Netbeans/C2/Netbeans-Debugger/English-timed

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Time Narration
00:01 Hello everyone.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 version 12.04
00:21 and Netbeans IDE version 7.1.1.
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 and
01:07 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 break-point.
02:09 To set a break point, click on the line number.
02:13 I will set it at this line which prints "Hello World!".
02:18 Notice that the line at which a break-point 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, as 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 sampleDebug 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 do that, I can choose the Step Into option from the toolbar.
05:41 Then I can choose the 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 over 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 to 10.
06:27 This is what we were watching for.
06:30 Apart from Breakpoints and Step Overs, 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 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 the 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 the 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: * conducts 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