Question

I want to create a game for Android and I need to choose between SDK and NDK. Mobile phones have limited hardware and I want to avoid slowdown, but Java is slow and uses too much memory.

Are NDK apps faster and more efficient than SDK apps?

Java uses a garbage collector, all objects are allocated on heap, I cannot allocate an object inside another object (without a pointer), and a simple class that is used as a struct inherits the Object class.

Will my NDK program be converted into Java bytecode? Will the compiler ignore my delete calls, add garbage collector, add the Object class and transfer all of my objects to heap?

Answer 1

I’ll attempt to clear up some things:

• On Android, you always develop using the SDK. You can think of the NDK as a addon to the SDK. What the NDK does is allow you to develop native (e.g. C/C++) code in companion to your Java code (what you do on each side is up to you)
• Are NDK apps faster? Again, it depends on what you’re doing. Java can do a lot of things fast on devices with JIT especially. Well written C/C++ code is generally faster, yes. However, you also have to pay a penalty for going to and from Java/native (via JNI)
• If you look, there are game engines for Android written in the NDK. As of NDK r5 (and of course newer Android versions) you have the ability to draw to the screen from the NDK without first passing through Java/JNI which can give huge performance gains.
• No, your native code will absolutely not be converted to bytecode. It will be compiled as native ARM/MIPS/x86/whatever machine code.
• Unless you implement your own GC in native code, new, delete, etc. behave as normal. The Java VM doesn’t know anything about your native allocations unless you explicitly call JNI methods for creating new objects.