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