WEBVTT 00:00.320 --> 00:00.830 Hi everyone. 00:00.830 --> 00:02.060 Welcome back to this tutorial. 00:02.060 --> 00:09.050 In this tutorial we will code and explore the three argument version of grouping by So in the previous 00:09.050 --> 00:14.210 two tutorials we explored the one argument version and the two argument version. 00:14.210 --> 00:14.750 Right. 00:14.750 --> 00:17.150 Let's go ahead and explore the three argument version. 00:17.150 --> 00:21.740 Before I do that, I would like to explore what is happening with the two argument version. 00:21.770 --> 00:27.530 If we go and take a look at the two argument version, here we are passing the classifier and downstream. 00:27.530 --> 00:33.440 But internally what this does is it passes the third argument here. 00:33.440 --> 00:39.590 So the classifier is passed as a first argument and the HashMap knew this is a supplier which they are 00:39.590 --> 00:40.190 passing. 00:40.190 --> 00:48.350 So the output is always going to be HashMap because here they are performing this internally. 00:48.380 --> 00:54.290 So what we are going to do is we are going to override this and then pass the supplier from our end. 00:54.320 --> 00:59.750 That's what we are going to do as part of the three argument version of grouping by. 01:03.810 --> 01:06.960 That's going to be public static. 01:07.780 --> 01:08.380 Wide. 01:10.080 --> 01:11.640 Three argument. 01:13.530 --> 01:14.310 Group by. 01:15.970 --> 01:17.680 And in here it accepts. 01:17.680 --> 01:24.040 It accepts student database dot get all students dot stream. 01:24.160 --> 01:27.220 And then we're going to call the collect method. 01:27.220 --> 01:33.550 In the collect method, we're going to perform the group by of name. 01:33.550 --> 01:35.110 I'm going to copy this from here. 01:35.110 --> 01:40.380 That is the first argument, which is a classifier and followed by that what are we going to do? 01:40.390 --> 01:46.270 We are going to use the linked hash map, colon, colon, new, that is a supplier. 01:46.270 --> 01:52.330 And the third one is going to be we are going to use the another collector, which is going to be to 01:52.360 --> 01:53.980 set because we have seen. 01:56.530 --> 02:02.590 We have seen lists throughout all these examples, but here we are going to override that and then use 02:02.590 --> 02:04.870 to set as a collector. 02:04.870 --> 02:06.850 So what is the output? 02:06.850 --> 02:11.080 It is going to be linked hash map and the key, what is a key? 02:11.080 --> 02:14.770 The key is going to be the name. 02:15.920 --> 02:17.540 It is of type string. 02:17.540 --> 02:22.820 And then this is going to be set of student. 02:24.890 --> 02:26.200 So let's give it a name. 02:26.210 --> 02:27.890 Let's import the set here. 02:29.550 --> 02:33.720 The name is going to be student. 02:35.330 --> 02:36.800 Linked hash map. 02:39.050 --> 02:39.260 Good. 02:40.040 --> 02:40.610 There you go. 02:40.810 --> 02:42.110 Then I'm going to print this. 02:45.310 --> 02:47.330 And let's revisit this again. 02:47.350 --> 02:49.540 The first one determines the key here. 02:49.540 --> 02:52.510 The second parameter determines the output. 02:52.540 --> 02:57.790 What kind of output it is, what kind of connection it is going to return. 02:57.790 --> 03:05.170 And this two set determines what is a value for the output that it is going to generate. 03:05.500 --> 03:09.520 Let's run this example and then validate the result. 03:11.280 --> 03:12.270 Let's run this. 03:12.640 --> 03:16.380 Going to have a name and their student as a. 03:17.870 --> 03:18.440 Value. 03:18.440 --> 03:21.590 So Adam and the whole student object mapped out. 03:21.740 --> 03:23.540 Jenny And the whole student. 03:23.570 --> 03:24.650 Object mapped to it. 03:25.190 --> 03:30.200 So this is all about the three argument version of grouping by. 03:30.230 --> 03:32.340 But this we came to the end of this tutorial. 03:32.360 --> 03:33.590 Thank you for watching.