WEBVTT 00:00.470 --> 00:00.980 Hi everyone. 00:00.980 --> 00:02.270 Welcome back to this tutorial. 00:02.270 --> 00:06.080 In this tutorial we will code and explore the mapping Collector. 00:06.880 --> 00:14.120 Mapping collector applies a transformation function first and then collects the data in a collection. 00:14.140 --> 00:15.850 The collection could be of any type. 00:15.850 --> 00:17.440 It could be a list set. 00:17.470 --> 00:20.110 Let's go ahead and explore this using an example. 00:20.770 --> 00:23.230 I've then open here what I'm going to do. 00:23.260 --> 00:24.820 I'm going to create a. 00:25.750 --> 00:29.470 A class called frames Mapping. 00:29.800 --> 00:30.700 Example. 00:32.430 --> 00:37.530 And then I'm going to make this class executable by adding public static void main. 00:39.580 --> 00:41.110 We put this in presentation mode. 00:44.120 --> 00:44.930 What I'm going to do. 00:44.930 --> 00:51.440 I'm going to call the student database class dot, get all students, and then call the stream method. 00:52.250 --> 00:55.130 Followed by that we are going to call the collect method. 00:55.160 --> 00:58.100 In here we are going to call the mapping method. 00:59.550 --> 01:00.000 Right. 01:00.540 --> 01:01.650 Import this. 01:02.860 --> 01:04.630 Have the static import option available. 01:04.630 --> 01:05.950 I'm going to select that option. 01:06.310 --> 01:09.010 If you take a look at it, mapping takes two input. 01:09.040 --> 01:14.830 One is the function, which is a mapper, and another one is a downstream, which represents what is 01:14.830 --> 01:18.100 a type of collection which you want the result to be collected. 01:19.360 --> 01:22.180 So I just want the student names. 01:22.720 --> 01:23.560 Student. 01:24.730 --> 01:25.510 This is a function. 01:25.510 --> 01:25.870 Colon. 01:25.870 --> 01:26.470 Colon. 01:29.010 --> 01:30.090 Import the student. 01:31.510 --> 01:33.160 Put class Colon. 01:33.160 --> 01:33.660 Colon. 01:33.670 --> 01:34.690 Get name. 01:35.470 --> 01:38.200 Followed by that you're going to do to. 01:41.760 --> 01:43.660 Wait for this. 01:43.740 --> 01:44.160 There you go. 01:44.310 --> 01:48.570 And then this is going to collect the list of students. 01:50.220 --> 01:52.530 Names which are of type string. 01:54.170 --> 01:54.860 Names list. 01:56.370 --> 01:58.860 We go import this? 01:59.430 --> 02:01.200 What are the java.util package? 02:01.620 --> 02:02.850 Let's print this one. 02:04.260 --> 02:05.640 Names list. 02:10.090 --> 02:10.820 Does this one. 02:10.840 --> 02:13.300 Let's go ahead and run this and check the result. 02:16.750 --> 02:19.180 We printed all the names in the list. 02:19.210 --> 02:20.110 Now. 02:21.570 --> 02:24.600 I'm going to do the same kind of operation I'm going to collect. 02:24.600 --> 02:30.270 I'm going to use the name to be mapped, but I want to collect the result in a set. 02:34.710 --> 02:38.920 Pass to set is going to be set of strings. 02:38.940 --> 02:40.470 Let's import this. 02:40.500 --> 02:44.220 This is going to be I'm going to give it a new name called Names Set. 02:44.920 --> 02:46.170 I'll copy this out. 02:46.560 --> 02:47.560 Put it here. 02:47.580 --> 02:48.990 Let's import this to set to. 02:49.020 --> 02:53.280 This is going to be a static import here like the way we did for to list. 02:54.630 --> 02:56.370 And here I'm going to print the names. 02:58.940 --> 03:00.800 Run this and check the result. 03:02.410 --> 03:02.890 Result. 03:03.520 --> 03:07.090 We printed the it collected the names in a set. 03:07.120 --> 03:10.120 If you remember this, in the past we used to do. 03:11.380 --> 03:14.980 Me for this one without. 03:16.250 --> 03:17.870 The mapping method in the past. 03:17.870 --> 03:24.380 If we just want the names, what we do is we call the map method and then student Colon, Colon, get 03:24.410 --> 03:27.200 name, and then we use the collect. 03:27.800 --> 03:29.000 We give it as to list. 03:30.640 --> 03:33.640 So with this we can avoid one additional. 03:33.640 --> 03:39.760 With this mapping method, we can avoid that additional intermediate operation and then we can perform 03:39.760 --> 03:42.130 everything using the mapping method. 03:43.330 --> 03:45.380 So this is all about mapping method. 03:45.400 --> 03:47.560 With this, we came to the end of this tutorial. 03:47.590 --> 03:48.640 Thank you for watching.