Shulou(Shulou.com)06/02 Report--

It is believed that many inexperienced people have no idea about how to configure the Dalvik virtual machine. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

Google officially released Android SDK at the end of 2007. As an important feature of Android system, Dalvik virtual machine has also entered people's field of vision for many times. Its efficient use of memory and its high performance on low-speed CPU are really impressive. Depending on the underlying Posix-compatible operating system, it can easily complete process isolation and thread management.

Each Android application corresponds to an independent Dalvik virtual machine instance at the bottom, and its code can be executed under the interpretation of the virtual machine. Many people think of the Dalvik virtual machine as a Java virtual machine. Because the programming language of Android is precisely Java. But this is not accurate because the Dalvik virtual machine is not implemented according to the specification of the Java virtual machine, and the two are not compatible; there are two obvious differences:

The Java virtual machine runs Java bytecode, while the Dalvik virtual machine runs its proprietary file format, DEX (Dalvik Executable).

Java classes in Java SE programs are compiled into one or more bytecode files (.class) and packaged into JAR files.

Then the Java virtual machine obtains the corresponding bytecode from the corresponding CLASS file and JAR file; although the Android application is also programmed in the Java language, it is compiled into a CLASS file. It also converts all CLASS files of the application into a DEX file through a tool (dx), from which the Dalvik virtual machine reads instructions and data.

As shown in the figure, the Android runtime consists of two parts: the core library and the Dalvik virtual machine. The core library includes the most basic class libraries, such as data structure, network, Utilities, File system and so on. A lot of the implementation code comes from the Apache Harmony project, and the main purpose is to ensure that the virtual machine's class library is compatible with the Java SE's class library.

So as to reduce the difficulty of the transfer of application developers from the Java SE camp to the Android development camp and increase their availability. Dalvik virtual machine mainly completes the important functions such as object life cycle management, stack management, thread management, security and exception management, garbage collection and so on.

As shown in the figure, the Android runtime consists of two parts: the core library and the Dalvik virtual machine. The core library includes the most basic class libraries, such as data structure, network, Utilities, File system, etc., and much of the implementation code comes from Apache Harmony projects.

The main purpose is to ensure that the virtual machine class library can be compatible with the Java SE class library, so as to reduce the difficulty for application developers to transfer from the Java SE camp to the Android development camp and increase its availability. Dalvik virtual machine mainly completes the important functions such as object life cycle management, stack management, thread management, security and exception management, garbage collection and so on.

After reading the above, have you mastered how to configure the Dalvik virtual machine? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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