What is the Android Native Development Kit (NDK)?

The NDK (Native Development Kit) is a tool that allows you to program in C/C++ for Android devices. It's intended to integrate with the SDK (it's described as a "companion tool") and used only for performance-critical portions of a project. See here for more information.

NDK may improve application performance. This is usually true for many processor-bound applications. Many multimedia applications and video games use native code for processor-intensive tasks. The performance improvements can come from three sources. Firstly, the native code is compiled to a binary code and run directly on OS, while Java code is translated into Java byte-code and interpreted by Dalvik Virtual Machine (VM). At Android 2.2 or higher, a Just-In-Time (JIT) compiler is added to Dalvik VM to analyze and optimize the Java byte-code while the program is running (for example, JIT can compile a part of the byte-code to binary code before its execution). But in many cases, native code still runs faster than Java code.

Java code is run by Dalvik VM on Android. Dalvik VM is specially designed for systems with constrained hardware resources (memory space, processor speed, and so on).

The second source for performance improvements at NDK is that native code allows developers to make use of some processor features that are not accessible at Android SDK, such as NEON, a Single Instruction Multiple Data (SIMD) technology, allowing multiple data elements to be processed in parallel. One particular coding task example is the color conversion for a video frame or a photo. Suppose we are to convert a photo of 1920x1280 pixels from the RGB color space to the YCbCr color space. The naive approach is to apply a conversion formula to every pixel (that is, over two million pixels). With NEON, we can process multiple pixels at one time to reduce the processing time.

The third aspect is that we can optimize the critical code at an assembly level, which is a common practice in desktop software development.

Disadvantage

NDK cannot access lots of APIs available in the Android SDK directly, and developing in NDK will always introduce extra complexity into your application.

The Android NDK is a companion tool used only in conjunction with Android SDK which allows application developers to build performance-critical portions of their apps by use of native (C/C++) code.

This provide benefits in form of reuse of existing code and increased speed.

Please go through below links.

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