WEBVTT 00:01.280 --> 00:01.880 Hi everyone. 00:01.880 --> 00:03.230 Welcome back to this tutorial. 00:03.230 --> 00:08.530 In this tutorial we will code and learn about the filter function which is part of the streams. 00:08.540 --> 00:09.320 API. 00:09.440 --> 00:13.670 Filter function is used to filter the elements in the stream. 00:13.670 --> 00:18.470 The input to the filter is a predicate functional interface. 00:18.500 --> 00:22.910 We have seen a lot of examples about filter in the previous tutorials. 00:22.910 --> 00:28.520 If you are pretty confident about filter function, you can skip this tutorial and move on to the next 00:28.520 --> 00:29.090 one. 00:29.120 --> 00:30.950 Let's go ahead and code this one. 00:33.710 --> 00:35.750 So I'm going to expand the strings package. 00:35.750 --> 00:38.420 I'm going to create a class called. 00:39.360 --> 00:41.550 Dreams filter. 00:42.890 --> 00:43.730 Example. 00:45.140 --> 00:51.200 And the next step is I'm going to make this class executable by adding public static, void main method. 00:52.470 --> 00:54.330 Let me put this in presentation mode. 00:57.370 --> 00:57.910 Here we go. 00:58.390 --> 01:04.300 The next step is I'm going to create a method called public static. 01:05.550 --> 01:06.240 List of. 01:07.530 --> 01:08.340 Students. 01:09.830 --> 01:14.510 And then the method name is going to be filter students. 01:15.570 --> 01:16.560 Simple this. 01:18.750 --> 01:19.770 Let's import this one to. 01:20.730 --> 01:22.500 Java dot util package. 01:22.770 --> 01:30.960 The first step is I'm going to call the student database dot, get all students. 01:31.590 --> 01:35.000 So this is going to give you the access to the list of students. 01:35.010 --> 01:38.160 And then I'm going to use the stream method. 01:39.240 --> 01:43.290 The start leveraging or start using the stream functions. 01:44.980 --> 01:46.090 And part of the Streams API. 01:46.420 --> 01:49.060 The next step is I'm going to use the filter. 01:49.450 --> 01:53.140 So if we take a look at here, filter takes in a predicate. 01:53.170 --> 01:54.880 Let's implement the predicate. 01:56.520 --> 02:02.740 So each and every element of the stream is going to be passed to this filter function one by one. 02:02.760 --> 02:10.350 So what I'm going to do, I'm going to apply the filter as, okay, let's say I want only the female 02:10.350 --> 02:13.170 students as part of the whole student database. 02:14.090 --> 02:15.110 Get all students method. 02:15.110 --> 02:16.970 So in that case, how can I do that? 02:17.060 --> 02:26.240 So we can achieve that by calling student dot get gender dot equals. 02:27.170 --> 02:27.620 Female. 02:28.870 --> 02:30.370 What it is going to do. 02:31.960 --> 02:36.410 It is going to the stream function is going to pass the students one by one. 02:36.430 --> 02:44.830 If the student is of gender female, then only it will be passed to the next step in the pipeline. 02:44.860 --> 02:48.730 The next step is I'm going to keep this pipeline really simple. 02:48.850 --> 02:51.940 I'm going to do a collect collect of. 02:53.760 --> 02:54.110 List. 02:55.850 --> 02:57.020 Because that's what we are going to do. 02:57.050 --> 02:58.520 We are going to return. 02:59.700 --> 03:01.080 List of students. 03:04.100 --> 03:05.820 So it's going to return the list of students. 03:05.860 --> 03:09.560 So what this one is going to give you, this one is going to give you. 03:11.620 --> 03:12.970 Stream of students. 03:15.330 --> 03:15.870 Student. 03:16.260 --> 03:23.640 And again, this one is also give you a dream of student But here this will filter out. 03:28.640 --> 03:29.930 Filters and. 03:30.850 --> 03:32.530 Sends only the. 03:33.720 --> 03:38.250 Students whose gender is female. 03:39.590 --> 03:44.820 So whoever has a gender as male will not be passed to the next step. 03:44.840 --> 03:47.870 Basically, they will be filtered out from the stream. 03:49.080 --> 03:50.190 Let's print this. 03:52.830 --> 03:54.390 When adults also served here. 03:56.390 --> 03:57.710 And then I'm going to print this. 03:59.410 --> 04:02.500 To hear all this as soon as you run. 04:02.500 --> 04:07.840 This example is going to print the list of students in the console. 04:09.610 --> 04:09.970 There you go. 04:09.970 --> 04:12.880 It printed all the students in order for more readability. 04:12.910 --> 04:20.590 What I'm going to do, I'm going to print it by iterating all the values dot for each. 04:21.750 --> 04:24.960 Then we are going to use the method reference syntax. 04:25.050 --> 04:25.380 Colon. 04:25.380 --> 04:26.070 Colon. 04:26.070 --> 04:26.620 Println. 04:27.890 --> 04:28.400 There we go. 04:28.730 --> 04:29.180 Run this. 04:29.180 --> 04:31.070 It's going to print all the students in. 04:32.130 --> 04:32.880 Single line. 04:33.150 --> 04:38.700 So if we take a look at it, all the students who ever got printed are female and then it printed in 04:38.700 --> 04:42.660 the order just passed from the screen. 04:43.640 --> 04:45.200 This is all about filter method. 04:45.200 --> 04:49.130 And one more thing if you want, you can add a number of filter here. 04:49.760 --> 04:51.770 So if you want, you can add a filter. 04:52.220 --> 04:54.650 Let's say you want to filter out the student. 04:57.000 --> 05:01.320 Whose grade level is above 3.9. 05:01.320 --> 05:02.880 So you want to do that. 05:02.880 --> 05:05.820 So student dot get GPA. 05:06.960 --> 05:12.240 Now the grade level sorry, it's a GPA is is greater than or equal to 3.9. 05:13.680 --> 05:21.990 So if you do that basically from this list, 3.5 and 3.8, Ginny and Sophia will be filtered out of 05:21.990 --> 05:22.370 the list. 05:22.380 --> 05:25.830 If I run this, it's just going to print Emily. 05:26.070 --> 05:26.760 There you go. 05:27.060 --> 05:33.510 So you can add any number of filter operations here in the pipeline and then you can get your desired 05:33.510 --> 05:35.440 result that you are looking for. 05:35.460 --> 05:37.710 With this, we came to the end of this tutorial. 05:37.740 --> 05:39.000 Thank you for watching.