For the beginner one of the difficult and confusing task
is to set path and classpath environment variables.
Path
is nothing but setting up an environment for operating system. Path is a system
variable used to tell to Operating System all locations of executable files. Operating
System will look in this path variable for executable files.
Classpath
is nothing but setting up an environment for java. Classpath is pure java
variable, which is used to tell the Java Virtual Machine or the Java compiler
where to look for user-defined classes and packages.
For example,assume that Java
is installed in C:\Program Files\Java\jdk1.7.0_25\ and your code is in C:\Sample\example.java,
then path and classpath should be set to like this:
classpath=C:\Sample
path= C:\Program
Files\Java\jdk1.7.0_25\bin;
Or
path=%JAVA_HOME%\bin;
where JAVA_HOME is pointing to Home directory “C:\Program
Files\Java\jdk1.7.0_25”, where jdk is installed
Whenever you try to compile
a program using javac, JVM will search for javac in current directory where
your program is residing, If it does not find javac and other executables in
current directory then it will search in the directories where the path
variable is set to. So setting path variable allows you to
execute your program from any directory as location of executables java and
javac is retrieved through path variable.
If you have not set path
variable then it will show error like “javac is not a recognized command” .
hence to remove this error set path environment variable as follows:
- Command to set path variable from command prompt
·
Set
path=”C:\Program Files\Java\jdk1.7.0_25\bin”
·
Set
path=%path%;”C:\Program Files\Java\jdk1.7.0_25\bin”
Here in second command we
are just adding our path value to existing value of path variable.
- Command to remove value from path variable
·
Set path=
This will remove directory
path from environment variable.
- Check whether environment variables are set correctly or not
·
If your
environment variables are set correctly, then windows should recognize these
commands.
C:\>
java OR
C:\>
javac
·
you can see
current value of path variable by following command
C:\>
echo %path%
