JAVA PATH and CLASSPATH Settings

PATH and CLASSPATH for JAVA

This section explains how to use the PATH and CLASSPATH environment variables on Microsoft Windows, Solaris, and Linux. Consult the installation instructions included with your installation of the Java Development Kit (JDK) software bundle for current information.

After installing the software, the JDK directory will have the structure shown below.

The bin directory contains both the compiler and the launcher.

Update the PATH Environment Variable

You can run Java applications just fine without setting the PATH environment variable. Or, you can optionally set it as a convenience.

Set the PATH environment variable if you want to be able to conveniently run the executables javac.exe, java.exe, javadoc.exe, and so on) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable every time you run it, such as:

C:\Java\jdk1.7.0\bin\javac MyClass.java

The PATH environment variable is a series of directories separated by semicolons (;). Microsoft Windows looks for programs in the PATH directories in order, from left to right. You should have only one bin directory for the JDK in the path at a time (those following the first are ignored), so if one is already present, you can update that particular entry.

The following is an example of a PATH environment variable:

C:\Java\jdk1.7.0\bin;C:\Windows\System32\;C:\Windows\;C:\Windows\System32\Wbem

It is useful to set the PATH environment variable permanently so it will persist after rebooting. To make a permanent change to the PATH variable, use the System icon in the Control Panel. The precise procedure varies depending on the version of Windows:

Windows XP

1. Select Start, select Control Panel. double click System, and select the Advanced tab.
2. Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New.
3. In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

Windows Vista:

1. From the desktop, right click the My Computer icon.
2. Choose Properties from the context menu.
3. Click the Advanced tab (Advanced system settings link in Vista).
4. Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New.
5. In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

Windows 7:

1. From the desktop, right click the Computer icon.
2. Choose Properties from the context menu.
3. Click the Advanced system settings link.
4. Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New.
5. In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

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Note: You may see a PATH environment variable similar to the following when editing it from the Control Panel:

%JAVA_HOME%\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem

Variables enclosed in percentage signs (%) are existing environment variables. If one of these variables is listed in the Environment Variables window from the Control Panel (such as JAVA_HOME), then you can edit its value. If it does not appear, then it is a special environment variable that the operating system has defined. For example, SystemRoot is the location of the Microsoft Windows system folder. To obtain the value of a environment variable, enter the following at a command prompt. (This example obtains the value of the SystemRoot environment variable):

echo %SystemRoot%

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Update the PATH Variable (Solaris and Linux)

You can run the JDK just fine without setting the PATH variable, or you can optionally set it as a convenience. However, you should set the path variable if you want to be able to run the executables (javac, java, javadoc, and so on) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable every time you run it, such as:

% /usr/local/jdk1.7.0/bin/javac MyClass.java

To find out if the path is properly set, execute:

% java -version

This will print the version of the java tool, if it can find it. If the version is old or you get the error java: Command not found, then the path is not properly set.

To set the path permanently, set the path in your startup file.

For C shell (csh), edit the startup file (~/.cshrc):

set path=(/usr/local/jdk1.7.0/bin )

For bash, edit the startup file (~/.bashrc):

PATH=/usr/local/jdk1.7.0/bin:
export PATH

For ksh, the startup file is named by the environment variable, ENV. To set the path:

PATH=/usr/local/jdk1.7.0/bin:
export PATH

For sh, edit the profile file (~/.profile):

PATH=/usr/local/jdk1.7.0/bin:
export PATH

Then load the startup file and verify that the path is set by repeating the java command:

For C shell (csh):

% source ~/.cshrc
% java -version

For ksh, bash, or sh:

% . /.profile
% java -version

Checking the CLASSPATH variable (All platforms)

The CLASSPATH variable is one way to tell applications, including the JDK tools, where to look for user classes. (Classes that are part of the JRE, JDK platform, and extensions should be defined through other means, such as the bootstrap class path or the extensions directory.)

The preferred way to specify the class path is by using the -cp command line switch. This allows the CLASSPATH to be set individually for each application without affecting other applications. Setting the CLASSPATH can be tricky and should be performed with care.

The default value of the class path is ".", meaning that only the current directory is searched. Specifying either the CLASSPATH variable or the -cp command line switch overrides this value.

To check whether CLASSPATH is set on Microsoft Windows NT/2000/XP, execute the following:

C:> echo %CLASSPATH%

On Solaris or Linux, execute the following:

% echo $CLASSPATH

If CLASSPATH is not set you will get a CLASSPATH: Undefined variable error (Solaris or Linux) or simply %CLASSPATH% (Microsoft Windows NT/2000/XP).

To modify the CLASSPATH, use the same procedure you used for the PATH variable.

Mobile balance transfer

Mobile balance transfer trick for airtel, aircel, vodafone, tata docomo, bsnland idea

Here is how to do a balance talktime transfer from a prepaid mobile number to any number within the same provider. The balance transfer service is supported by airtel, aircel, vodafone, bsnl and idea. The process is very simple and easy to follow.

Airtel

Dial *141# and follow the on screen instructions.

select "share talktime option".

The *141# menu of airtel is filled with many useful option such as call me back sms on low balance etc. you can read more on call me back sms here.

Both airtel prepaid and postpaid users can transfer balance to any airtel prepaid user.

Transfer amount is to be between rs 5 and rs 50. you can also transfer rs 51 and rs 101 asgift. You must have minimum balance of rs 20 to share your balance.

Aircel

Dial *122*666# and follow the instruction.

Minimum transfer amount is rs 5 and maximum transfer amount is rs 100.

Processing fee is rs 1 per transaction and you can do only one transaction per day.

Balance transfer is possible between two prepaid numbers only.

BSNL

Type in message in the following format.

GIFT<space><mobile number><space><amount>

and send it to 53733.

There are space between gift mobile number and amount.

Supports transfers from rs 5 to rs 50.

Vodafone

To do gift recharge on vodafone just dial in the following format.

*131*<mrp>*<receiver number>#

You can transfer min rs 5 and maximum rs 30.

The processing fee is rs 1 for transfer in the range of 5 rs to 9rs, rs 2 for transfer in range ofrs 10 to rs 24, rs 3 for transfer in range of rs 25 to rs 30.

One can donate balance only once in a day and a receiver can receive balance upto 3 times a day.

Tata Docomo

Only buddy net users in tata docomo can transfer balance. If you are a buddy net user then you can transfer your balance to any prepaid docomo number. Docomo users can even do a reverse transfer. Reverse transfer means you can take back the amount you gifted to your friend.

to transfer balance on docomo compose message as shown.

"BT<space>Target Mobile Number<space>Amount"

And send to 54321.

The transfer will be charged at rs1 per transaction.

For doing the reverse transfer on tata docomo compose message as shown.

"RBT<space>Transaction ID" and send it to 54321.

And send it to 54321. reversal of the gifted amount is subject to the balance availability of the your friend and reverse transferis free of any transaction charge.

Idea

To do balance transfer from idea type message as shown.

"GIVE<space>mobile number<space>amount"

And send it to 55567.

Idea users can also transfer by sending ussd code in the following format ­.

*567*mobile number*amount#

idea charge rs 2 for each transaction as processing fee.

So that was all about the balancetransferring tricks on various service providers. The balance transferring method of airtel, aircel, vodafone, tata docomo, bsnl and idea may change from time to time, so please try to stay updated with the latest format for the transfer as this is a emergency service in most cases.

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