worse" are somewhat unfounded here... This video is old, but still relevant to help clear up some of your confusion: http://www.youtube.com/watch?v=ptjedOZEXPM And remember, this forum isn't for discussion of the OS design, and Google employees probably won't answer you :-). You could try android-platform, but I'd think about these points before you reask your question! kris On Fri, Sep 14, 2012 at 9:11 PM, jamb <[email protected]> wrote: > Hello Android devs! > > I recently bought a Motorola Razr Maxx, and then shortly after an Asus > Transformer Infinity TF700T.... I suppose it goes without saying that I like > the idea behind Android as an OS. But I'm a little curious about the > architecture decisions, and thought this would be the best place to ask.... > As far as I know this is the only "official" Google forum for Android OS. > > As someone who has always built my own PCs from scratch, I have a pretty > decent idea about hardware architecture. While I run Windows as my main OS, > I've experimented with Linux and BSD on occasion (with mixed and often > disappointing results, due to the hardware I choose). I'm no stranger to > digging into the OS and tweaking as I see fit. So after grabbing the Android > SDK and digging more into the architecture, one huge question is baffling > me.... > > Why Java? > > If my understanding of Apple products is accurate, iOS is based on FreeBSD > with Apple specific hardware drivers and Cocoa. It's my understanding that > Cocoa is a native set of classes that function in a similar way as GTK+ or > QT, but developed "in-house" at Apple. > > So why did Google choose to implement Android as a barebones Linux Kernel, > with phone/tablet specific drivers and a Java VM? Linux already has a > fantastic security model, which (in my opinion) reduces the benefit of a > sandboxed (virtual machine) environment. And a virtual machine, by > definition cannot possibly perform as well as native code - even if it IS a > hand optimized version. > > In deciding to use Java as it's primary application architecture, it appears > to me that Google crippled Android from the get go. The fact that the NDK > exists at all is a good indication that Java was not the ideal solution. > > C/C++ has always been a relatively robust language to design cross-platform > applications - with some effort and preprocessor directives. Java is > definitely _more_ portable, but who uses Android apps, but Android users? I > just don't see that Java was the best way to implement an OS. Embedded > developers design software for 2 platforms: iOS and Android. Using Java as > the primary architecture forces developers to do far more than include > different preprocessor directives and libraries - apps have to be redesigned > from the start, even using NDK. In fact NDK is kind of a joke - using a VM > to execute native code within it's context - of course there's no > performance increase, though there's a huge increase in complexity! > > So why didn't Google choose a similar route as Apple? Creating a framework > like Cocoa based on a Linux kernel (and using native c/c++ code)? > > If I'm off in left left or simply missing some major point, I'm more than > happy to learn! > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
