WEBVTT 00:00.580 --> 00:01.210 Hi everyone. 00:01.210 --> 00:02.560 Welcome back to this tutorial. 00:02.560 --> 00:10.690 In this tutorial we will code and learn about how to perform Min and Max operation on a list of integers. 00:10.960 --> 00:18.640 The first step is I'm going to create a class called PriMS Min Max. 00:19.770 --> 00:20.550 Example. 00:21.550 --> 00:25.690 And then I'm going to make this class executable by adding public static void main. 00:26.200 --> 00:26.980 There you go. 00:27.010 --> 00:29.290 Now I'm going to put this in presentation mode. 00:30.920 --> 00:31.360 Afterwards. 00:31.370 --> 00:33.500 I'm going to build the input list. 00:33.530 --> 00:36.380 List of integers. 00:38.220 --> 00:39.150 And then. 00:41.450 --> 00:43.460 Out of the Java.util package. 00:43.820 --> 00:44.780 Give it a name. 00:45.840 --> 00:47.420 The name is going to be integer list. 00:47.430 --> 00:48.990 You can give any name you want. 00:49.110 --> 00:53.460 Next is arrays dot as list of I'm going to provide the numbers. 00:53.460 --> 00:56.070 Six, seven, eight nine. 00:57.170 --> 00:57.740 And ten. 00:59.690 --> 01:01.970 Okay, so now we have the input list ready. 01:01.970 --> 01:07.340 We want to calculate the max element out of this input list using the reduce function. 01:07.790 --> 01:09.020 Let's create a method. 01:09.620 --> 01:10.730 Public static. 01:11.630 --> 01:17.420 And then this method is going to return an int, which is a maximum number, let's name it as max value 01:18.110 --> 01:22.130 or let's name it as find max value. 01:23.430 --> 01:23.900 Okay. 01:23.910 --> 01:30.060 Now we have we are going to parse the input right this integer list as an input to this method. 01:31.890 --> 01:36.930 The next step is we are going to create integer list, dot stream. 01:37.140 --> 01:41.040 And what we are going to do is we are going to perform the reduce operation. 01:41.160 --> 01:42.360 So reduce operation. 01:42.360 --> 01:44.760 If you take a look at it, there are many variants of it. 01:44.760 --> 01:47.130 But we are going to take a look at this one first. 01:47.160 --> 01:49.800 The reduce operation, which takes. 01:50.920 --> 01:52.000 Go and take a look at that. 01:53.220 --> 01:54.840 For some reason, it is not taking me there. 01:54.870 --> 01:55.110 Okay. 01:55.110 --> 01:55.650 There you go. 01:55.680 --> 01:57.690 The reduce operation takes an. 01:58.610 --> 02:03.110 Identity, which can be a default value or initial value for the first element. 02:03.110 --> 02:05.030 And then next is a binary operator. 02:05.030 --> 02:11.540 We all know binary operator by now, binary operator is a type of function which takes two inputs and 02:11.540 --> 02:13.460 return an output of the same type. 02:14.580 --> 02:16.140 No baserunners. 02:16.230 --> 02:16.980 Zero. 02:17.160 --> 02:19.830 That is going to be the initial value of the stream. 02:19.830 --> 02:21.390 And then it is going to take two inputs. 02:21.390 --> 02:24.930 I'm going to give two different names, X and Y. 02:25.630 --> 02:30.160 And then what we are going to do, our job is to calculate the maximum value. 02:30.190 --> 02:32.080 We all know reduce function by now. 02:32.080 --> 02:37.390 Reduce function always returns a output for every element that it performs. 02:37.390 --> 02:39.060 This reduce operation in the stream. 02:39.070 --> 02:44.890 So if X is greater than Y, then return x. 02:48.330 --> 02:51.270 So for every iteration, for every element. 02:53.750 --> 02:55.540 I'm going to pass this element in this order. 02:55.540 --> 02:56.320 Seven. 02:56.980 --> 02:57.640 Eight. 02:58.920 --> 03:01.140 Nine, then ten. 03:01.350 --> 03:07.050 So for every element it is going to be passed from the stream, it is going to pass these elements one 03:07.050 --> 03:08.490 by one for every element. 03:08.490 --> 03:14.760 It is going to perform this operation and then return the max value and assign the max value to the 03:14.760 --> 03:16.920 Y variable to the x variable. 03:17.400 --> 03:18.450 X variable. 03:20.670 --> 03:23.880 Holds the max value. 03:25.470 --> 03:27.240 For each element. 03:28.410 --> 03:29.370 In the iteration. 03:31.930 --> 03:33.670 Let's talk through this one for the first time. 03:33.670 --> 03:34.480 It is going to pass. 03:34.480 --> 03:40.150 The six is going to be assigned All these values from the stream will be assigned to the Y variable. 03:40.870 --> 03:41.590 Everything. 03:42.520 --> 03:43.120 Why? 03:43.900 --> 03:44.830 Copy this. 03:45.530 --> 03:46.030 Why? 03:46.040 --> 03:46.590 Why? 03:46.590 --> 03:46.890 Why? 03:47.020 --> 03:52.090 So when it when the stream iterates and paths elements one by one, all these values will be assigned 03:52.090 --> 03:58.100 to Y And the result of this iteration result of this function will be assigned to the x variable. 03:58.120 --> 04:03.670 So for the first element, when the six is being passed, x will hold the value zero is zero, greater 04:03.670 --> 04:06.580 than Y is greater, zero greater than six? 04:06.910 --> 04:07.570 Yes. 04:07.570 --> 04:08.830 It's not greater than six. 04:08.830 --> 04:13.910 It's going to return six as the greatest element and that value will be assigned to X. 04:13.930 --> 04:19.510 So when for the next element, seven comes in, x will hold the six, which is a result of the previous 04:19.540 --> 04:23.920 iteration, and then seven is a current value in the stream it compares. 04:23.920 --> 04:25.390 It's a six greater than seven. 04:25.690 --> 04:26.320 No. 04:26.320 --> 04:29.710 Then Y will be returned y, which is seven. 04:29.710 --> 04:34.160 So for the next iteration, seven will be assigned to the X variable. 04:34.180 --> 04:36.430 So that's how the workflow. 04:37.710 --> 04:39.110 Is going to work. 04:39.110 --> 04:44.060 And then the next thing is we are going to call this function and then find out the max value. 04:44.340 --> 04:46.550 INT max value. 04:48.290 --> 04:52.160 Equal to find max value and then pass this integer list. 04:53.280 --> 04:56.880 Okay, now I'm going to print this max value. 05:00.370 --> 05:01.490 Max values. 05:02.550 --> 05:05.280 And then I'm going to create. 05:07.360 --> 05:07.990 Render result. 05:08.380 --> 05:09.610 Let's run this and then check. 05:11.230 --> 05:14.560 There is an issue because I did not return this. 05:14.590 --> 05:16.030 You have to return this. 05:16.780 --> 05:18.400 Let's run this and check the result. 05:20.770 --> 05:22.360 So it printed the value as ten. 05:22.390 --> 05:25.120 That is what is expected for the max value. 05:25.210 --> 05:30.190 Right now, what we will do is let's pass an empty list and then see what happens. 05:30.220 --> 05:31.540 I'm going to comment this one. 05:33.770 --> 05:37.610 And then I'm going to give it a name called New List. 05:39.870 --> 05:40.600 And pass this. 05:40.620 --> 05:43.080 Let's see, what is a value that it is going to return. 05:44.910 --> 05:50.340 Basically we are not passing any value, but still the max value is returned as zero. 05:50.610 --> 05:51.780 That is not right. 05:51.780 --> 05:55.020 The reason being if the input value is. 05:55.050 --> 06:00.810 If the input list is empty, ideally it should return us an empty value, not zero because zero. 06:00.840 --> 06:06.840 The reason why it is returning zero is because we have a default value set and this is not correct. 06:06.840 --> 06:09.450 So there is an another approach for that. 06:09.450 --> 06:10.800 So you should always. 06:11.370 --> 06:18.900 You should avoid assigning a default value whenever you are performing a min and max value from a stream 06:18.930 --> 06:20.160 of integers. 06:20.190 --> 06:23.040 That is something which we have to keep it in our mind. 06:23.190 --> 06:26.190 So I'm going to create another method. 06:27.910 --> 06:31.720 And then I'm going to name this one as point value optional. 06:31.720 --> 06:34.570 So we talked about optional a bit in the previous tutorial. 06:34.600 --> 06:37.330 Now we will know the benefit of using Optionals. 06:37.480 --> 06:42.580 So in here what we are going to do, I'm going to remove this default value. 06:42.610 --> 06:44.530 Let's see, we have a compilation issue here. 06:44.530 --> 06:46.930 Let's take a look at what is that issue? 06:47.260 --> 06:51.790 Make find Max value optional return Java.util dot optional. 06:51.790 --> 06:55.380 Right now we are returning the integer, so this one is trying to return an integer. 06:55.390 --> 07:00.160 They're asking us to change the return type to optional of integer. 07:00.160 --> 07:01.360 Let's go ahead and do that. 07:02.770 --> 07:04.410 Click on this, it's going to change the type. 07:04.420 --> 07:05.200 So there you go. 07:05.230 --> 07:06.490 It written this. 07:06.580 --> 07:12.400 Now what we are going to do, I'm going to come on this one out and then. 07:13.340 --> 07:14.150 Import this. 07:17.710 --> 07:22.330 I'm gonna call this method, find Max value optional. 07:22.330 --> 07:24.190 I'm going to pass this integer list. 07:24.790 --> 07:28.360 So this is going to return me an optional of type integer. 07:30.000 --> 07:33.330 And then this is going to be max value. 07:35.190 --> 07:35.940 Optional. 07:38.520 --> 07:39.240 Equal to this. 07:40.020 --> 07:43.110 Now, how can we get the result? 07:43.380 --> 07:46.890 The way to get it is if the max value has a value. 07:47.730 --> 07:52.920 Then the use present method call is going to return as a boolean as true. 07:52.950 --> 07:53.640 Right? 07:55.170 --> 07:56.010 If it is true. 07:56.040 --> 07:58.170 Meaning there is some value present in that one. 07:59.100 --> 08:00.990 Gonna print the value. 08:02.180 --> 08:04.340 Max value using optional. 08:05.400 --> 08:08.190 This max value optional. 08:10.030 --> 08:14.950 Dot get get will give you the actual value in that particular optional object. 08:15.340 --> 08:21.190 And if it is, if there is no value present in those cases, we can give. 08:23.180 --> 08:23.540 In print. 08:23.540 --> 08:25.310 The output has no max value. 08:27.460 --> 08:30.190 Okay, now let's run this example and then check. 08:34.430 --> 08:37.560 If you take a look at the result, both the result are the same. 08:37.580 --> 08:43.580 The things will be they're going to be interesting when we pass the list as empty value. 08:43.880 --> 08:46.460 If we pass the list as empty value, what will happen? 08:47.300 --> 08:52.640 So ideally I'm expecting no max value found because the input is empty. 08:52.670 --> 08:53.960 Or you can have. 08:56.640 --> 09:03.450 Input list is empty because this is the right message, because we passed an empty list and we want 09:03.450 --> 09:04.110 to print. 09:04.140 --> 09:04.500 Okay. 09:04.500 --> 09:10.980 I do not see any input value, so I'm not going to send the optional object with some value. 09:11.010 --> 09:13.410 It is going to send an empty optional. 09:13.410 --> 09:16.560 We can print this optional and then check to this out. 09:18.830 --> 09:20.240 Optional Max's. 09:22.490 --> 09:23.060 Okay. 09:23.240 --> 09:24.140 Run this check. 09:26.690 --> 09:27.650 If you run it. 09:27.800 --> 09:28.370 There you go. 09:28.550 --> 09:32.690 So it printed the optional max is optional dot empty. 09:33.230 --> 09:35.840 And then the input list is empty is what we printed. 09:36.290 --> 09:38.300 Let's say we. 09:40.600 --> 09:41.470 Is this what will happen? 09:43.710 --> 09:46.610 Going to print optional with a value ten. 09:46.620 --> 09:55.110 So this is one of the key difference of using optional and without optional while calculating the max 09:55.110 --> 09:55.730 value. 09:55.740 --> 10:03.000 So always keep in your mind if you are calculating a max value, it is always recommended to use optional 10:03.360 --> 10:04.500 as a return type. 10:06.470 --> 10:10.210 We will discuss about the min operation in the next tutorial. 10:10.220 --> 10:12.400 With this we came to the end of this tutorial. 10:12.410 --> 10:13.300 Thank you for watching.