Experience sharing-java the differences and myths in JDK and JRE!

1. Basic understanding of basic Java Concepts, JDK and JRE

1.1) Java SE (formerly J2SE)

Java Platform, Standard Edition--java platform

1.2) Java EE (formerly EE)

Java Platform, Enterprise Edition--java application Platform

1.3) Java ME (formerly J2ME)

Java Platform, Micro Edition--java System Application Platform

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Java SE (formerly J2SE)

Java SE can be divided into 4 main parts: the Java language, the JDK, the JRE, and the JVM.

1.1) Java language

--java programming language.

1.2) JDK

--java Development Kit (Java Development Kits, abbreviated JDK)

1.3) JRE

--java execution Environment (Java SE Runtime Environment, referred to as JRE)

1.4) JVM

--java virtual machines (Java virtual machine, abbreviated JVM)

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Java Key Benefits:

1.1. Object-oriented

1.2. Cross-platform

2, install the JDK (download), Install the specified directory (preferably do not keep the default path)

The concept of 7u75:

JDK Total 7th version, revised 75 times.

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Differences between JRE and standalone installed JRE in JDK:

Jre7: A separate and common JRE environment.

The tools in the JDK jre:jdk are also written in Java, and they need a set of JRE when they run.

Or the reason for this is that most of the tools in the "bin" directory are written in the Java language, and these tools run in their own JRE.

3. Environmental variables

3.1), configure the system variables, of course, user variables can be, but only for the current user, the system variables are effective.

3.2), configuration environment variable attention format, for the JDK switch convenience, and prevent misoperation.

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4, JDK directory detailed

4.1"bin" Directory

Binary shorthand, JDK tool package

4.2"db" Directory

Database shorthand, JDK7 newly added Apache derby databases, pure Java-written open source

relational database that supports the JDBC4.0 standard.

4.3"include" Directory

Some C-language header files that need to be introduced.

4.4"jre" Directory

The JRE (Java Runtime Environment) that accompanies the JDK itself.

4.5"lib" Directory

Library shorthand, some resource files and resource bundles required by the JDK.

4.6"src.zip" file

Java provides the source code compression file for the API class.

5, test A check procedure, check the configuration environment is wrong.

Class Javatest {

public static void Main (string[] args) {

System.out.println ("Java test!");

}

}

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Experience sharing-java the differences and myths in JDK and JRE!