WEBVTT 00:00.050 --> 00:00.710 Hi everyone. 00:00.710 --> 00:01.310 Welcome back. 00:01.310 --> 00:06.350 In this lecture we are going to learn about how do you create a sealed interface and how do we plug 00:06.350 --> 00:08.930 that in into our object oriented design. 00:08.930 --> 00:11.090 So in this case we have this car class. 00:11.090 --> 00:15.470 Now what we are thinking is that most of the cars nowadays are really smart. 00:15.470 --> 00:21.800 So what we need is a smart media player using which you can connect your phone, and then you can play 00:21.800 --> 00:26.930 music, and then you can actually talk to your friends and family through the smart media player. 00:26.930 --> 00:31.640 So what I'm going to do, I'm going to create an interface named Smart Media Player. 00:31.640 --> 00:34.820 And that's going to be a sealed interface okay. 00:34.850 --> 00:36.170 So right click over here. 00:36.200 --> 00:39.740 In this case select the interface over here. 00:39.740 --> 00:43.370 And then I'm going to name this one as Smart Media player. 00:43.370 --> 00:48.170 So this is kind of an interface that can be plugged into any type of vehicle actually. 00:48.170 --> 00:52.820 But in this case I want to implement the smart media player in the car class. 00:52.850 --> 00:53.120 Okay. 00:53.120 --> 00:54.560 Let's go ahead and create this interface. 00:54.560 --> 01:02.520 So I'm going to make this interface sealed because sealed keyword is allowed to be used in the interface 01:02.550 --> 01:03.390 or class. 01:03.390 --> 01:06.840 So far we have seen using sealed with the classes. 01:06.870 --> 01:10.320 Now we are exploring the usage of sealed with the interface. 01:10.320 --> 01:15.240 So in this case I'm going to have this getting implemented in the car class. 01:15.240 --> 01:17.880 So in this case permits car okay. 01:17.910 --> 01:21.390 So I'm going to define a function named connect phone okay. 01:21.420 --> 01:26.070 So any class that implements this interface will have this function available. 01:26.070 --> 01:32.490 So in this case connect phone we can have some additional functions like play music make phone calls 01:32.490 --> 01:33.300 and all those things. 01:33.300 --> 01:35.610 But I'm going to keep this example really simple. 01:35.610 --> 01:37.350 So in this case let's go to the permit class. 01:37.350 --> 01:42.120 So in the permit class we're going to do the implements smart media player. 01:42.150 --> 01:44.130 Now let's look into the compilation issue. 01:44.130 --> 01:48.330 So the compilation issue I believe this needs to come after the instance. 01:48.330 --> 01:51.900 And permits should be the last declaration in this whole thing. 01:51.930 --> 01:52.980 Let's go ahead and add that. 01:52.980 --> 01:56.730 And then let's go ahead and implement the method which is the connect form. 01:56.730 --> 01:56.750 phone. 01:56.750 --> 02:02.240 So in this case we have the connect function which is a connect phone function implemented over here. 02:02.450 --> 02:02.690 Okay. 02:02.720 --> 02:04.340 So I'm just going to print over here. 02:04.340 --> 02:07.400 So it can be like phone connected. 02:10.280 --> 02:13.880 And we can have some additional functionalities added to it. 02:13.880 --> 02:19.160 So this is how you implement a seal interface into your class hierarchy. 02:19.160 --> 02:22.700 So this is very similar to the interface that we normally create. 02:22.700 --> 02:29.210 But by making it sealed you are making sure this particular interface gets implemented on the class 02:29.210 --> 02:31.820 that you defined after the permits keyword. 02:31.820 --> 02:34.040 So I hope the explanation is clear. 02:34.040 --> 02:38.780 If you have any kind of questions or clarifications, you are welcome to write it in Q&A. 02:38.810 --> 02:40.220 I'll be happy to help. 02:40.220 --> 02:43.880 So this wraps up the usage of creating a seal interface. 02:43.880 --> 02:46.370 And how do you incorporate that in your hierarchy? 02:46.400 --> 02:52.610 One key thing to call out is that the permits should be the last block in your whole class definition. 02:52.640 --> 02:54.500 Okay, this marks the end of this lecture. 02:54.500 --> 02:55.550 Thank you for watching.