WEBVTT 00:00.080 --> 00:00.620 Hi everyone. 00:00.620 --> 00:01.340 Welcome back. 00:01.370 --> 00:06.950 In this lecture we are going to look into the behavior of the superclass, which is the vehicle class 00:06.950 --> 00:08.990 by making it an abstract class. 00:08.990 --> 00:12.050 So what I'm going to do I'm going to add the abstract behavior here. 00:12.080 --> 00:12.680 There you go. 00:12.680 --> 00:15.050 And then I'm going to define a function named drive. 00:15.080 --> 00:21.020 So in this case let's go ahead and add public abstract string and then drive. 00:21.050 --> 00:25.940 So I'm hiring a function named drive which is common across all vehicles okay. 00:25.970 --> 00:31.130 So now as soon as you add this the car class and the truck class are going to have compilation issues 00:31.130 --> 00:33.800 because they need to implement the drive function there. 00:33.800 --> 00:37.370 So in this case let's go ahead and implement the method. 00:37.910 --> 00:38.510 There you go. 00:38.510 --> 00:42.770 So the drive function is going to return what type of vehicle it is driving. 00:42.770 --> 00:44.780 So in this case it is a car okay. 00:44.810 --> 00:47.600 We'll go ahead and do the same thing for the truck one two. 00:47.630 --> 00:50.690 So in this case let's go ahead and implement the method. 00:51.170 --> 00:53.990 And in this case we are going to return the truck. 00:55.100 --> 01:00.260 So what we are learning is that what is the effect of adding this abstract keyword to the vehicle class 01:00.260 --> 01:02.630 and the effect of the same in the subclasses. 01:02.630 --> 01:07.280 So the effect of the abstract keyword is similar to any other regular class. 01:07.280 --> 01:11.960 So if you add a class abstract and if you add an abstract function, all the classes that's extending 01:11.960 --> 01:15.140 this vehicle class need to provide an implementation. 01:15.140 --> 01:17.300 That's exactly what we did over here. 01:17.300 --> 01:22.520 So it is a common practice to provide some abstract methods in a sealed abstract class, and then have 01:22.520 --> 01:25.100 those behaviors implemented in the subclasses. 01:25.130 --> 01:27.890 Now what we will do, we'll go ahead and write some test cases. 01:27.890 --> 01:30.710 So what I'm going to do, I'm going to create the test case. 01:30.710 --> 01:32.600 I'm going to name this one as drive okay. 01:32.630 --> 01:36.290 So we already have these instance checks successfully passing. 01:36.290 --> 01:39.800 Now the next thing is we are going to check what is the drive function. 01:39.830 --> 01:41.360 Assertion returns okay. 01:41.390 --> 01:43.550 So in this case let's do assert equals. 01:43.550 --> 01:44.180 There we go. 01:44.180 --> 01:46.160 So hard drive what does it return. 01:46.190 --> 01:49.580 So in this case the car drive is going to return you a car. 01:49.610 --> 01:49.940 Right. 01:49.970 --> 01:52.160 So that's what we are actually returning over here. 01:52.160 --> 01:54.740 So if you go and take a look at it that's what it returns. 01:54.740 --> 01:56.720 Let's copy this and then put this over here. 01:56.720 --> 02:01.400 And then similarly for the truck to drive what does it return. 02:01.400 --> 02:03.980 So the truck dot drive return the truck. 02:04.010 --> 02:04.460 Right. 02:04.490 --> 02:06.980 Let's copy this and then put it over here. 02:07.010 --> 02:07.610 There you go. 02:07.640 --> 02:09.680 Now let's go ahead and execute this test case. 02:09.680 --> 02:13.040 So this test case should succeed without any issues. 02:14.660 --> 02:15.260 There you go. 02:15.260 --> 02:17.000 The test case gave us a green check. 02:17.030 --> 02:19.220 That means it is working as expected. 02:19.220 --> 02:24.860 So basically what I wanted to show you is that by making the Seal class abstract, the behavior of the 02:24.860 --> 02:30.920 abstract class is going to be very similar to applying the abstract class of a regular class. 02:30.920 --> 02:32.570 I hope the explanation is clear. 02:32.570 --> 02:35.750 I do understand this is a very naive and simple example. 02:35.750 --> 02:40.790 As I mentioned, there is a dedicated section where we are going to implement a real time example. 02:41.120 --> 02:46.460 I just wanted to keep this examples really simple and naive, so that it is pretty easy to grasp these 02:46.460 --> 02:50.150 concepts that you can use to implement a real time example. 02:50.150 --> 02:51.620 Well, this marks the end of this lecture. 02:51.620 --> 02:52.760 Thank you for watching.