Dalvik Virtual Machine in Android

 Dalvik Virtual Machine in Android

Dalvik Virtual Machine:- 

Dalvik Virtual Machine is used to execute the applications that written for Android. Dalvik was an integral part of the Android software. Dalvik is a Open Source Software this is originally written by the  Dan Bornstein and Dalvik name is given of a town in Iceland .

Dalvik like as Java Virtual Machine. This is used for mobile device, Tablets and wearable device and TV etc. Dalvik program written in Java using the Android Application programming interface, Compiled into Java bytecode and which is translate into Dalvik bytecode and stored in .dex (Dalvik Executable) and .odex (Optimized Dalvik Executable) files. These files stored bytecode. Java bytecode is also converted into an alternative instruction set used by the Dalvik VM. An uncompressed .dex file this file smaller then JAR file. 

Characteristics of Dalvik:- 

1. The Virtual Machine was slimmed down to use less space.

2. The constant pool has been modified to use only 32-bit indices to simplify the interpreter.

3. Standard Java bytecode executes 8-bit stack instructions. Local variables must be copied to or from the operand stack by separate instructions. Dalvik instead uses its own 16-bit instruction set that works directly on local variables. The local variable is commonly picked by a 4-bit "virtual register" field. This lowers Dalvik's instruction count and raises its interpreter speed.