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How to use the Eclipse Debugger? [message #1768608]

Thu, 20 July 2017 14:13

RajibKumar Bandopadhyay

Messages: 58
Registered: July 2014

Member

Hi!
Are there any help file available on the usage of the Eclipse Debugger?

Suppose I have the following console output. What does it say about the problem? The codes are posted hereunder:

Enter Length : 1.5
Exception in thread "main" java.util.InputMismatchException
	at java.util.Scanner.throwFor(Scanner.java:857)
	at java.util.Scanner.next(Scanner.java:1478)
	at java.util.Scanner.nextInt(Scanner.java:2108)
	at java.util.Scanner.nextInt(Scanner.java:2067)
	at areaandperimeterofarectangle.AreaAndPerimeterOfARectangle.main(AreaAndPerimeterOfARectangle.java:30)

Will it be possible to understand why the error happened, without looking at the .java code?
What does each line on the above console outputs signify?

[Updated on: Thu, 12 October 2017 15:47] by Moderator

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Re: How to use the Eclipse Debugger? [message #1768614 is a reply to message #1768608]

Thu, 20 July 2017 15:09

Ed Merks

Messages: 30903
Registered: July 2009

Senior Member

Google "how to use eclipse debugger" and you'll find all kinds of matches, including this one: http://www.vogella.com/tutorials/EclipseDebugging/article.html

In Eclipse's Console view the stack trace will act as a hyper link to navigate to the source. Likely you need to look at source code and understand it to see what's going wrong. Of course the method you call has javadoc and you can read that too.

You can Google "java stack trace" to find things like this: https://stackoverflow.com/questions/3988788/what-is-a-stack-trace-and-how-can-i-use-it-to-debug-my-application-errors

Google is your friend. Enter the question and you will find answers that already exist.

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Re: How to use the Eclipse Debugger? [message #1768627 is a reply to message #1768614]

Thu, 20 July 2017 17:38

RajibKumar Bandopadhyay

Messages: 58
Registered: July 2014

Member

I know where the code went wrong and how it went wrong! I was wondering whether it was possible to look at the terminated output of the console and say what went wrong! Wondering whether the console output was legible and the error was traceable from the console output!
I am attaching the debugging outputs here. The Variables- and the Breakpoints- windows are both blank.
index.php/fa/30056/0/

Google can wait till I find out whether the effort for learning debugging is worth it!

Attachment: Debug.jpeg
(Size: 30.56KB, Downloaded 186 times)

[Updated on: Thu, 20 July 2017 18:09]

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Re: How to use the Eclipse Debugger? [message #1768631 is a reply to message #1768627]

Thu, 20 July 2017 18:08

Ed Merks

Messages: 30903
Registered: July 2009

Senior Member

Yes, you should learn the debugger. Once the process is terminated, of you can't debug anymore. Read the tutorial.

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Re: How to use the Eclipse Debugger? [message #1768632 is a reply to message #1768631]

Thu, 20 July 2017 18:16

RajibKumar Bandopadhyay

Messages: 58
Registered: July 2014

Member

I never would have let you repeat your advice twice! You are held in such high esteem!
I have already read the Vogel tutorial, but it is very generalised. It doesn't teach which output codes relate to which errors! There is no tablular data!
I had found other tutorials via Google search by today morning itself, and then on a brainwave tried my idea to find out whether the experienced programmers could identify the errors without looking at the program, but only the errors/outputs!

[Updated on: Thu, 20 July 2017 18:20]

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Re: How to use the Eclipse Debugger? [message #1768634 is a reply to message #1768632]

Thu, 20 July 2017 19:09

Ed Merks

Messages: 30903
Registered: July 2009

Senior Member

No, interpreting a stack trace is like reading tea leaves. One must see the code involved to make sense of it, and even then, often one must reproduce the state of the process at that point in order to actually understand the values of all the variables involved. Things like exception breakpoints (as explained in the tutorial) can be super valuable for that.

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