The difference between Android operating environment Dalvik mode and Art mode

Android system is built on the base of Linux system, the open-source Android system needs to be configured to different hardware configuration of the device, in order to reduce the development difficulty of the application, built a virtual machine called "Dalvik" on the Linux bottom, called the virtual machine, is actually an application of the compilation mode, Android4.4 began to introduce the art mode is a new application compilation mode, Android5.0 completely from Dalvik to art.

Dalvik mode:

Dalvik is Google's own Java Virtual machine designed for Android, and Dalvik virtual machine is one of the core components of the Android mobile device platform that Google and other vendors have partnered to develop. It can support the operation of a Java application that has been converted to. dex format, which is a compression format designed for Dalvik and is suitable for systems with limited memory and processor speed. Each Dalvik application executes as a standalone Linux process, allowing instances of multiple virtual machines to run concurrently in limited memory. A standalone process prevents all programs from shutting down when the virtual machine crashes.

Because Dalvik virtual machines, Android developers simply follow the SDK provided by Google to easily create apps, without worrying about hardware, underlying drivers and so on, each time the application is executed, the Dalvik virtual machine compiles the language of the program from the high-level language to the machine language. Dalvik relies on a just-in-time (JIT) compiler to interpret bytecode, each time the program needs to do the above, the bytecode compiled into machine language, so for a long time, the Dalvik virtual machine has been accused by the user to slow down the Android system running slower than the source of iOS.

Art mode:

The full name of the art model is Android Runtime, and Google has acquired a company called Flexycore, which has been working on the optimization of the Android system, and the art model has evolved in the company's optimization program.

When the art mode is enabled, the system will be pre-compiled when the app is installed, and the code will be converted to machine language to be stored locally when the application is installed, so running the program does not compile once every time and will improve execution efficiency.

Difference:

Compilation mode	RAM memory	ROM Memory	Fluid level	Power saving	Compatibility	Loading speed
Dalvik	Big	Small	Ordinary	Ordinary	Good	Slow
ART	Small	Big	Good	Good	needs to be optimized	Fast

The difference between Android operating environment Dalvik mode and Art mode