201671010144 2016-2017-2 "Java Programming"--Understanding java!

time flies really fast, not enough to enjoy a big and easy to live in the twinkling of an eye we have completed from the school to learn younger sister to seniors learn elder sister's metamorphosis. Compared to the big moment Mengmengdongdong us, the sophomore we seem to have grown a lot. The road of life is like a lot of nodes, each step is a node. For me, this semester of Java is my new node, I hope I will work harder, with almost perfect performance over this node!

first Knowledge of Java

I. Review of Java 's development history

1991 Sun 's James Gosling and others began to develop the language named Oak. Want to control the microprocessor embedded in the cable TV switch box,PDA , etc.

　　1994 renamed the Oak language to Java

　　1998 Year JDK1.2 , renamed to Java 2 Platform

version can be divided into Standard Edition J2SE, Enterprise version of Java EE, mini version J2ME

two. What is Java

Java is a computer programming language, with cross-platform, object-oriented, generic programming features, widely used in enterprise-class Web application development and mobile application development, not only absorbed the C + + The various advantages of language, but also abandoned the C + + Difficult to understand the multi-inheritance, pointers and other concepts, so the Java language has a powerful and easy to use two features. as the representative of static object-oriented programming language, the Java language implements the object-oriented theory, which allows programmers to do complex programming in an elegant way.

three. features of the Java language

1. Simple

　　Java is a relatively simple programming language. It rejects the fuzzy concepts of multi-inheritance in C + + , especially without pointers, and provides an automatic garbage collection mechanism that allows programmers to get rid of memory management headaches.

　　2. Object-oriented

　　" Object-oriented " is a major revolution in software engineering, which makes software writing more consistent with people's thinking habits, greatly improving the efficiency of programming.

Java provides classes, interfaces, inheritance, and so on. For simplicity,Java 's classes only support single inheritance, but support multiple inheritance between interfaces and support the implementation mechanism between classes and interfaces. Java fully supports dynamic binding, while C + + uses dynamic binding only for virtual functions. It can be said thatJava is a purely object-oriented programming language.

　　3. Security

because Java does not use pointers, so all accesses to memory are implemented by the object's view instance variable, so it is relatively safe.

　　4. Cross-platform

　　Java claims:Write Once,run anywhere. It all depends on the JVM. programs written in Java can be modified or not modified to run at the same time on Windows,Mac, LinUX and other systems.

　　5. Support Multithreading

multithreading can be understood as a program that has multiple tasks that can be concurrently ( also ) implementation, which can improve the execution efficiency of the program. Java is multi-threaded, and the Java language has a superior ability to handle multithreading.

6 · Dynamic Nature

　　The Java language is designed to adapt to a changing environment and it is a dynamic language. For example, classes in Java are loaded as needed, and even some are obtained over the network.

　　7. Portability

　　Java makes language declarations independent of the implementation aspect. For example,java explicitly describes the size of each base data type and its operation behavior (these data types are described by Java syntax)

　　8. High Performance　　

　　Java is a language that is compiled and interpreted first, so it is not as fast as a fully compiled language. However, in some cases performance is important, in order to support these situations, theJava designer has produced a " timely " compiler, which can be run Java bytecode translated into specific CPU(central processing Unit) of the machine code, that is, the implementation of full compilation. the Java bytecode format design takes into account the need for these " just-in- time " compilers, so the process of generating machine code is fairly straightforward, and it can produce pretty good code.

　　9. Robustness

　　Java was originally used as a language for writing consumer home electronics software, so it was designed to write highly reliable and robust software. Java eliminates some programming errors, making it fairly easy to write reliable software with it.

through a week of study, I basically mastered the Java This is a solid foundation for my next study, through the basic operations of both the command line and the integrated development environment.

201671010144 2016-2017-2 "Java Programming"--Understanding java!