Java/C2/First-Java-Program/English

Title of script: Getting started with java: first program.

Author: Prathamesh Salunke

Keywords: video tutorial, Hello World, first program

Visual Cue	Narration
Slide 1 Opening slide	Welcome to the Spoken Tutorial on getting started with the First java program.
Slide 2 Learning Objectives	In this tutorial we will learn * To create a simple java program. * To compile the program. * To run the program. * About the naming conventions followed.
Slide 3 System Requirements	Here we are using Ubuntu version 11.10 and Java Development Environment jdk 1.6
Slide 4 Prerequisite	To follow this tutorial JDK 1.6 must be installed on your system. If not, for relevant tutorial please visit our website as shown.
Switch to Terminal and then to the Text Editor	Let us now write our first java program. For that you need a Terminal and a Text Editor.
Point to the gedit	I am using gedit as my Text Editor
type: class HelloWorld Highlight HelloWorld { } [ENTER]	In the text editor, we will first create the class HelloWorld. So type class HelloWorld HelloWorld is the name of the class. Open curly bracket. Press Enter and close curly bracket.
Highlight {}	The code inside this block will belong to the class HelloWorld
Click on the Save icon.	Now save the file by clicking on the Save icon. It is a good practice to save the file frequently.
Save as Dialog box	Save As Dialog box appears. Browse the location where you want to save the file.
Select Home directory Create folder Demo.	Here, in the home directory we will create a folder. Let us name it as Demo Then inside this folder we will save the file.
Type: HelloWorld.java type HelloWorld dot java	In the Name text-box, type the name of the class. In java, the name of the class and the file name should be same. Recall that the class we have created is HelloWorld. So we will save this file also as HelloWorld dot java
Highlight .java	Dot java extension is given to a java file.
Click on Save	Then click on Save button. So the file is now saved.
class HelloWorld { public static void main() { } } Highlight Main main(String arg[])	Inside the class, we write the main method. So type: public static void main within parentheses String arg Square brackets Main method marks the starting point of the program. We will describe the words public, static, void and String arg in a future tutorial. Then again, open curly bracket. Press Enter and close curly bracket.
Highlight {}	The code inside these curly brackets will belong to the main method.
Type: public static void main(String arg[]) { System.out.println(); } Highlight semicolon System.out.println(“My first java program!”);	We will now write a code to display a line on the Terminal. So type System dot out dot println parentheses semi-colon This statement is used to print a line. In Java, semi-colon is used to terminate a line. Now let us tell Java what to print. Within parentheses in double quotes type My first java program exclamation mark.
Click on Save icon	Let us Save the file by clicking on Save icon.
Switch to the Terminal	Let us go back to the Terminal.
ls cd Demo ls	Make sure that you are in the directory where your HelloWorld.java file is present. Remember that I am in my home directory. We can see that Demo is a subdirectory. So type cd Space Demo and hit Enter We see the HelloWorld.java file present in the Demo folder.
javac HelloWorld.java	Now, run the command javac Space HelloWorld dot java. This will compile the file that we have created.
ls	Alright now the file is compiled as we see no error. We can see the HelloWorld.class file created. This file can run anywhere. That is, on any Operating System. We do not need java compiler as well. Hence, java is rightly described as “write once, run anywhere.”
Switch back to the Terminal	Go back to the Terminal.
Java HelloWorld	After successful compilation, run the program using the command, java (no c) space HelloWorld (no dot java) and hit Enter.
Output	We see the output My first java program! So we have written our first java program.
Go back to text editor	Let us go back to the Text Editor.
Delete ;	Now, remove the semi-colon which is at the end of the statement.
Click on Save	Click on the Save icon.
Go to Terminal	Let us go back to the Terminal.
javac HelloWorld.java	Run the command javac Space HelloWorld dot java.
HelloWorld.java:5: ';' expected System.out.println("My first java program") ^ 1 error	The compiler gives an error. It says, a semi colon is expected on the fifth line. The up arrow points to the error statement.
Switch back to the Text Editor	Let us go back to the Text Editor. In Java, all statements are terminated with semicolons.
Type ;	So go to the fifth line. At the end of the statement add a semi-colon.
Click on Save	Click on the Save icon.
Switch back to the Terminal	Let us go back to the Terminal.
javac HelloWorld.java	Run the command javac Space HelloWorld dot java.
java HelloWorld	The file is successfully compiled as we see no errors. Now, run the program using the command java space HelloWorld and hit Enter.
Output	We see the output My first java program! This is how you can handle errors in java. As the series progresses, we will learn more about the errors.
Switch to Slides Slide 4	We now see what are the naming conventions in java. The class name should be in CamelCase. Which means each new word begins with an upper case. Example: class HelloWorld, class ChessGame. So, H of hello, W of World are in uppercase. Similarly C and G of Chess and Game respectively are in uppercase.
Slide 5	* The method name should be in mixed case. Which means that the first word should begin with a lower case. And all new words should begin with an upper case. Also the method name should be a verb.
Slide 6	* Example: showString(), main(), goToHelp().The variable name should not begin with digits. Here s of show is in lowercase and S of string is in uppercase. We cannot use keywords for our class, method or variable name. For example: We cannot use keywords like public, private, void, static and many more.
Slide 7 Summary	So in this tutorial, we have learnt to write, compile and run a simple java program. We also saw the naming conventions followed in java.
Slide 8 Assignment	For self assessment write a simple java program which prints Java file name and class name should be same. To know more about the Spoken Tutorial Project
Slide 9 About Slide	Watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it
Slide 10 About Slide	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates for those who pass an online test For more details, please write to contact@spoken-tutorial.org
Slide 11 Acknowledgment	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at http://spoken-tutorial.org/NMEICT-Intro
Slide 12 Contributor Slide	We have come to the end of this tutorial. Thanks for joining. This is Prathamesh Salunke signing off. Jai Hind.

Contributors and Content Editors

Ashwini, Chandrika, Sneha