Android中dalvik和传统java虚拟机的区别

What’s a Dalvik?

Dalvik is a virtual machine (VM) designed and written by Dan
Bornstein at Google. Your code gets compiled into machineindependent
instructions called bytecodes, which are then
executed by the Dalvik VM on the mobile device.
Although the bytecode formats are a little different, Dalvik is
essentially a Java virtual machine optimized for low memory
requirements. It allowsmultiple VMinstances to run at once and
takes advantage of the underlying operating system (Linux) for
security and process isolation.
Bornstein named Dalvik after a fishing village in Iceland where
some of his ancestors lived.

The Dalvik VM is Google’s implementation of Java, optimized for mobile
devices. All the code you write for Android will be written in Java and
run within the VM.
Dalvik differs from traditional Java in two important ways:
• The Dalvik VM runs .dex files, which are converted at compile time
from standard .class and .jar files. .dex files are more compact and
efficient than class files, an important consideration for the limited
memory and battery-powered devices that Android targets.
• The core Java libraries that come with Android are different from
both the Java Standard Edition (Java SE) libraries and the Java
Mobile Edition (Java ME) libraries. There is a substantial amount
of overlap, however.

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