WEBVTT 00:00.320 --> 00:00.830 Hi everyone. 00:00.830 --> 00:02.150 Welcome back to this tutorial. 00:02.150 --> 00:07.850 In this tutorial we will code and explore the aggregate functions which are part of the numeric stream. 00:07.850 --> 00:12.430 The aggregate functions are sum, max, min and average. 00:12.440 --> 00:13.970 Let's go ahead and code this one. 00:14.990 --> 00:16.210 Have the interledger open. 00:16.210 --> 00:19.150 I'm going to create a class for this purpose. 00:19.450 --> 00:25.390 Class name is going to be numeric stream aggregate example. 00:26.530 --> 00:30.850 Make this class executable by adding the public static void main method. 00:31.300 --> 00:35.140 And in here, I'm going to use the string. 00:35.140 --> 00:37.750 Before that, let me put this in presentation mode. 00:39.100 --> 00:48.580 I'm going to use in stream dot range closed on comma 50 and I'm going to perform the summation of all 00:48.580 --> 00:50.560 the values in this range. 00:50.770 --> 00:51.610 How do I do it? 00:51.650 --> 00:54.430 So there is a handy method, which is part of the. 00:55.520 --> 00:57.110 Human extreme itself. 00:57.770 --> 00:58.640 We take a look at it. 00:58.640 --> 01:02.120 There is a method called some and some. 01:03.550 --> 01:06.190 Let's print this value and check the result. 01:08.940 --> 01:09.510 Dummies. 01:12.030 --> 01:13.500 And then let's print it. 01:13.860 --> 01:15.330 Go ahead and execute this. 01:16.940 --> 01:17.390 There you go. 01:17.390 --> 01:20.330 It printed the value as 127, five. 01:21.150 --> 01:25.350 Now I want to print the max value of this one. 01:25.980 --> 01:26.550 Right. 01:26.550 --> 01:30.990 So I'm going to again call this one and then call the max value. 01:32.050 --> 01:37.090 There is a method called Max, which is going to return what is a maximum value in this range. 01:37.090 --> 01:38.170 But we know the result. 01:38.170 --> 01:40.240 The answer is going to be 50. 01:40.270 --> 01:41.680 But let's go ahead and check. 01:41.680 --> 01:42.130 What is that? 01:42.130 --> 01:43.030 It is returning. 01:43.150 --> 01:45.520 It is returning something called optional. 01:45.520 --> 01:47.110 And what does it mean? 01:47.110 --> 01:50.350 So if the stream is empty, right. 01:50.350 --> 01:54.520 In that case, it is going to return this optional object with the empty value. 01:54.520 --> 01:55.420 That's what it means. 01:55.420 --> 01:59.320 So we touched on optional a bit in the previous tutorials, but don't worry about it. 01:59.320 --> 02:02.020 We'll be having a separate section for Optional. 02:02.020 --> 02:06.010 We'll discuss all the methods it supports in that particular section. 02:07.770 --> 02:10.440 Know this is going to return something called optional. 02:10.440 --> 02:12.450 INT optional. 02:12.450 --> 02:14.000 INT I'm going to give it a name. 02:14.010 --> 02:14.580 There you go. 02:15.260 --> 02:15.920 So. 02:17.000 --> 02:18.190 We are going to print this one. 02:18.430 --> 02:19.660 Let me print this one. 02:21.050 --> 02:22.460 Then see what it has. 02:24.540 --> 02:26.250 The max value was. 02:28.760 --> 02:30.110 Then give it a colon. 02:30.560 --> 02:31.700 Let's run this. 02:32.480 --> 02:33.080 Run this. 02:33.110 --> 02:35.390 It is giving a max value of 50. 02:35.420 --> 02:36.880 That is what is expected. 02:36.890 --> 02:38.120 But what is our advantage? 02:38.120 --> 02:38.690 Right? 02:38.900 --> 02:41.540 So what is present? 02:42.290 --> 02:42.920 Is present. 02:44.160 --> 02:45.480 And I'm going to run this. 02:46.970 --> 02:49.210 We take a look at it, the value is true. 02:49.220 --> 02:55.400 So the advantage here is that if there is no stream value, if the stream is empty in those kind of 02:55.400 --> 02:59.720 cases, this present is going to be false. 02:59.720 --> 03:08.120 And then you can call if it is present, let's say we can print it like this then optional in dot, 03:08.870 --> 03:12.980 get as int, get as int is a method which will give you the actual int value. 03:13.100 --> 03:15.080 Otherwise the value can be zero. 03:17.030 --> 03:17.720 Run this. 03:19.270 --> 03:19.640 There you go. 03:19.660 --> 03:21.250 It printed the value as false. 03:21.280 --> 03:22.750 If the range is nothing. 03:22.750 --> 03:24.430 So let's write out. 03:27.550 --> 03:35.230 And it's still going to give you some as the value is zero because I believe it creates a range of zero. 03:35.230 --> 03:36.610 Let's go ahead and check that to. 03:38.620 --> 03:39.580 It was a out. 03:41.940 --> 03:42.660 Dot count. 03:44.270 --> 03:46.340 If it prints zero, then it means so. 03:46.340 --> 03:47.570 It printed the value as one. 03:47.570 --> 03:51.380 It still created a range, the value as zero. 03:52.630 --> 03:57.610 So if this dream is empty, then the value will be returned as false. 03:57.610 --> 03:59.740 In the optional event Dot is present. 04:00.010 --> 04:04.540 Let's go ahead and explore the next aggregate function which is the min. 04:04.720 --> 04:10.240 I'm going to use long stream instead of the end stream. 04:10.300 --> 04:12.160 I'm going to use a range closed. 04:12.340 --> 04:20.710 Give the value as one 200 or give the value as 5200 and I'm going to calculate the min value. 04:21.490 --> 04:22.720 We go to this min method. 04:22.720 --> 04:27.790 It is going to return optional long but is something we have to keep in our mind. 04:28.730 --> 04:35.060 So whenever you perform Max and Min operation, it is going to return the optional value. 04:35.090 --> 04:37.820 So it's going to be optional long. 04:41.010 --> 04:43.280 Then give it a name optional long. 04:44.100 --> 04:46.620 I'm going to use the same concept here. 04:48.650 --> 04:57.710 Optional long dot is present, then get the value as get as long and this is going to be zero. 04:58.220 --> 05:03.290 And this the value that I'm expecting the result that it should print would be 50. 05:05.220 --> 05:05.730 There you go. 05:05.730 --> 05:07.620 It printed the value as. 05:08.680 --> 05:10.270 So this is all about the min method. 05:10.300 --> 05:13.270 Let's go ahead and explore the. 05:14.770 --> 05:19.450 Average aggregate function when use in stream again. 05:20.660 --> 05:22.430 Stream dot range closed. 05:22.430 --> 05:25.150 I'm going to give the value as one comma 50. 05:25.380 --> 05:28.790 Then I'm going to perform average. 05:29.300 --> 05:31.080 Go ahead and take a look at the average. 05:31.100 --> 05:34.970 Average is going to return something called optional double. 05:35.750 --> 05:37.880 That is something you have to keep in your mind. 05:38.920 --> 05:39.910 Optional double. 05:40.750 --> 05:42.120 Let's import this. 05:42.160 --> 05:44.410 Want to use the same logic here. 05:46.750 --> 05:52.570 The optional double is present, then I will be get as double. 05:53.480 --> 05:55.730 And then if it is, the stream is empty. 05:55.760 --> 05:58.850 It is going to return the yeast present with the false value. 05:58.880 --> 06:01.490 In that case, we'll print the value as zero. 06:01.940 --> 06:02.810 And this. 06:04.340 --> 06:04.910 There you go. 06:05.060 --> 06:07.670 Enter the value as 25.5. 06:07.700 --> 06:11.720 Basically, that is the average for 1 to 50. 06:13.320 --> 06:20.160 So this is all about the different aggregate functions that int double and the long stream supports. 06:20.610 --> 06:22.620 With this we came to the end of this tutorial. 06:22.650 --> 06:23.700 Thank you for watching.