Java Notes Collation (i), Java introduction

Version of the Java language:

J2SE (Java2 Platform standard Edition,java Platform), later renamed as: JAVA SE

Java EE (Java 2 platform,enterprise Edition,java Platform Enterprise Edition), renamed as:

J2ME (Java 2 Platform Micro Edition,java Platform mini version), renamed: Java ME

Cross-platform

"Write in one place, run Everywhere", written Java code compiled by the Java source compiler to generate bytecode files, and then by the Java Virtual machine JVM (Java computer) to the different CPUs, different operating systems, to interpret the corresponding machine code, so that Java is an object-oriented, cross-platform interpretation of language.

JRE and JDK

JRE (Java Runtime Environment) a collection of environments necessary to run Java programs, including the JVM standard implementation and the Java Core Class library. Includes two parts: Java Runtime Environment and Java plug-in. The Javaruntimeenvironment (JRE) is the Java platform on which applications can be run, tested, and transmitted. It includes the Java Virtual Machine (JVM), the Java Core Class library, and the supporting files. It does not contain development tools (JDK)-compilers, debuggers, and other tools. The JRE requires auxiliary software--java plug-in--to run applets in the browser.

The JDK (Java Development Kit) is the Java Language Software Development Kit (SDK), which is used primarily for Java applications on mobile devices and embedded devices. Java programs cannot be compiled without a JDK.

The basic components included in the JDK include:

javac– compiler, turn source program into bytecode

jar– Packaging tool to package related class files into a single file

javadoc– Document generator, extracting documents from source notes

Jdb–debugger, error-checking tool

java– running the compiled Java program (. class suffix)

Appletviewer: Applet browser, a Java browser that executes Java applets on HTML files.

Javah: Generates a C procedure that can invoke a Java procedure, or a header file that can be called by a Java program.

The Javap:java disassembler, which displays the accessible functionality and data in the compiled class file, shows the meaning of the byte code.

Jconsole:java Tools for system commissioning and monitoring

Configuration of environment variables:

See this article: http://www.cnblogs.com/xs104/p/4478096.html

Java Notes Collation (i), Java introduction