Java Basic Learning Notes--1

1. JDK, JRE, JVM relationships

Jdk:java Development Kit, Java Development Kit

Jre:java runtime Environment, Java Runtime Environment

Jvm:java virtual machines, Java VM

2 . java Program compilation Run process

The Java source file is first compiled into a. Class bytecode file, and then the. class file can be executed by the JVM.

The JVM is a software, Java Virtual machine that is installed inside the operating system and provides a running environment for. Class bytecode.

The principle of one-time compilation and multiple runs:

Java officially provides a different platform for the JVM software, these JVMs follow the same standard, as long as the standard. class file, you can run on different platforms of the JVM, and achieve the same effect.

3. Installation of the JDK under Windows and configuration of environment variables
1) Download and install the JDK
2) Configuring the Computer environment variables
Java_home:

is the folder path where the JDK is installed, such as C:\Program files\java\jdk1.6.0_10;
Path:

The bin directory under the JDK installed,%java_home%\bin;
ClassPath:
.; %java_home%\lib;%java_home%\lib\dt.jar;
%java_home%\lib\tools.jar;

Java Basic Learning Notes--1