How to set up java

How to set up java?

After the installation is completed according to the system classification of 32-bit or 64-bit,

You need to set the environment variables. Specifically, right-click "My Computer (Computer)"-"Properties"- - "Advanced System Settings" - "Advanced" - "Environment Variables"

Set the three system variables JAVA_HOME PATH CLASSPATH. If not, just add them.

JAVA_HOME points to the JDK Installation path, such as C:\jdk1.5.0_06, you should be able to find bin, lib and other directories in this path.

( I am using the new system configuration tonight. I don’t know why I need to add bin to run it in CMD. JAVA_HOME=C:\jdk1.5.0_06\bin; The following is the online practice that can be used and posted. Note that JDK and Eclipse must have the same bit number before they can be used. They cannot be programs with different bit numbers. This has been practiced, otherwise an error will be reported and cannot be used. If you need to uninstall the JDK, the JDK cannot directly delete the folder. You must use the uninstall method, otherwise it cannot be used anymore. The JDK may not be uninstallable. You can only use it by reinstalling the OS. I have encountered it before)

JAVA_HOME=C:\jdk1.5.0_06

PATH environment variable originally exists in Windows. You only need to modify it so that it points to the bin directory of the JDK, so that you can There is no need to type in a long list of paths when compiling and executing the program under the console. The setting method is to retain the original PATH content and add %JAVA_HOME%\bin

(Note, if you don’t understand DOS batch processing, you may not understand what the content caused by %% is. Meaning; in fact, here is a reference to the environment variable JAVA_HOME set in the previous step. You can also write it as x:\JDK_1.4.2; you can open a console window and enter echo %JAVA_HOME% to see your setting results)

PATH=%JAVA_HOME%\bin;%PATH%

Similarly, %PATH% refers to the PATH environment variable you set before. You can just copy the previous value.

I put the CLASSPATH environment variable at the end because more than 80% of the inexplicable strange problems you have in the future may be caused by incorrect CLASSPATH settings, so be extra careful.

CLASSPATH=.;%JAVA_HOME%\lib;%JAVA_HOME%\lib\tools.jar

The first thing to pay attention to is the ".;" at the front. If you can't see clearly, I'll read it to you - period semicolon. This tells the JDK to first search for the CLASS file in the current directory when searching for CLASS - why this is done? This is due to the security mechanism of LINUX. LINUX users understand it very well, but WINDOWS users have a hard time understanding it (because the default search order of WINDOWS is Search the current directory first, then search the system directory, and then search the PATH environment variable setting).

Why is the specific file tools.jar specified after CLASSPATH? Is it okay not to specify? Obviously not, if it works I can still be so rosy! :) This is determined by the import mechanism and jar mechanism of the Java language. You can check the information to solve it.

Recommended tutorial: "java learning"

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