Difference between revisions of "Java/C2/First-Java-Program/English"

Opening slide

Learning Objectives

* To create a simple java program.

* To compile the program.

* To run the program and

* About the naming conventions followed.

System Requirements

• Ubuntu version 11.10 and
• Java Development Environment jdk 1.6

Prerequisite

If not, for relevant tutorial please visit our website which is as shown.

For that you need a Terminal and you need a Text Editor.

class HelloWorld

Highlight HelloWorld

{

}

[ENTER]

So type class HelloWorld

HelloWorld is the name of the class.

then Open curly bracket.

 Enter and close curly bracket.

It is a good practice to save the file frequently.

Browse the location where you want to save your file.

Create folder Demo.

Let us name it Demo and press enter

Then inside this folder we will save the file.

HelloWorld.java

type HelloWorld dot java

In java, the name of the class and the file name should be same.

Recall that we created class HelloWorld.

So we will save the file as HelloWorld dot java

So the file is now saved.

{

public static void main()

{

}

}

Highlight Main

main(String arg[])

So type:

public static void main parentheses inside parentheses String arg Square brackets

Main functions marks the starting point of the program.

We will describe public, static, void and String arg in a future tutorial.

Then once again, open curly bracket.

Press Enter and close curly bracket.

public static void main(String arg[])

{

System.out.println();

}

Highlight semicolon

System.out.println(“My first java program!”);

So inside main method typeSystem dot out dot println parentheses semi-colon

This is the statement used to print a line.

 semi-colon is used to terminate a line.

Now let us tell Java what to print.

So Within parentheses in double quotes type My first java program exclamation mark.

cd Demo

ls

Remember that I am in my home directory.

So type cd Space Demo and hit Enter

We see HelloWorld.java file present in the Demo folder.

This compile the file that we have created.

We can see that 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.”

java (no c) space HelloWorld (no dot java extension) and hit Enter.

So we have written our first java program.

System.out.println("My first java program")

^ 

1 error

It says, a semi colon is expected on the fifth line.

The up arrow points to the error statement.

In Java, all statements are terminated with semicolons.

Now, run the program using the command

java HelloWorld and .

This is how you can handle errors in java.

As the series progresses, we will learn more about the errors.

Slide 4

• 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 and W of World are in uppercase.

Similarly C and G of Chess and Game respectively are in uppercase.

• Which means that the first word should begin with a lower case.
• And all new words followed should begin with an upper case.
• Also the method name should be a verb.

• We cannot use keywords for our class, method or variable name.
• For example: cannot use keywords like public, private, void, static and many more.

Summary

We also saw the naming conventions followed in java.

Assignment

To know more about the Spoken Tutorial Project

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

About Slide

• Conducts workshops using spoken tutorials

• Gives certificates for those who pass an online test

• For more details, please write to contact@spoken-tutorial.org

Acknowledgment

• 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

Contributor Slide

Thanks for joining.

This is Prathamesh Salunke signing off.

Jai Hind.