WEBVTT 00:00.710 --> 00:01.340 Hi everyone. 00:01.340 --> 00:02.620 Welcome back to this tutorial. 00:02.630 --> 00:06.410 In this tutorial, I'll give you all an introduction about optional. 00:06.800 --> 00:14.510 Optional is introduced as part of Java eight and this is used to represent a non null value in Java. 00:15.270 --> 00:21.000 The main purpose of this one is to provide a way to avoid the most common exception, which is the null 00:21.000 --> 00:26.160 pointer exception and avoid having too many null checks in your code. 00:26.190 --> 00:32.730 Any experienced developer would have come across a null pointer exception at some point in their life. 00:35.020 --> 00:42.730 The concept of optional is inspired from the other new languages such as Scala, Groovy and Eccetera. 00:42.760 --> 00:45.940 Let's go ahead and take a look at an example. 00:46.880 --> 00:48.230 Apparently English open. 00:48.230 --> 00:53.450 What I'm going to do, I'm going to create a package called optional. 00:55.790 --> 00:58.430 Package all optional. 00:58.430 --> 01:02.750 And then I'm going to name a class called Optional Example. 01:05.210 --> 01:06.990 Okay, that's good. 01:07.010 --> 01:11.900 Then I'm going to make this class executable by adding public static void main method. 01:16.040 --> 01:21.050 The use case that we are going to code is that I'm going to create a method that is going to return 01:21.050 --> 01:26.750 me a string, which is going to be the name of the student, and then I'm going to print the length 01:26.750 --> 01:28.220 of that name. 01:29.920 --> 01:31.420 So I'm going to create a method here. 01:31.430 --> 01:41.720 The method name is going to be public static, and this is going to return the name of the student and 01:41.720 --> 01:47.090 the return type is going to be string, and the name of the method is going to be get student name. 01:48.520 --> 01:51.470 So I'm going to use the student database class. 01:53.520 --> 01:53.960 Yard. 01:53.970 --> 01:57.240 There is a student supplier which just supplies a student. 01:57.420 --> 01:58.090 Take a look at it. 01:58.110 --> 02:01.430 We are receiving a student called Adam as part of this method. 02:01.440 --> 02:08.010 But this supplier is going to supply the student object and I'm going to call the get method. 02:08.340 --> 02:11.190 So let's consider this one as like a database call. 02:11.190 --> 02:12.690 You're making a database call here. 02:12.690 --> 02:16.230 But actually, behind the scenes, it is just a method which is running the student. 02:16.230 --> 02:20.790 But let's assume this is going to make the database call and then returns the student. 02:20.880 --> 02:21.750 Right. 02:23.250 --> 02:25.260 And let's give it a name. 02:25.920 --> 02:30.060 So if the student is not found, this is going to return null. 02:30.060 --> 02:33.030 So what I'm going to do, I'm going to have the null check here. 02:33.030 --> 02:39.840 If the student is not equal to null, then return. 02:42.100 --> 02:44.890 Student dot getName. 02:45.790 --> 02:46.470 Okay. 02:46.480 --> 02:47.440 Else. 02:48.290 --> 02:49.970 I'm going to return null. 02:50.450 --> 02:53.930 Otherwise, instead of else, I'm going to put the return statement below. 02:55.190 --> 02:56.300 Return null. 02:57.620 --> 03:02.270 Okay, so let's call this method and print the length of the student name. 03:02.300 --> 03:04.430 That's the actual use case, right? 03:04.430 --> 03:05.960 Student Not the student. 03:05.960 --> 03:10.190 It's going to be string name equal to get student name. 03:11.290 --> 03:12.040 Sounds good. 03:12.040 --> 03:16.930 And then what I'm going to do, then I'm going to print the length of the student. 03:17.890 --> 03:21.730 Length of the student name. 03:23.800 --> 03:28.790 In here, what we are going to do, we are going to do name dot length. 03:28.810 --> 03:31.690 This is going to print the length of the student name. 03:31.780 --> 03:33.280 I'm going to run this example. 03:33.430 --> 03:34.150 There you go. 03:34.150 --> 03:35.740 It printed the length as four. 03:35.770 --> 03:41.650 If you go to the student supplier method, this is returning the student name as Adam, and the length 03:41.650 --> 03:43.510 of the name is equal to four. 03:44.580 --> 03:49.770 So what is going to happen is the student is not available in the database, right? 03:49.770 --> 03:52.350 So in that case, we are going to pass null. 03:53.340 --> 03:54.900 And then I'm going to run this program. 03:54.900 --> 03:56.220 Let's see what's going to happen. 03:57.210 --> 04:02.340 So this is going to give me the null pointer exception because I don't have the null check here. 04:02.610 --> 04:08.040 And what I'm going to do, I'm going to add the name not equal to null. 04:08.070 --> 04:09.720 Basically, I'm adding a null check. 04:10.150 --> 04:14.340 So if the name is not equal to null, get the length of the student. 04:14.370 --> 04:20.280 Else you can give name not found. 04:22.050 --> 04:24.000 Name not found. 04:25.110 --> 04:30.960 So now if you take a look at the student, we are having multiple null checks in many places. 04:30.990 --> 04:34.520 Let's say you want to get into the student activities. 04:34.530 --> 04:40.770 Then again, we have to check the length of that student array list and then print the student activities. 04:40.820 --> 04:47.040 So if this object is having many properties and if you want to access each and every property, then 04:47.040 --> 04:53.460 you might have to perform the null check of each and every property and it is going to bloat your code 04:53.460 --> 04:55.110 with all these null checks. 04:55.840 --> 05:00.630 Now we will handle the same scenario using optional and then we'll compare. 05:00.640 --> 05:03.250 What is the difference between these two methods? 05:03.280 --> 05:07.900 These two approaches and what are the advantages of one over the other? 05:08.440 --> 05:13.240 We want to create a method in here. 05:13.840 --> 05:19.120 It's going to be get student name optional. 05:19.330 --> 05:26.050 And in here, what I'm going to do, I'm going to call the optional class dot. 05:26.080 --> 05:31.390 There are many different ways of creating an optional object, but in here I'm going to use the off 05:31.390 --> 05:32.470 nullable method. 05:32.500 --> 05:37.180 We will be covering all these different methods that are part of the option in the future tutorial. 05:37.180 --> 05:41.830 But for now I'm going to use the optional nullable and then I'm going to call this. 05:41.860 --> 05:48.850 Basically what we are doing here is that we are wrapping the actual student object inside the optional 05:48.880 --> 05:49.540 right? 05:49.540 --> 05:55.790 So it's going to be optional of student and then let's give it a name. 05:55.790 --> 05:56.660 Student Optional. 05:56.660 --> 06:03.650 So if you take a look at the code, this code is basically taking this student object actually, and 06:03.650 --> 06:05.540 then wraps it with the optional object. 06:05.540 --> 06:06.650 That's what is happening. 06:08.290 --> 06:08.740 Right. 06:08.740 --> 06:14.470 So how do we check whether this option is having a value or not? 06:14.500 --> 06:21.310 How do we check in this case, whether this object has a optional has a student inside that optional 06:21.310 --> 06:22.090 object or not? 06:22.120 --> 06:28.030 There is a handy method which is available, which is called student optional Dot is present. 06:28.540 --> 06:35.620 This is to check whether is this optional object has any value inside that object or not. 06:35.650 --> 06:40.480 If it is there, what we are going to do, we are going to return the student name. 06:40.480 --> 06:40.710 Right? 06:40.720 --> 06:41.410 That's a use case. 06:41.410 --> 06:42.450 We are coding here. 06:42.460 --> 06:43.930 It is going to return. 06:43.930 --> 06:46.300 Student optional dot. 06:47.090 --> 06:47.570 Map. 06:47.570 --> 06:48.840 There is a handy method called map. 06:48.860 --> 06:51.520 If you take a look at it, there are many methods which are available. 06:51.530 --> 06:57.160 I'll be covering all these methods in the future tutorials, but for now we are going to use a map method. 06:57.170 --> 06:58.160 What do you want to map? 06:58.160 --> 06:59.360 We want to return the name. 06:59.360 --> 06:59.870 Right. 06:59.900 --> 07:04.220 Let's use the method reference syntax and then do the get name. 07:06.160 --> 07:09.220 So this is going to return the. 07:11.730 --> 07:12.750 So the name. 07:12.750 --> 07:20.340 But again, this is going to return the student name inside this optional so optional of type string. 07:20.340 --> 07:24.300 So here the return type is going to be optional of string. 07:24.390 --> 07:30.060 Instead of returning the plain old string, we are going to return the optional of string, which is 07:30.060 --> 07:32.150 going to actually hold the value. 07:32.160 --> 07:35.580 So in here we return the null right in here. 07:35.580 --> 07:40.710 What we are going to do, we are going to return optional of empty. 07:41.680 --> 07:44.110 Basically option of empty represents 07:46.780 --> 07:48.430 an optional object. 07:51.020 --> 07:51.980 But no value. 07:53.210 --> 07:54.620 That's what it represents. 07:55.430 --> 07:58.190 Okay, now I'm going to comment this code. 07:59.950 --> 08:01.060 Let's run this one. 08:02.230 --> 08:08.520 So it's going to return optional of string and let's give it a name. 08:08.530 --> 08:14.770 It's going to be string optional equal to get student name optional. 08:14.860 --> 08:17.410 So that's the method which we are going to call. 08:20.510 --> 08:29.300 So like how we perform the not null check we are going to perform string optional dot is present. 08:29.810 --> 08:32.030 If it is present, then get the name. 08:32.030 --> 08:33.800 So how do we get the actual value? 08:33.800 --> 08:39.250 The way to get it is by using string optional dot get. 08:39.260 --> 08:43.340 So in here we use a map method to get to the actual name of it. 08:43.340 --> 08:48.550 If you want to just get the student object itself, then you can call the get method. 08:48.560 --> 08:50.090 This will return the. 08:50.870 --> 08:51.680 Didn't object. 08:52.340 --> 08:58.490 Then Here, this will return the string, which is student name. 08:59.900 --> 09:00.350 Okay. 09:00.350 --> 09:01.910 And then what do you want to do? 09:01.910 --> 09:04.550 We want to calculate the length of the student. 09:04.550 --> 09:05.120 Right. 09:05.690 --> 09:09.680 Let's copy this code here and then put it here. 09:10.460 --> 09:13.580 So here we are, printing the length of the student name. 09:13.580 --> 09:16.430 Let's run this code and then check the result. 09:17.810 --> 09:21.020 If you take a look at it, the length of the student name is four. 09:22.570 --> 09:23.910 If it is not present. 09:23.910 --> 09:27.990 What we want, what we want to do in the case of else, we will provide. 09:29.510 --> 09:30.530 Name not found. 09:32.750 --> 09:33.230 Right. 09:33.230 --> 09:34.430 Let's run this and check. 09:35.700 --> 09:39.550 You run it, it's going to give you the length of the student of the name. 09:39.580 --> 09:41.760 Length of the student name, actually. 09:41.760 --> 09:46.530 And then what I'm going to do here, let's change this. 09:46.860 --> 09:52.140 Let's change this code to return the option of nullable. 09:53.660 --> 09:54.380 What are the values? 09:54.600 --> 09:55.920 What this is going to do. 09:55.920 --> 09:59.700 This is going to return optional dot empty. 10:00.510 --> 10:07.350 So when this code runs, when this is present, check is run, basically this is going to return false 10:07.350 --> 10:11.730 and then we are going to return the actual object. 10:11.730 --> 10:13.440 So instead of returning this, we can do this. 10:13.440 --> 10:19.080 Also, we can return the student optional or if we need the optional dot string, right? 10:19.080 --> 10:21.030 So this represents optional of student. 10:21.030 --> 10:28.710 So in here, when we pass null what it is going to return, it is going to return optional dot empty 10:28.980 --> 10:33.600 when this check runs for the empty optional object this is going to. 10:34.630 --> 10:38.960 Evaluate to false and then it is going to return optional empty. 10:39.010 --> 10:40.780 And in here, what is going to happen? 10:40.780 --> 10:48.520 This is going to this is going to evaluate to false and then it is going to print name not found. 10:48.640 --> 10:51.460 Let's run this and check if we take a look at it. 10:51.460 --> 10:53.280 That's the result we got. 10:53.290 --> 10:55.450 So you might be wondering what's the difference here? 10:55.450 --> 10:56.050 Right. 10:56.290 --> 11:00.760 Let me move away from the presentation mode so that I can show you the whole code. 11:00.790 --> 11:07.840 So in here, if you take a look at it, this method is returning null and this method is returning option 11:07.840 --> 11:08.620 dot empty. 11:08.650 --> 11:11.230 So we replaced not null. 11:11.230 --> 11:13.180 Check with the is present check. 11:13.300 --> 11:13.840 Right. 11:13.840 --> 11:15.130 That might be running in your mind. 11:15.130 --> 11:16.260 What is the difference here? 11:16.270 --> 11:23.740 The difference between the null and optional here is that you can still execute a method call on an 11:23.740 --> 11:25.000 empty optional object. 11:25.000 --> 11:31.600 So in here, even though this get student name optional returns empty, you will still be able to check 11:31.600 --> 11:39.560 whether that value inside that optional object is present or not on that empty optional object and the 11:39.560 --> 11:44.990 return type of this method here, if you take a look at it, the return type is here we are returning 11:44.990 --> 11:47.420 null null doesn't belong to any type. 11:47.420 --> 11:51.500 Anything can be null, a string can be null, the student object can be null. 11:51.650 --> 11:59.180 But in the case of this method, it is always going to return the optional type optional as a support 11:59.180 --> 12:03.680 for a lot of additional methods which can be used for variety of use cases. 12:03.680 --> 12:10.280 We will be exploring all those methods in the following tutorials, but for now this is all about optional. 12:10.460 --> 12:13.280 Let's talk about more different scenarios in the future. 12:13.280 --> 12:14.090 Tutorials. 12:14.090 --> 12:16.130 With this we came to the end of this tutorial. 12:16.160 --> 12:17.270 Thank you for watching.