Java direction of back-end development engineer

Back-end development engineer java? Employment direction: the construction and maintenance of Renren, Qunar and Meituan.

Java is an object-oriented programming language, which not only absorbs the advantages of C++ language, but also abandons the concepts of multiple inheritance and pointers that are difficult to understand in C++, so Java language has two characteristics: powerful function and simple use. As the representative of static object-oriented programming language, Java language perfectly realizes the object-oriented theory and allows programmers to carry out complex programming in an elegant way of thinking.

JDK(Java Development Kit), also known as Java development kit or Java development tool, is a program development environment for writing Java Applet and applications. JDK is the core of Java, including Java runtime environment, some Java tools and Java API.

Whatever the Java application server is, it has a built-in JDK version. The mainstream JDK is released by Sun Company. Besides Sun, many companies and organizations have developed their own JDK, such as Jrocket developed by IBM, J Rocket developed by BEA and J Rocket developed by GNU.

Working principle:

Java programming language, Java class file format, Java virtual machine and Java application program interface need to be involved simultaneously when editing and running a Java program. Use word editing software (such as Notepad, WordPad, UltraEdit, etc.). ) or integrated development environment (Eclipse, MyEclipse, etc. Define different classes in Java source files, and access the resource system by calling methods in the classes (implementing Java API).

Compile the source file into binary intermediate code, store it in the class file, then run the class file by running the Java virtual machine corresponding to the operating system platform environment, execute the bytecode generated by compilation, and call the methods implemented in the class file to meet the Java API call of the program.