Difference between revisions of "Java/C2/Errors-and-Debugging-in-Eclipse/English"

Welcome

Learning Objectives

what are the possible error while writing a simple Java Program,

how to identify those errors and rectify them using eclipse.

Software Versions

Ubuntu 11.10,

Eclipse 3.7

Prerequisites

how to create and run a Java Program in Eclipse.

If not, for relevant tutorial please visit our website as shown [1]http://spoken-tuitorial.org

Possible Errors

• Missing semicolon(;)
• Missing double quotes(" ") Mis-match of filename and classname
• Typing the print statement in lower-case

{Pause for a few seconds}

• Missing semicolon(;)
• Missing double quotes(" ") around the message
• Mis-match of filename and classname and
• Typing the print statement in lower-case

We shall write a program and then make each of these errors and see what happens in Eclipse

{Eclipse should contain the project DemoProject used in previous tutorial}

And the file ErrorFree.java with these lines of code.

public class ErrorFree

{

public static void main(String args[])

{

System.out.println(Hello World)

}

}

We shall create a new class in the project and use it New Class. Let us name the class Error Free and select methods stubs public static Void main

Let us minimise the package explorer. Remove the comments and add the print statement to the few errors 

In this case, the System.out.println line has an errors and hence their is the red cross mark on the left.

This is because we have to end every statement of a Java program with a semicolon.

Save the file with Ctrl s.

.

Without the quotes, Java thinks that HelloWorld is the name of a variable.

Ctrl s to Save. We see that the red cross mark have gone and the program is error free. So let us run the program and see what happens.

HelloWorld

Type the class name and Finish

Point to the created file name and class name.

It happens due to a mismatch of file name and class name.

It does not happens usually on Eclipse.

This is because we use the New Class wizard to create a file and eclipse

creates a file automatically

So let us stimulate the error , by changing the class name.

I

Change errorfree to ErrorFree

Let us replace the capital S with a small s.

And error message reads  system cannot be resolved.

This means Java is expecting a class or object or a variable by the name system.

But there is nothing like system object in the code.

Change s to S

 Change to 'System' (java.lang)

You can see that once we change it to capital S the error is missing.

Slide 6

Summary

In this tutorial we have seen what are the typical errors while writing a Java program and

how to identify and rectify them using Eclipse.

Assignment

• Watch the video available at[2]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

Watch the video available at the following link, that summarises the project.Alternatively, you can download and watch it.

• Conducts workshops using spoken tutorials

• Gives certificates for those who pass an online test

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

Gives certificates for those who pass an online test. For more details, please write to contact AT spoken HYPHEN tutorial DOT org.

• 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

Itis supported by the National Mission on Education through ICT, MHRD, Government of India.

More information on this Mission is available at spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro

• This tutorial has been contributed by TalentSprint
• www.talentsprint.com

• Thanks for joining

Thanks for joining.