How to Install JDK 7 on Ubuntu

There are several JDK implementations available for Linux, such as Oracle JDK 7, OpenJDK, Sun JDK 6, IBM JDK and GNU Java Compiler. We shall choose the Oracle JDK 7 (Ubuntu chooses OpenJDK as its default JDK, which is not 100% compatible with Oracle JDK).

Step 1 : Check if JDK has already been Installed

 

Open a Terminal or press Ctrl + Alt + T and issue this command:

 

javac -version

 

If a JDK version number (e.g., "javac 1.7.0_{xx}") appears, JDK has already been installed. You can skip the installation and goto step 3.

 

Step 2 : Download and Install JDK

 

Goto JDK (Java SE) download site at

http://www.oracle.com/technetwork/java/javase/downloads/index.html.

Select "Java SE 7ux" ⇒ JDK ⇒ Download ⇒ "Accept Licence Agreement" ⇒ Select Linux x86 (for 32-bit system) or Linux x64 (for 64-bit system) "tar.gz" package, e.g., "jdk-7ux-linux-i586.tar.gz". The tarball will be stored in folder "~/Downloads", by default.

We shall install JDK under "/usr/lib/jvm". First, create a directory "jvm" under "/usr/lib" (with superuser authority "sudo"). Open a Terminal and issue these commands:

 

cd /usr/lib

sudo mkdir jvm

 

How to Install NetBeans on Ubuntu

To use NetBeans for Java, PHP programming, you need to first install JDK. Read "How to install JDK on Ubuntu".

Step 1 : Download netbeans

 

Download NetBeans from http://netbeans.org/downloads/. Choose platform "Linux (x86/x64)" ⇒ "Java SE". You shall receive a sh file (e.g., "netbeans-7.x-ml-javase-linux.sh") in "~/Downloads".

Set the downloaded sh file to executable and run the sh file.

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Step 2 : Install netbeans

 

Open a Terminal and type the following commands.

 

cd ~/Downloads

chmod a+x netbeans-7.x-ml-javase-linux.sh   // Set to executable for all (a+x)

./netbeans-7.x-ml-javase-linux.sh                   // Run

 

Follow the instructions to install NetBeans.

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Compile and Run a Hello-world Java Program

Step 1

 

Open "Folder" and create a new directory called "myproject" under your home directory to keep all your works.

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Step 2

 

Open "Text Editor" (gedit). Enter the following source code and save as "Hello.java" under the "~/myproject" directory created eariler.

 

    public class Hello {   // To save as "Hello.java" under "~/myproject"

       public static void main(String[] args) {

          System.out.println("Hello, world from Ubuntu!");

       }

    }

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