WEBVTT 00:00.140 --> 00:00.770 Hi everyone. 00:00.770 --> 00:01.340 Welcome back. 00:01.340 --> 00:04.490 In this lecture we will learn about the record classes. 00:04.520 --> 00:07.940 I will start with some theory first and then we will get to the coding part. 00:07.970 --> 00:14.030 Record class is a special type of class with a record keyword in it, instead of the class keyword that 00:14.030 --> 00:16.340 we normally use to create classes. 00:16.340 --> 00:23.510 They are immutable data holders, which means the primary goal and intention of record classes is to 00:23.540 --> 00:24.830 just hold the data. 00:24.830 --> 00:28.310 So here is an example of how a record class would look like. 00:28.310 --> 00:31.160 So in this case we have a record class named product. 00:31.160 --> 00:35.570 And you can notice there is a record keyword in it instead of the class keyword. 00:35.570 --> 00:42.500 And followed by that we have the open and close parentheses which holds a field that product is going 00:42.500 --> 00:43.490 to represent. 00:43.490 --> 00:47.960 We have three fields here name, cost and type to represent the product. 00:47.960 --> 00:54.590 But in reality there can be many more fields to represent a product that a user is interested in buying. 00:54.590 --> 00:58.910 So the final version of the record class is available from Java 17. 00:58.910 --> 01:01.430 Let's say your code runs on Java 17. 01:01.460 --> 01:05.510 Then you already have the record feature available for you to use. 01:05.510 --> 01:11.750 And one important thing to call out is that record classes are final, which means no inheritance is 01:11.750 --> 01:13.850 supported on the record classes. 01:13.880 --> 01:19.880 And the record classes also have auto generated equals, hashCode and toString functions. 01:19.880 --> 01:26.240 The idea is to make sure the class looks light, and the intention of the class is to behave as data 01:26.270 --> 01:32.240 holders, but the auto generated functions is pretty easy to do the equality check without the need 01:32.270 --> 01:33.950 to write any complex logic. 01:33.950 --> 01:38.330 So with this information, let's go ahead and look into the record classes in action. 01:38.330 --> 01:41.510 So I'm going to switch back to IntelliJ and start coding this one. 01:41.540 --> 01:42.950 There you go I'm back in IntelliJ. 01:42.980 --> 01:46.820 So we are going to be working on the Explore latest Java Features project. 01:46.820 --> 01:50.630 So in this case I'm going to create a package named Record or Records. 01:50.630 --> 01:53.000 And then I'm going to create a class named product. 01:53.000 --> 01:56.180 So you create the record class as like a regular class. 01:56.180 --> 02:01.220 So you select the Java class option, but in the place of this pop up window, you select the option 02:01.220 --> 02:02.240 as record, okay? 02:02.270 --> 02:04.580 And then we provide the value as product. 02:05.060 --> 02:05.990 There you go. 02:05.990 --> 02:10.460 So in the product what we are going to do, we are going to be providing the three fields that we saw 02:10.490 --> 02:11.600 in the slide. 02:11.600 --> 02:14.720 So in this case number one is going to be string name. 02:14.720 --> 02:17.450 And the next one is going to be the cost. 02:19.220 --> 02:23.090 And then the next one is going to be string type okay. 02:23.120 --> 02:26.120 So this is a very simple representation of the product. 02:26.120 --> 02:28.400 So we have the record class ready. 02:28.430 --> 02:30.380 Now it's time to test this one out. 02:30.380 --> 02:33.350 So what I'm going to do I'm going to be creating a product test. 02:33.350 --> 02:38.450 And then try to create an instance of product and try to access these properties in it. 02:38.450 --> 02:41.120 So in this case let's go ahead and create a test. 02:41.120 --> 02:44.330 So in this case I'm going to create a test named Product Test. 02:44.390 --> 02:45.380 Click on that one. 02:45.410 --> 02:47.360 And then I'm going to put this on the right. 02:49.550 --> 02:51.560 So what we need is a test case right. 02:51.590 --> 02:53.390 So let's go ahead and create a test case. 02:53.570 --> 02:54.440 There you go. 02:54.440 --> 02:57.950 So in this case I'm going to name the test case as create product. 02:57.980 --> 03:01.040 So in this case it's going to be create product. 03:01.070 --> 03:01.940 There you go. 03:01.940 --> 03:05.240 And what we are going to do is we are going to be creating a new product. 03:05.240 --> 03:09.410 So where product equal to new product. 03:09.410 --> 03:13.250 And then pass the name as I'm going to create a product named iPhone. 03:13.250 --> 03:17.180 And then I'm going to pass the cost as a new Bigdecimal. 03:17.180 --> 03:20.360 So in this case it's going to be new Bigdecimal. 03:20.360 --> 03:25.580 And then we're going to be passing the value as 999.99. 03:25.580 --> 03:28.070 And then I'm going to pass the type as electronics. 03:28.100 --> 03:31.100 So in this case it's going to be electronics. 03:31.910 --> 03:32.360 Okay. 03:32.390 --> 03:34.100 So we have the product created. 03:34.130 --> 03:37.040 The next step is what can we do with this product instance. 03:37.040 --> 03:40.700 So let's say I want to just print this value so we can do a product. 03:40.730 --> 03:41.330 There you go. 03:41.330 --> 03:45.170 And other questions that I have in my head is how do I access this one. 03:45.170 --> 03:51.710 But predominantly if you have used domain classes, either you will have a complete implementation of 03:51.710 --> 03:57.520 the getter and setter methods, or you might have used a library like Lombok in Java to auto generate 03:57.520 --> 03:58.330 those classes. 03:58.330 --> 04:03.430 So in this case, if you do a product dot, what you have is name cast and type. 04:03.430 --> 04:05.080 So these are the accessors. 04:05.080 --> 04:09.820 So these are the functions which give you access to those values for these fields. 04:09.820 --> 04:15.400 And you can see there is no setter function which means the record classes are immutable. 04:15.400 --> 04:18.940 Once it's created there is no way that you can edit that value. 04:18.940 --> 04:22.030 So what I'm going to do is I'm going to perform some assertions. 04:22.030 --> 04:23.710 So I'm going to call the name. 04:23.710 --> 04:28.360 So I'm going to do assert equals assert equals. 04:28.360 --> 04:31.270 And then the expected name is going to be. 04:33.400 --> 04:34.090 iPhone. 04:34.090 --> 04:36.190 So I'm going to provide that value over here. 04:37.180 --> 04:37.840 There you go. 04:37.840 --> 04:41.800 And then similarly for the type it's going to be electronics. 04:42.490 --> 04:45.580 It's going to be type okay. 04:45.610 --> 04:47.890 So now let's go ahead and execute this program. 04:49.660 --> 04:54.040 So after we executed this test let's go ahead and quickly look into the console. 04:54.040 --> 04:55.480 So in the console you see right. 04:55.480 --> 04:58.840 So this two string is automatically generated for you. 04:58.840 --> 05:05.140 The only reason why this is available to us is because we defined the class as record type. 05:05.140 --> 05:10.330 So when you define the class as record type, it gives you access to the two string and it automatically 05:10.330 --> 05:11.560 constructs this for you. 05:11.590 --> 05:16.660 I hope you all were able to successfully create a record and how to construct a record. 05:16.660 --> 05:20.110 And how do you access the properties that are part of the record in the next lecture? 05:20.110 --> 05:23.380 What I'm going to do is I'm going to show you some advanced concepts. 05:23.380 --> 05:24.910 Let's try to record meaning. 05:24.910 --> 05:27.340 How do you perform the property validations? 05:27.340 --> 05:33.010 Let's say you don't want to have an empty value as a product name, and you don't want the cost to be 05:33.010 --> 05:34.240 in a negative value, right? 05:34.240 --> 05:39.730 So all those validations can be applied before constructing the actual product instance. 05:39.730 --> 05:41.830 Let's look into those concepts in the next lecture. 05:41.830 --> 05:46.570 Before I wind up this lecture, I would like to quickly provide a summary of what we have learned. 05:46.750 --> 05:52.660 I want to specifically cover the summary by explaining the benefits of using the record classes. 05:52.660 --> 05:58.840 So with the introduction of record, the domain classes in Java can be represented in simpler form. 05:58.840 --> 06:02.740 Because record concept is part of the language itself. 06:03.010 --> 06:08.230 With the record classes, we don't have to write the boilerplate code for the domain classes. 06:08.260 --> 06:13.030 This involves constructors getter, setter, hashCode, equals, and toString. 06:13.030 --> 06:19.210 All these are automatically available for you if you define your domain classes with a record type. 06:19.240 --> 06:25.900 This also avoids the need to rely on other libraries, such as Lombok to represent the domain classes, 06:25.900 --> 06:28.930 and it's an alternative way to tackle the verbosity. 06:28.930 --> 06:34.840 So the main concern that we are addressing as part of records is that code verbosity is a common complaint 06:34.840 --> 06:38.920 by Java developers for creating and managing domain classes. 06:38.950 --> 06:45.040 Record classes does a good job of handling it, and makes it a favorable choice to represent the domain 06:45.040 --> 06:45.730 classes. 06:45.730 --> 06:47.560 With this, we came to the end of this lecture. 06:47.560 --> 06:48.700 Thank you for watching.