Netbeans/C2/Netbeans-Debugger/English-timed

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Time Narration
00:01 Hii everyone.
00:02 Welcome to the tutorial on Netbeans Debugger.
00:06 If this is the first time you are using Netbeans, please view the earlier tutorials on the Spoken Tutorial website.
00:14 For this demonstration, I am using the Linux Operating System Ubuntu v12.04,
00:21 and Netbeans IDE v7.1.1
00:26 We all know that debugging programs can be a rather painstaking task.
00:31 Hence, knowing a debugging tool and being familiar with its features can help you save valuable time.
00:39 This powerful debugging tool is very useful,
00:42 especially when you have to code or test large programs.
00:46 In this tutorial we will learn some of the features that the Netbeans Debugger provides.
00:53 This tutorial will acquaint you with
00:55 the debugging window


00:58 configuring breakpoints
01:00 evaluating expressions or setting watches


01:04 options for tracing the execution of your program


01:17 and options to configure the debugger itself


01:12 Now Let's get started and debug this sample code.
01:17 I will switch to the Netbeans IDE


01:20 I have already created a Java Application, sampleDebug in my IDE for this demonstration.
01:27 This is a small program that initializes three integer values a, b, and c.


01:35 Then it prints 'Hello World!' and the value of 'a'.
01:40 It also creates a class object 'SampleClass', which has a 'value' integer, as a private integer value.
01:52 Then, it computes the value of 'b' ,
01:55 and calls a function to compute the value of c,


02:00 and prints the values of 'b' and 'c'.


02:05 To start with the debugging, let us first set the breakpoint.
02:09 To set a breakpoint, click on the line number.
02:13 I will set at this line which prints Hello World!


02:18 Notice that the line at which a breakpoint is set changes it's colour to pink and is marked by a small square against its line number.
02:28 When you run the program in the debugging mode,
02:31 by clicking on the Debug Project button in the toolbar,
02:35 the execution of the program stops at the line at which the breakpoint is located.
02:41 So far, 'a's value has been set.
02:45 Hover on it to check it's value.


02:49 It indicates that it's value is 10.


02:52 You can see that there are some additional windows below the workspace.
02:59 There is a 'Variables' window that shows a list of variables and their values.


03:07 So far, only the variable 'a' has been initialized.


03:11 We can also look at the 'Output' window with the sample debug output.


03:17 There is no output yet.


03:19 There is also a 'Debugger Console' ' that says that the program hit a breakpoint on line 29 and has stopped there.


03:28 There is also a 'Breakpoints' window that tells you that a breakpoint has been set on line number 29.


03:36 Before proceeding, let us see how to add a watch.


03:40 For example, let us say I want to watch on the integer value 'aSample'.


03:48 In the 'Variables' window below the workspace, I will double-click on the Enter new Watch option and enter the name of the variable 'aSample.value'.


04:02 Click on OK.


04:06 So far 'aSample' has not been created so it says it does not know the value.


04:12 Once it executes the line we'll know what the variable contains.



04:16 In a similar way you can also watch and evaluate expressions.


04:21 Here I'm checking for b=a+10.


04:25 What if I wanted to know what a-4 is.
04:29 So let me go to the Debug menu in the menu bar, and select Evaluate expression option.
04:37 The 'Evaluate Code' window appears in the workspace.
04:41 Here I will enter the expression 'a-4'.
04:45 Click on the Evaluate Expression button here, and in the Variable window, it says 'a-4' s value is 6.
04:56 Let us now proceed and execute this single line of code.
05:00 To do that, choose the Step-Over button from the toolbar.


05:06 That should execute only that 1 single line of the code to print “Hello World”.
05:12 To see the output, go to the output window and choose the sampleDebug output window


05:17 That says, Hello World! a is 10.


05:22 The program has now stopped at the line to create a SampleClass object.
05:28 Now, I want to go into the constructor of the SampleClass.
05:32 To that I can choose the Step Into option from the toolbar.


05:41 Then I can choose Step Over and see that the value came inside the constructor call is now set to 10.
05:51 You can also check that by hovering on the variable.
05:55 When I Step Over again, we can see that this.variable is also set to 10.


06:03 To get out of this function I can either choose Continue, Step Over or Step Out.


06:11 Let me choose Step-Out to come out of the method.
06:14 And now I'm back to where the function call was made.
06:19 When I say Step-Over again, you will notice that aSample.value is now set to10.
06:27 This is what we were watching for.
06:30 Apart from Breakpoints and StepOvers, you can also stop the execution of the program at the line of the cursor.
06:38 For example, let me go into the function here and set the cursor to be on this line which says d=b-5; .


06:49 Now from the toolbar, choose the Run To Cursor option.
06:54 You will notice that the execution of the program gets into the function and stops at the line where the cursor is located.
07:05 You can see that it has computed the value of b, as 20.
07:10 And inside the variable window, it has set 'b' to be 20.
07:14 Now, I can choose Step Over again and d's value also gets initialized and becomes 15.
07:23 Now, I can either choose to return or completely finish the execution of the program.
07:29 Let me choose Step Out and come back to the function call.


07:36 When you hover on the getC() function, you'll notice that the function has returned a value of 15.
07:43 The variable 'c' has not yet been assigned that value.
07:47 So, when we Step Over and execute that line, 'c' will get a value of 15.


07:55 We can now check it in the variable window or hover on the variable to check it's value.
08:03 Now if you want to stop the debugging session, you can choose the Finish Debugger Session option from the toolbar.
08:12 If you want to continue the execution to the next breakpoint you can choose the Continue option.
08:19 Once you finish, you can also choose the Continue option to complete the execution of the remaining program.
08:25 Let me choose Continue here.
08:27 In the Output window, it shows me the output as: b is 20 and c is 15.
08:34 Now, this was a quick overview of the options of debugging on netbeans.


08:39 If you want any advanced feature settings, you can -


08:42 Go to Tools menu, click on Options, go to Miscellaneous option, click on the Java Debugger tab.


08:53 Here you can change settings for multi-threaded program breakpoint options.
08:59 Or have filters to decide on which methods you would want to step in.
09:07 Now to the assignment.
09:09 As an assignment, take any of your programs, excellent if it has already errors.
09:16 If not, introduce some errors with the logic or algorithm.
09:20 Set breakpoints in the code. Usually, you would set a break at the calling point of a function which you suspect has the error.
09:29 Use Step-Into to go into the function.
09:32 Use Step-Overs to execute the lines and make sure to inspect the values of variables in the variable window.


09:41 Add some watches to help you identify and correct the error.


09:45 Step-Out of the method.
09:48 Continue till you reach the next breakpoint.
09:51 And finally, Finish the debugger session and Run your application.
09:57 In this tutorial, we became familiar with the netbeans debugger.
10:02 We saw how to set breakpoints and watches.
10:06 Add expressions which we want to evaluate, while the code is running.
10:11 Trace execution of a program with Step-Into, Step-Over, Step-Out and Run-to-Cursor options.
10:19 Also saw how to configure the debugger for advanced debugging.
10:24 Hope this tutorial saves you a lot of time in your testing and debugging tasks.


10:30 Watch the video available at the link shown on the screen.
10:33 It summarizes the Spoken Tutorial project.
10:36 If you do not have good bandwidth, you can download and watch it
10:41 The Spoken Tutorial project team conduct workshops using Spoken Tutorials.


10:46 Gives certificates to those who pass an online test.


10:49 For more details contact contact@spoken-tutorial.org


10:55 Spoken Tutorial Project is a part of the Talk to a Teacher Project
10:59 It is Supported by the National Mission on education through ICT, MHRD, Government of India
11:05 More information on this mission is available at spoken-tutorial.org/NMEICT-Intro
11:14 This tutorial has been contributed by IT for Change


11:18 Thank you for joining us.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14