WEBVTT 00:00.320 --> 00:00.960 Hi everyone. 00:00.960 --> 00:01.560 Welcome back. 00:01.560 --> 00:07.200 In this lecture we will code and learn about how unnamed variables can work alongside with pattern matching. 00:07.200 --> 00:10.000 So in this case let's open the record match over here. 00:10.000 --> 00:12.040 And let's go to the animal service class. 00:12.240 --> 00:18.200 So in the animal service class as you can see until Java 21, if you are not using this particular variable 00:18.440 --> 00:20.880 you still need to declare this variable. 00:20.920 --> 00:23.880 Otherwise the compiler will have an issue with that. 00:23.880 --> 00:27.680 But with the unnamed variables, we don't have to do this anymore. 00:27.680 --> 00:29.800 So I'm going to be putting it over here. 00:29.800 --> 00:34.120 And then I'm renaming this to be with unnamed variables. 00:34.440 --> 00:40.560 So what we can do now is basically we can actually add underscore and the code will not complain at 00:40.560 --> 00:41.280 all okay. 00:41.320 --> 00:43.520 So and then we can also use it guarded. 00:43.520 --> 00:44.720 That's missing over here. 00:44.720 --> 00:50.080 So in this case when name equal to equal to null then just return empty string. 00:50.120 --> 00:50.480 Right. 00:50.520 --> 00:52.760 And in the case of this you can see the compilation issue. 00:52.760 --> 00:53.080 Right. 00:53.080 --> 00:55.240 Hey you are just handling the null condition. 00:55.400 --> 00:58.440 If it's not null you need to still handle that condition also. 00:58.440 --> 01:03.540 So if you're going to be not null, then in that case we are going to be adding this over here. 01:03.580 --> 01:04.060 There you go. 01:04.060 --> 01:06.500 So this is the benefit of using a grid pattern. 01:06.540 --> 01:12.820 Here you can actually add this underscore which is the representation of unnamed variable where this 01:12.820 --> 01:15.180 variable is not going to be used at all. 01:15.180 --> 01:17.100 That's what the underscore is for. 01:17.140 --> 01:22.420 So now with the help of the coding assistant we are going to be writing the test for this one. 01:22.420 --> 01:24.540 So let's go ahead and look at some of the test. 01:24.980 --> 01:26.100 Let me move this to the right. 01:26.140 --> 01:26.620 There you go. 01:26.620 --> 01:30.220 So now I'm going to ask the assistant to write a test for me. 01:30.260 --> 01:35.380 So in this case we are actually going to be focusing on the animal service class. 01:35.700 --> 01:40.260 I'm going to ask it to please write a test for this function. 01:40.300 --> 01:44.060 I'm going to just highlight this one in the animal service test. 01:44.060 --> 01:49.340 And I'm also using the agent mode so that it can go ahead and identify what the classes and write the 01:49.340 --> 01:50.060 test for me. 01:50.620 --> 01:55.900 And in my experience, I'm pretty much using the agent mode wherever possible so that it has the ability 01:55.900 --> 01:59.620 to read the code base, understand the context, and make the changes for me. 01:59.620 --> 02:02.460 So in here I'm expecting it to write a test case over here. 02:02.500 --> 02:08.630 Press enter over here so it tells me that I'll help you write a test for retrieve name using guard pattern 02:08.630 --> 02:10.150 with unnamed variables function. 02:10.150 --> 02:12.230 So it's first analyzing this particular class. 02:12.990 --> 02:15.910 As you can see, it created a test for me. 02:15.910 --> 02:20.590 So it's identified like I see there is already a test present for this one. 02:20.590 --> 02:22.790 And it actually added all these scenarios. 02:22.830 --> 02:23.070 Right. 02:23.070 --> 02:29.790 So because in our case this guarded pattern have a different condition checks, we have a null if the 02:29.790 --> 02:31.790 name is null we handle it differently. 02:31.790 --> 02:34.830 If the name is not null we handle it differently. 02:34.830 --> 02:35.310 Right. 02:35.310 --> 02:37.950 So now it added all these things in this way. 02:37.950 --> 02:43.030 This looks like we have multiple assertions happening, but the coding looks very verbose. 02:43.070 --> 02:47.310 Actually the test case looks verbose, so I'm going to ask it to use this pattern. 02:47.310 --> 02:51.870 Hey, why don't you use use the add method source syntax. 02:52.150 --> 02:54.070 Let's see what the changes it's going to do. 02:54.070 --> 02:57.710 Because we already have a pattern over here right. 02:57.710 --> 03:03.190 So in this case it basically tried to use the same functionality that's been used by this particular 03:03.190 --> 03:03.830 test. 03:03.830 --> 03:06.410 And then now it's working as expected Okay. 03:06.450 --> 03:09.170 So now let's go ahead and run this particular test case. 03:11.450 --> 03:11.650 Okay. 03:11.690 --> 03:13.530 The test case is working as expected. 03:13.530 --> 03:16.650 But in my case I want the name to be null. 03:16.650 --> 03:18.730 If it's null, I'm returning an empty string. 03:18.730 --> 03:19.410 Right. 03:19.410 --> 03:23.250 So I want to make further changes to this particular test. 03:23.450 --> 03:26.850 I'm going to ask the agent to look for the change and make the change. 03:27.250 --> 03:30.530 The input to this function can have a null name. 03:30.650 --> 03:32.610 Can you add the check to this test? 03:32.610 --> 03:37.650 And one important thing to call out is that this input function is being used by the other test cases 03:37.650 --> 03:38.330 also. 03:38.330 --> 03:42.890 So what I'm going to ask it to do is do not reuse the input function. 03:42.890 --> 03:49.130 Please add a new one for this test so that the other tests are not going to be impacted. 03:49.130 --> 03:50.690 So the spelling mistakes is still okay. 03:50.730 --> 03:56.490 Actually the visibility the AA model has the ability to understand what you mean by reading through 03:56.490 --> 03:57.170 the whole sentence. 03:57.170 --> 03:58.290 So I'm going to press enter. 03:58.330 --> 04:00.610 Let's see what the changes it's going to make okay. 04:00.650 --> 04:04.170 So now it created the input with null name. 04:04.170 --> 04:05.810 But it's still the changes are going on. 04:05.810 --> 04:09.790 Don't think that hey it introduced a compilation issue, so it's still doing it. 04:09.790 --> 04:11.350 So it removed the old function. 04:11.510 --> 04:16.470 And it created a new function for you with the null values over here. 04:16.510 --> 04:16.870 Okay. 04:16.910 --> 04:21.710 And I'm also going to show you there is a change that it made but it's going to error out. 04:21.750 --> 04:23.590 I'll show you what I mean by that. 04:23.630 --> 04:25.150 So let's go ahead and execute this. 04:25.150 --> 04:28.790 So here for the cat the actual value expected is null. 04:28.830 --> 04:31.190 But in our case we have a explicit condition. 04:31.190 --> 04:32.870 Check if the name is null. 04:32.870 --> 04:35.070 We are returning the empty string right. 04:35.070 --> 04:37.510 So I'm going to be providing this over here. 04:37.510 --> 04:43.510 So I'm going to ask it like for the cat instance if the name is null we are returning an empty string. 04:43.510 --> 04:45.150 Please update the test accordingly. 04:45.150 --> 04:46.350 So give it one more shot. 04:46.350 --> 04:51.550 If it's continuously making changes which you don't expect it to do, that means you can jump in and 04:51.550 --> 04:53.470 manually make the change. 04:53.470 --> 04:57.830 So now what it did, was it basically identified, hey, I see the issue over here. 04:57.990 --> 05:00.750 And then it went ahead and made the change for us. 05:00.750 --> 05:04.470 So in the case of Cat, the expected value is going to be empty string. 05:04.470 --> 05:07.550 In the case of dog it's going to be null. 05:07.550 --> 05:09.800 So now let's go ahead and execute the test case. 05:10.040 --> 05:10.400 There you go. 05:10.440 --> 05:11.160 It's all looking good. 05:11.200 --> 05:12.280 I'm going to accept all. 05:12.280 --> 05:12.880 Accept all. 05:12.920 --> 05:13.360 There you go. 05:13.400 --> 05:19.640 So we have successfully created this test case completely written by the AI assistant. 05:19.640 --> 05:22.960 But you see the iterations that we had to go through, right? 05:23.000 --> 05:25.200 This is normally the practice I have seen. 05:25.640 --> 05:33.040 Basically, you need to guide the LLM or the AI assistant to write the code for you in a way that you 05:33.040 --> 05:34.600 expect the output to be. 05:34.600 --> 05:41.800 So in a nutshell, these a assistants are great, but it definitely requires your guidance in writing 05:41.800 --> 05:45.760 the code in the format or the structure or the way you want. 05:45.800 --> 05:49.400 So you basically give a an input, you get an output. 05:49.440 --> 05:54.560 If the output is not aligned to what you want, you give it a guidance on, hey, go ahead and make 05:54.560 --> 05:55.760 the changes accordingly. 05:56.000 --> 05:57.480 Then it will make the change for you. 05:57.480 --> 06:03.280 But overall it's a very good companion that can work with you 24 by seven and can also help you write 06:03.280 --> 06:04.800 the code in a way you want. 06:04.840 --> 06:09.680 So this is how to use the unnamed variables with pattern matching. 06:09.880 --> 06:11.160 This marks the end of this lecture. 06:11.160 --> 06:12.160 Thank you for watching.