In sun's 1991
R&d needs: memory small different CPU
In the * * James Gosling * * (James? Gosling) led in 1995 formally established.
2004 1.5 release (important grammar upgrade changes)
Now bought by oracle company named java52009 sun Java version update once every six months
The characteristics of the Java language
Ensure
Ava source code only need to write a
Compiled to bytecode translation class loading (Java virtual machine runtime data storage execution engine)
The JVM to run on a different platform (operating system) Java language and platform independent
* * open source JVM platform-specific (open source, free)
Object-oriented
Interactive feature
Multithreading mechanisms
Dynamic memory management mechanism
Security
3. Java language architecture
JavaSE: Java Standard Edition (Java Standard Edition) contains Java based core classes: string, date, collection, unusual, IO, threads, GUI, network programming
JavaEE: Java Enterprise Edition (Java Enterprise Edition) contained in the JavaEE JavaSE, servlet (applet) server, JSP
JavaME: Java Micro Edition (Java Micro Edition) JavaME has been replaced by the android development # 4. The operating mechanism of the Java language to create. Java file (source code) -- -- -- -- -- & gt; The compiler -- -- -- -- -- & gt; .class files (bytecode) -- -- -- -- -- - & gt; Different platforms of the JVM -- -- -- -- -- - & gt; Translation -- -- -- -- -- - & gt; Instructions -- -- -- -- -- & gt; Platform running Java # 5 * * * * run the installation and configuration download https://www.oracle.com/java/technologies/javase-downloads.html Environment jdkJDK (Java Development Kit Java Development Kit) JDK on the developer's Kit contains some tools (compiler, packaging, testing tools), JRE (Java Runtime Environment for Java Runtime Environment), the JVM is responsible for executing the class file # 6. To develop the first Java program ` ` ` javapublic class Hello {public static void main (String [] args) {System. Out. Print (" Hello world "); }} ` ` ` by javac command will. Compiled into a Java file. The class file and then run through the Java command classes due to the use of these commands, need to the bin directory to. Very inconvenient solution: in the heart of the system environment variable Path D: \ ProgramFiles \ Java \ jdk1.8.0 _261 configuration \ bin to the Path of the Java command can be used in any directory