。 javase------First Knowledge of Java

My teacher told me that fate favors a tiandaochouqin.

Sometimes in the dream of more than a dream, after all, it is only dreams,

Instead of down-to-earth steps forward to the practical.

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First knowledge of Java

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The Java------is a fully object-oriented language, independent of the platform.

------J2SE Standard Edition (Java Foundation)

Java EE Enterprise Edition (primarily for Web application development)

J2ME small version (such as apps on your phone)

------Language Features: cross-platform (principle: Different platforms have different JVMs)

-------JVM is a Java virtual machine.

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The first action you have to take to learn any language is to build the environment.

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Environment Building for Java language

------JDK (Java Development Kit)------Java Development Tools (development)

------JRE (Java Runtime) (run)------The core class libraries required by Java programs

------Java Virtual Machine (JVM)

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Note: If you are running a well-developed Java program, just install the JRE on your computer.

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In the JDK directory, the development tools are in the Bin folder.

Javac.exe Compilation Tool

Jar.exe Packaging Tools

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Configuring Environment variables

------Purpose: More convenient to use Java development tools.

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Note: Percent dynamic gets the value of an existing environment variable.

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In addition, environment variables can be temporarily configured on the DOS command line.

cd\ root directory set + environment variable name =

such as: set path = d:\haha;%path%

This method of configuring the environment variable is only valid in the current window of the DOS command line,

When you close the DOS command line and reopen the new DOS command line, it reverts to the original environment variable.

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In the DOS command line

------Javac Abc.java (javac. EXE compile source file, generate Abc.class bytecode file)

------Java ABC (Java.exe run, call JVM virtual machine)

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Written in 2014.12.13. Qingdao Chengyang. Lyq

。 javase------First Knowledge of Java