Is a Dalvik virtual machine instance created for each application?

Every Android application runs in its own process, with its own instance of the Dalvik virtual machine. Dalvik has been written so that a device can run multiple VMs efficiently.

The Dalvik VM executes files in the Dalvik Executable (.dex) format which is optimised for minimal memory footprint.

The VM is register-based, and runs classes compiled by a Java language compiler that have been transformed into the .dex format by the included dx tool.

Also have a look at What is... The Dalvik Virtual Machine for detailed description about DVM.

1. The Dalvik virtual machine is built specifically for Android. It was built to address the battery life and processing power problems, and it is free.

2. We are using Dalvik VM instead of Java Virtual Machine (JVM) because the Java compiler, the Java tools are free, but the JVM is not free, so the Android developers from Google have made their own virtual machine, and made it as free.

3. A virtual machine is necessary because the virtual machine helps in debugging, as a virtual computer so that my applications can run different devices the same way

Pictorial Representation

A .java file is given to the java compiler (javac) to generate the .class file.

All .class files are given to dx tool to generate a single dex file.

The dex file is given to the Dalvik VM to generate the final machine code.

The final machine code is given to the CPU to execute.