Java Records-Basic JDK

1. Java is divided into three systems:
Java SE (j2se,java2 Platform Standards Edition, Standard Edition)
Java EE (J2ee,java 2 Platform Enterprise Edition, Corporate Edition)
Java ME (J2me,java 2 Platform Micro Edition, miniature version)
2, Java was launched by Sun (2009 by Oracle company to buy $74)
3. JDK and JRE:
Jdk:java Development Kit (Java Development Essentials)
Jre:java Runtime Environment (Java execution Environment)
The JDK contains the JRE
JDK version: jdk1.4,jdk1.5 (5.0), JDK1.6 (6.0), JDK1.7 (7.0), JDK1.8 (8.0)
4. Java use:
Download JDK;
Install JDK;
Setting environment variables (user variables or system variables, pointing to the bin directory in the JDK installation directory for easy command-line execution of Java);
Compile run (compile: Javac Test.java, run: Java test);
5, the class file is a bytecode file, the program finally executes the bytecode (bytecode) file.
6. You can use Windows Notepad to write Java programs directly, or you can use advanced text editing tools such as Editplus,ultraedit to write Java programs. You can also write using the Professional IDE (Integrated development environment).
7. JVM (Java virtual Machine,java vm)
Java is a cross-platform language that really executes not binary code, but byte code.
Java is cross-platform, and the JVM is not cross-platform (JVM is written in C language)
The reason why Java can be cross-platform is essentially that the JVM is not cross-platform.

Java Records-Basic JDK