Java language overview of Java Basics

Java language is a high-level programming language launched by sun (Stanford University network, Stanford University network company) in 1995. At first, it was mainly used in small consumer electronics products. Later, with the rise of the Internet, Java language rose rapidly (Java applets can run in browsers) and became the preferred language for large-scale Internet projects.

On April 20, 2009, Oracle acquired sun for $7.4 billion and obtained the copyright of Java.

Java is an object-oriented language. Readers without object-oriented programming experience need to spend a lot of time to understand the concept, syntax and programming ideas of object-oriented. If you can't understand something, please insist. Spending more time writing code will naturally be suddenly enlightened. It needs an adaptation period from process-oriented to face object.

Java is not just a programming language. It is a complete platform with a huge library, which simplifies complex operations such as graphics rendering, socket connection, database access and so on to the greatest extent.

Java is cross platform, compiled once and running everywhere. The code written on windows can be transplanted to Linux without modification, and vice versa.

In the world programming language ranking, Java almost occupies the second place, second only to C language.

Java is a typical object-oriented language, which was released later than C + +. Some syntax and ideas also refer to C + +. See the following table:

Although people find that the syntax of C + + is too complex and redundant, Java is still as close to C + + as possible in design to reduce people's learning cost. Java syntax is a "pure" version of C + + syntax. It has no header file, pointer operation (nor pointer syntax), structure, union, operator overload, virtual base class, etc. readers with C + + foundation can easily switch to Java.

Java is widely used:

1. Web development: Java is very suitable for developing large enterprise websites, such as Renren and qunar. 2. Android Development: almost all apps on Android phones are developed in Java, such as QQ, wechat and UC browser. 3. Client development: Java can also be used to develop software on computers, such as elipse and NetBeans. 4. Embedded application: embedded application is the software running in small electronic products, such as the software on old mobile phones and MP3.

However, I can responsibly tell you that the main application directions of Java are web development and Android development, and most Java programmers recruited by IT companies are also engaged in these two aspects.

The GUI Library of Java is not excellent, and many users are not used to its interface; The client written in Java consumes more resources; More importantly, Java programs can only run with the help of virtual machines. The operating system does not install virtual machines by default (which will be described in detail in the next section). Few client programs for ordinary users are developed in Java.

In the embedded aspect, Java is difficult to operate the underlying hardware, less flexible, and needs the support of virtual machine, which occupies more resources. It is difficult for the MCU system with low configuration. Therefore, in the applications that strive to be efficient, miniaturized and perform key tasks, it is best to use assembly and C language, such as rocket control, sensor communication or reporting the orientation of spacecraft.

Although Java is a language with perfect functions, it has its own advantages and disadvantages. We should learn to choose in specific projects.