Installing Java

Oracle provides Java Platform in two types: Java Runtime Environment (JRE) and Java Development Kit (JDK). The JRE consists of the Java Virtual Machine (JVM) and other components needed to run program written using Java language. While JDK shall be composed of the JRE itself plus development tools, compilers, and also debuggers necessary for creating programs written using Java language.

The Official statement from Oracle: "The JDK is a development environment for building applications, applets, and components using the Java programming language. The JDK includes tools useful for developing and testing programs written in the Java programming language and running on the Java platform".

Because we require JDK for create Java programs, we will install the JDK, which will automatically install the JRE as well. Please download JDK below for Windows platform. There are two options, for Windows 32 bit and 64 bit version.

• Download jdk-8u71-windows-i586.exe for Windows 32 bit (181.21 MB)
• Download jdk-8u71-windows-x64.exe for Windows 64 bit (186.55 MB)

jdk-8u71 means Java Development Kit version 8 update 71. To download other JDK version or update, please visit http://www.oracle.com/technetwork/java/javase/downloads/index.html.

To check the Windows version you are using whether 32 bit or 64 bit, go to Control Panel - System and Security - System.



After downloading JDK, you can install it like other installer in Windows, just select default value and click Next. After JDK installed successfully, Java will be installed in C:\Program Files\Java\ directory by default, in this case is C:\Program Files\Java\jdk1.8.0_71.

To ensure your JDK installed successfully, open Command Prompt and type java -version and press Enter. This will show Java version you already installed.

Setting CLASSPATH

CLASSPATH is a system variable that is used to tell the program which is written in Java (including the tools included in the JDK) the location where the classes to be used. By setting the value of the CLASSPATH variable, then we can do the compilation and execution of the program that we created in any directory.

If you open Command Prompt, then type javac and press Enter, the result will look like this:



The above message appears because the CLASSPATH has not been set. But if you go to JDK bin directory then type javac and press Enter,  the result will look like this:

javac is a command to compile Java source code. javac.exe resides in JDK bin directory. This is just for sample, If CLASSPATH has not been set, you just can compile and execute Java program under JDK directory. Now we will set the CLASSPATH, so we can compile and execute Java program in any directory. The steps are as follow:

1. Go to Control Panel - System and Security - System, click Advanced system settings.
   
   
   
   
2. System Properties will appear. Click Environment Variables...
   
   


3. Environment Variables will appear. In System variables section, Scroll down and click Path in Variable column, then click Edit...
   
   
   


4. Edit System Variable will appear. Add JDK bin directory string: ";C:\Program Files\Java\jdk1.8.0_71\bin" (without quotation marks) to Variable value then click OK. Important! add Variable value, not replace.
   
   
   


5. Back to Environment Variables, then click OK.


6. Back to System Properties, then click OK.


7. Now your CLASSPATH has been set. You can compile and execute Java program in any directory. To check your CLASSPATH has been set successfully, open Command Prompt and type javac and press Enter in any directory, your console will print all parameters can be used for javac, as shown in the following image.