Dark Horse programmer —————— Java Basics

First, software development

What is software?

Software is simply a collection of computer data and instructions, data (such as age, gender), instructions in time to tell the computer how to deal with him, computer but no one so clever ah!

Second, the graphical interface (GUI), the main feature is that simple and clear, users easy to accept, easy to get started. For command-line mode, you need a machine that requires some instructions to operate, such as a DOS system, and you need to enter some commands to complete the operation, instead of the GUI.

Third, the characteristics of the Java language: cross-platform

Can be run on different operating systems.

Principle:

Need to use the JVM (virtual machine)

PS: Different machine operating systems with different JVM

For example, Windows, Linux,mac

Iv. Introduction of development tools

Download and installation of JRE,JDK

V. Introduction of the command line

Common DOS commands

Dir lists the files and folders in the current directory:

MD: Wearing catalog

RD: Deleting a directory

CD: Enter the specified directory.

Cd.. : Returns to the top level directory

Cd\: Return to the root directory

Del: Delete the file.

Exit: Exit the System

VI. Configuring some environment variables

Java_home points to the installation path of the JDK, such as C:\jdk1.5.0_06, you should be able to find the bin, Lib and other directories under this path. It is worth mentioning that the installation path of the JDK can choose any disk directory, but it is recommended that you put a shallow directory level, if you put a deep directory.
Then, the following steps and later application you will be affected, hehe. Setup method:

      java_home=c:\jdk1.5.0_06

     path   Environment variables originally in Windows, you just need to modify it so that he points to the JDK Bin directory, so that you do not have to type a large string of paths when compiling and executing programs under the console. The Setup method is to keep the contents of the original path, and add%java_home%\bin (note, if you do not understand the DOS batch, you may not understand what is meant by the content of the percent), in fact, this is a reference to the previous set of environment variables Java_home, you write x:\ jdk_1.4.2 is also possible; you can open a console window and enter echo%java_home% to see your settings):     

path=%java_home%\bin;%path%

Again,%path% is referencing the PATH environment variable you set earlier, and you can copy the previous value.

CLASSPATH Environment variables I put in the last side, because you appear in the inexplicable strange problem 80% or more may be due to the CLASSPATH settings are not caused, so be more careful.

Seven, for the above common error message--Cannot find the file

The cause of the error

1, the file name is wrong

2. The class file is not under the current path or is not under the Classpath specified path

3. Suffix name problem

Viii. End

Hardworking people--all happy!

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Dark Horse programmer —————— Java Basics