Day1 - Java learning Java language is introduced and the environment-CodePudding

After graduation for software implementation, itself a bit Java based, now want to study Java outside working hours, every day to do some notes, motivate yourself every day, hope to have some help to turn to implement development friends, software deployment project implementation does not go to the scene to customers, and training, usually more than small companies will require only the SQL table LianZha and good communication skills, but the implementation of the early stage of the general the wages were low, but the work is relatively easy, now from Java to start reviewing the beginning and the basis of
1. Java language description
Java by Sun Microsystems company launched Java object-oriented programming language (hereinafter referred to as the Java language) and the floorboard of the Java platform, Java is the father of James Gosling and officially launched in 1995, Java was originally called Oak, in 1991 is designed for consumer electronics embedded chip, in 1995 changed its name to Java, and redesigned for developing Internet applications, the charm of Java: cross-platform, dynamic Web, Internet computing, from then on, Java is widely accepted and promoted the rapid development of the Web, commonly used browsers have support for Javaapplet, on the other hand, Java technology is also constantly updated, Java since its very popular, is developing rapidly, to form a strong shock, c + + language in the global cloud computing and mobile Internet industry environment, Java is more has the significant advantages and broad prospects,
2. Java language features
(1) the cross-platform: cross-platform sex refers to the software can not bound by computer hardware and operating system in normal operation of any computer environment, Java's built-in virtual machine well realize the cross-platform, after compiling Java source code to generate a binary bytecodes is has nothing to do with the platform, but can be identified by the Java virtual machine a machine code instruction, the Java virtual machine provides a byte code to the underlying hardware platform and operating system barrier, making the Java language elements are cross-platform,

(2) simple: the Java language is a fairly simple "object-oriented programming language, Java language all difficult to understand in the c + + language is omitted, the easily confused features of header files, for example, pointer, structure, unit, operator overloading, virtual base classes, etc., it is more rigorous, concise,

(3) : object-oriented technology makes object-oriented application development become simple and easy to use, save code, Java is an object-oriented language, also inherited the object-oriented many benefits, such as code extension, code reuse, etc.,

(4) security: Java compilation for the Java language and semantic checks, to make sure every variables corresponding to a corresponding values compiled to generate Java classes, runtime Java classes need class loader loaded, and through the bytecode verifier is check before they can run, Java classes used in the network, to set its permissions, is guarantees the access to the user's security,

Multithreading: (5) is a lightweight process, a feature is indispensable in modern programming, multi-threaded processing capacity enables the program to have better interactivity, real-time,
3. Java environment build
Learn before Java first have to choose the right tools and basic environment is, first of all, computers have to install the JDK, as to download and install the tutorial to baidu, baidu is the best teacher, and then to configure Java environment variable (JAVA_HOME, CLASSPATH, Path)
1, the environment variable configuration
* "my computer" - right - "properties" - (left) advanced system Settings - (popup window at the bottom right corner) environment variable configuration;
* create JAVA_HOME, values are just the JDK installation directory, you than C: \ Program Files \ Java \ jdk1.8.0 (x86) _144;
* create a CLASSPATH, value is; % JAVA_HOME % \ lib. % JAVA_HOME % \ lib \ tools. The jar (note that the front a little;
* edit Path, put the value in the % JAVA_HOME % \ bin in front; % JAVA_HOME % \ jre \ bin.
* variable to add process after all remember, every time add something behind should have a semicolon ";" , pay attention to check whether letters and semicolons add right,
2, check the installation and configuration of
* run the CMD (Windows + R or click on the start menu at the bottom right of the input point), in the command line window of an input Java version and javac version two command check,
Now, choose the second development tools eclipse or idea enterprise with nothing more than the two,

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