[java] Environment variables for java installation

How to set the environment variables for Java in Windows (the classpath)?

The JDK installation instructions explain exactly how to set the PATH, for different versions of Windows.

Normally you should not set the CLASSPATH environment variable. If you leave it unset, Java will look in the current directory to find classes. You can use the -cp or -classpath command line switch with java or javac.

In Windows inorder to set

Step 1 : Right Click on MyComputer and click on properties .

Step 2 : Click on Advanced tab

Step 3: Click on Environment Variables

Step 4: Create a new class path for JAVA_HOME

Step 5: Enter the Variable name as JAVA_HOME and the value to your jdk bin path ie c:\Programfiles\Java\jdk-1.6\bin and

NOTE Make sure u start with .; in the Value so that it doesn't corrupt the other environment variables which is already set.

Step 6 : Follow the Above step and edit the Path in System Variables add the following ;c:\Programfiles\Java\jdk-1.6\bin in the value column.

Step 7 :Your are done setting up your environment variables for your Java , In order to test it go to command prompt and type

 java   

who will get a list of help doc

In order make sure whether compiler is setup Type in cmd

  javac

who will get a list related to javac

Hope this Helps !

Set java Environment variable in Centos / Linux

/home/ vi .bashrc

export JAVA_HOME=/opt/oracle/product/java/jdk1.8.0_45

export PATH=$JAVA_HOME/bin:$PATH

java -version

For deployment better to set up classpath exactly and keep environment clear. Or at *.bat (the same for linux, but with correct variables symbols):

CLASSPATH="c:\lib;d:\temp\test.jar;<long classpath>"
CLASSPATH=%CLASSPATH%;"<another_logical_droup_of_classpath" 
java -cp %CLASSPATH% com.test.MainCLass

Or at command line or *.bat (for *.sh too) if classpath id not very long:

java -cp "c:\lib;d:\temp\test.jar;<short classpath>"

--- To set java path ---

There are two ways to set java path

A. Temporary

1. Open cmd
2. Write in cmd : javac

If java is not installed, then you will see message:

javac is not recognized as internal or external command, operable program or batch file.

3. Write in cmd : set path=C:\Program Files\Java\jdk1.8.0_121\bin
4. Write in cmd : javac

You can check that path is set if not error has been raised.

It is important to note that these changes are only temporary from programs launched from this cmd.

NOTE: You might have to run the command line as admin

B. Permanent

1. Righ-click on "My computer" and click on properties
2. Click on "Advanced system settings"
3. Click on "Environment variables"
4. Click on new tab of user variable
5. Write path in variable name
6. Copy the path of bin folder
7. Paste the path of the bin folder in the variable value
8. Click OK

The path is now set permanently.

TIP: The tool "Rapid Environment Editor" (freeware) is great for modifying the environment variables and useful in that case

TIP2: There is also a faster way to access the Environment Variables: press Win+R keys, paste the following %windir%\System32\rundll32.exe sysdm.cpl,EditEnvironmentVariables and press ENTER

Keep in mind that the %CLASSPATH% environment variable is ignored when you use java/javac in combination with one of the -cp, -classpath or -jar arguments. It is also ignored in an IDE like Netbeans/Eclipse/IntelliJ/etc. It is only been used when you use java/javac without any of the above mentioned arguments.

In case of JAR files, the classpath is to be defined as class-path entry in the manifest.mf file. It can be defined semicolon separated and relative to the JAR file's root.

In case of an IDE, you have the so-called 'build path' which is basically the classpath which is used at both compiletime and runtime. To add external libraries you usually drop the JAR file in a (either precreated by IDE or custom created) lib folder of the project which is added to the project's build path.

In Windows 7, right-click on Computer -> Properties -> Advanced system settings; then in the Advanced tab, click Environment Variables... -> System variables -> New....

Give the new system variable the name JAVA_HOME and the value C:\Program Files\Java\jdk1.7.0_79 (depending on your JDK installation path it varies).

Then select the Path system variable and click Edit.... Keep the variable name as Path, and append C:\Program Files\Java\jdk1.7.0_79\bin; or %JAVA_HOME%\bin; (both mean the same) to the variable value.

Once you are done with above changes, try below steps. If you don't see similar results, restart the computer and try again. If it still doesn't work you may need to reinstall JDK.

Open a Windows command prompt (Windows key + R -> enter cmd -> OK), and check the following:

java -version

You will see something like this:

java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

Then check the following:

javac -version

You will see something like this:

javac 1.7.0_79

For Windows:

• Right click on 'My Computers' and open 'Properties'.
• In Windows Vista or Windows 7, go to "Advanced System Settings". Else go to next step.
• Go to 'Advanced Tab' and click on Environment Variables button.
• Select 'Path' under the list of 'System Variables', and press Edit and add C:\Program Files\java\jdk\bin after a semicolon.
• Now click on 'new' button under system variables and enter 'JAVA_HOME' as variable name and path to jdk home directory (ex. 'C:\Program Files\Java\jdk1.6.0_24' if you are installing java version 6. Directory name may change with diff. java versions) as variable_value.

I am going to explain here by pictures for Windows 7.

Please follow the following steps:

Step 1: Go to "Start" and get into the "My Computer" properties

Step 2: Go to "Advance System Setting" and click on it.

Step 3: Go to "Start" and get into the "My Computer" properties

Step 4: The dialog for Environment variable will open like this:

Step 5: Go to path and click on edit.

Step 6: Put the path of your JDK wherever it resides up to bin like you can see in the picture. Also add path from your sdk of Android up to the Platform Tools:

Java SE Development Kit 8u112 on a 64-bit Windows 7 or Windows 8

Set the following user environment variables (== environment variables of type user variables)

• JAVA_HOME : C:\Program Files\Java\jdk1.8.0_112
• JDK_HOME : %JAVA_HOME%
• JRE_HOME : %JAVA_HOME%\jre
• CLASSPATH : .;%JAVA_HOME%\lib;%JAVA_HOME%\jre\lib
• PATH : your-unique-entries;%JAVA_HOME%\bin (make sure that the longish your-unique-entries does not contain any other references to another Java installation folder.

Note for Windows users on 64-bit systems:

Progra~1 = 'Program Files'
Progra~2 = 'Program Files(x86)'

Notice that these environment variables are derived from the "root" environment variable JAVA_HOME. This makes it easy to update your environment variables when updating the JDK. Just point JAVA_HOME to the fresh installation.

There is a blogpost explaining the rationale behind all these environment variables.

Optional recommendations

• Add an user environment variable JAVA_TOOL_OPTIONS with value -Dfile.encoding="UTF-8". This ensures that Java (and tools such as Maven) will run with a Charset.defaultCharset() of UTF-8 (instead of the default Windows-1252). This has saved a lot of headaches when wirking with my own code and that of others, which unfortunately often assume the (sane) default encoding UTF-8.
• When JDK is installed, it adds to the system environment variable Path an entry C:\ProgramData\Oracle\Java\javapath;. I anecdotally noticed that the links in that directory didn't get updated during an JDK installation update. So it's best to remove C:\ProgramData\Oracle\Java\javapath; from the Path system environment variable in order to have a consistent environment.

Under Linux: http://lowfatlinux.com/linux-environment-variables.html

And of course, you can retrieve them from Java using:

String variable = System.getProperty("mykey");

For Windows 7 users:

Right-click on My Computer, select Properties; Advanced; System Settings; Advanced; Environment Variables. Then find PATH in the second box and set the variable like in the picture below.

In programming context you can execute SET command (SET classpath=c:\java) or Right click on your computer > properties > advanced > environment variables.

In a batch file you can use

SET classpath=c:\java
java c:\myapplication.class

1. Download the JDK
2. Install it
3. Then Setup environment variables like this :
4. Click on EDIT

5. Then click PATH, Click Add , Then Add it like this: