WEBVTT 00:00.050 --> 00:00.620 Hi everyone. 00:00.620 --> 00:01.850 Welcome back in this lecture. 00:01.850 --> 00:06.290 What we are going to learn is that we are going to learn the object equality when you are dealing with 00:06.320 --> 00:07.370 record classes. 00:07.610 --> 00:14.450 Because if you all can recall in the slide I mentioned the record classes by default generate the hashCode 00:14.450 --> 00:15.980 equals toString function. 00:15.980 --> 00:20.450 We have looked into the toString function, but we have not looked into the equality check yet. 00:20.450 --> 00:22.880 So that is what we are going to explore in this one. 00:22.880 --> 00:26.180 So in this case what I'm going to do I'm going to create a test case. 00:26.180 --> 00:29.840 So I'm going to name this one as Create product comparison okay. 00:29.870 --> 00:34.880 So what I'm going to do I'm going to create new product named product one okay. 00:34.910 --> 00:36.890 So if you want to add the type you are welcome to do it. 00:36.890 --> 00:40.010 So what I'm going to do I'm going to add the type as electronics. 00:40.010 --> 00:42.110 And I'll do the same thing over here. 00:43.550 --> 00:45.380 Oops I made a mistake. 00:46.970 --> 00:47.720 There you go. 00:47.750 --> 00:50.330 And we'll do the same thing for the other one too. 00:50.360 --> 00:53.990 So if I do a equality check how is this going to work. 00:53.990 --> 01:00.260 So what I'm going to do, I'm going to be calling assert equals and then pass the product comma product 01:00.260 --> 01:00.740 one. 01:01.010 --> 01:02.840 So we are passing these two products. 01:02.870 --> 01:03.230 Right. 01:03.260 --> 01:09.140 What we are expecting is that each and every property which is iPhone, the cost and the electronics 01:09.140 --> 01:10.940 will be compared against each other. 01:10.940 --> 01:13.450 and that's how it performs a quality check. 01:13.450 --> 01:18.670 But all these functions are automatically created for you behind the scenes when you create a class 01:18.670 --> 01:19.360 with record. 01:19.360 --> 01:22.720 So now if I execute this one, you're going to see a green signal. 01:22.720 --> 01:25.840 This means the product comparison is worked okay. 01:25.870 --> 01:30.910 So in order to break this what I'm going to do I'm going to change this value to electronics one, just 01:30.910 --> 01:33.370 to show you the actual impact of this one. 01:33.370 --> 01:35.680 So in this case let's go ahead and execute this one. 01:35.680 --> 01:37.690 So you'll be able to see the error right. 01:37.690 --> 01:41.440 So the error says expected was electronics one. 01:41.440 --> 01:44.320 But the actual value that is expected is electronics. 01:44.320 --> 01:49.090 So it clearly compares each and every property that is part of the record class. 01:49.120 --> 01:50.620 Now what are the options. 01:50.620 --> 01:53.260 Let's say you don't want to check all the properties. 01:53.260 --> 01:54.550 That's part of the record class. 01:54.550 --> 01:58.270 You want to check only the few properties that are part of the record class. 01:58.270 --> 02:03.460 In this kind of scenarios, we can actually very well override the hashCode and equals function. 02:03.460 --> 02:06.970 So in this case type in equals and press enter. 02:07.000 --> 02:09.850 The IntelliJ has a way to automatically generate this for you. 02:09.850 --> 02:12.760 And then select this option that's been shown to you. 02:12.760 --> 02:15.130 And then press next over here. 02:15.130 --> 02:16.300 And then it's going to check. 02:16.300 --> 02:20.110 Hey these are the different properties that you want to apply equals against. 02:20.110 --> 02:25.070 I'm just going to select as it is, and then we can modify it once we have the implementation ready. 02:25.070 --> 02:30.140 And then it is going to ask you is hashCode also needed for all these different properties. 02:30.140 --> 02:31.430 And then click create. 02:31.430 --> 02:37.040 So this is the functionality that is automatically generated for you by our IntelliJ. 02:37.070 --> 02:38.360 So in this case you can see right. 02:38.360 --> 02:41.330 So we have the product name comparison first. 02:41.330 --> 02:43.280 And we have the cost comparison next. 02:43.280 --> 02:44.900 And then the type comparison. 02:45.230 --> 02:45.530 Okay. 02:45.560 --> 02:50.150 So let's say we decide okay I don't want to have type as part of the equality check. 02:50.150 --> 02:53.870 All you got to do is actually comment out this code in your equals function. 02:53.870 --> 02:58.940 And then if you go and change this one to electronics one, and then if you still try to execute this 02:58.940 --> 03:01.490 particular test case this will still succeed. 03:01.490 --> 03:05.810 The reason being we have removed the type out of the equality check. 03:05.810 --> 03:11.780 So this is how you override the equals and hashcode function in a record class. 03:11.780 --> 03:16.370 So the default behavior is the record classes are going to compare each and every property. 03:16.370 --> 03:22.610 But if you want to override that property or override that functionality you have these options available. 03:22.640 --> 03:23.810 I hope this makes sense. 03:23.840 --> 03:29.060 I hope you all have a pretty good idea about how equality checks work in record classes. 03:29.090 --> 03:30.560 This marks the end of this lecture. 03:30.560 --> 03:31.580 Thank you for watching.