WEBVTT 00:00.080 --> 00:00.680 Hi everyone. 00:00.680 --> 00:01.250 Welcome back. 00:01.250 --> 00:05.810 In this lecture we will code and learn about the new enhanced switch in Java. 00:05.840 --> 00:08.390 I'll start with some theory first as like the other lectures. 00:08.390 --> 00:10.520 And then we'll get to the coding part. 00:10.640 --> 00:13.640 Switch statements have been part of the language since the beginning. 00:13.640 --> 00:19.340 Enhanced switch is an enhancement to the existing switch statement, which got released as part of Java 00:19.340 --> 00:19.820 14. 00:19.850 --> 00:24.860 The new enhanced switch is an expression which means it returns a value. 00:24.860 --> 00:30.080 Basically, it's not a switch statement anymore, it is an expression. 00:30.080 --> 00:32.660 Let me explain this using a simple example. 00:32.660 --> 00:37.250 Here is a function that returns a number of days based on the month and year. 00:37.280 --> 00:39.710 Now let's quickly look into the implementation. 00:39.710 --> 00:45.230 Since this function returns a value, you need to define an integer, because the return type of this 00:45.230 --> 00:51.320 particular function is an integer, and then we default that value to be zero, and then we have a switch 00:51.320 --> 00:55.430 statement for all the months that fall under 30 days bucket. 00:55.430 --> 00:58.790 And then we update the number of days variable to 30. 00:58.820 --> 01:05.680 If the passed in month to the function is April, June, September or November and then we break the 01:05.680 --> 01:10.000 case statement, and then we return the number of days in the case of February. 01:10.030 --> 01:12.040 We have a specific case statement for that. 01:12.040 --> 01:17.740 And then we have the default block for the rest of the months, which have the number of days as 31. 01:17.740 --> 01:23.200 And then we have the default block for the rest of the months, which has the number of days as 31. 01:23.200 --> 01:26.980 So this is an old way of implementing a switch statement. 01:26.980 --> 01:32.530 This one works really well, and most of you might have done a similar kind of implementation in your 01:32.530 --> 01:33.220 experience. 01:33.250 --> 01:37.330 Now let's look at the same implementation using the enhanced switch. 01:37.360 --> 01:42.970 The first thing that comes into my mind when I look at this implementation is that it looks very concise 01:42.970 --> 01:45.250 and looks much cleaner to me. 01:45.250 --> 01:51.550 So now let's dive into the implementation and understand what this implementation mean and how it works. 01:51.550 --> 01:55.030 The key thing to notice here is that switch is an expression. 01:55.030 --> 01:59.470 So we place the return keyword on the switch expression itself. 01:59.470 --> 02:05.050 And the next thing is that we have multiple case labels allowed in the enhanced switch. 02:05.050 --> 02:11.910 So in this case we have September April June and November have the same case label, and number three 02:11.910 --> 02:16.320 is that the brake statement is replaced by the arrow on the value. 02:16.350 --> 02:17.790 The switch is going to return. 02:17.790 --> 02:21.270 So basically we don't have to deal with the brake statement anymore. 02:21.270 --> 02:24.000 And the same is applicable for the following case statement. 02:24.000 --> 02:29.640 And then we have a default block that takes care of handling the scenario where it needs to handle the 02:29.640 --> 02:30.930 remaining conditions. 02:30.930 --> 02:37.830 This makes the enhanced switch looks elegant, and it is also can be used in advanced use cases like 02:37.830 --> 02:41.040 pattern matching, which I'll cover in the future part of the course. 02:41.040 --> 02:45.270 I hope you have a good understanding of how to implement the enhanced switch. 02:45.300 --> 02:48.090 Now it's time to explore the enhanced switch in action. 02:48.090 --> 02:51.600 For that, we are going to switch back to IntelliJ and then start exploring it. 02:51.600 --> 02:53.160 So I'm back in IntelliJ here. 02:53.160 --> 02:53.670 And in here. 02:53.670 --> 02:54.720 What we are going to do. 02:54.750 --> 02:57.630 We are going to be opening the enhanced switch package. 02:57.630 --> 03:02.430 So in the enhanced switch package you will have the implementation already present over here. 03:02.430 --> 03:06.390 And this is a older way of implementing the switch statement okay. 03:06.420 --> 03:11.940 And if you take a look at the input to this function month is an enum which represents all the months. 03:11.940 --> 03:17.250 It is part of the Java.time package itself, and then the year is something which is being passed. 03:17.250 --> 03:20.700 So based on the year, we are going to use the leap year function. 03:20.700 --> 03:22.260 That's part of the year class. 03:22.260 --> 03:24.840 This is also part of the Java.time package, I believe. 03:24.870 --> 03:29.130 There you go to determine whether the current year is a leap year or not. 03:29.130 --> 03:34.620 Because if it's a leap year, we need to return the value of the number of days to be 29. 03:34.650 --> 03:37.410 Otherwise, we need to return the value as 28. 03:37.410 --> 03:40.410 For rest of the condition, we are returning the value as 30. 03:40.440 --> 03:42.420 So there is a test case already available. 03:42.420 --> 03:43.950 Let's go ahead and take a look at that one. 03:45.000 --> 03:47.010 So there is a days and month test. 03:47.040 --> 03:48.870 Let me put this in side by side view. 03:48.900 --> 03:53.550 So this one actually if you take a look at it it uses something called parameterized test. 03:53.550 --> 03:58.410 If you are hearing this term for the very first time, it is very simple and easy to upskill yourself 03:58.410 --> 03:58.950 on this one. 03:58.950 --> 04:03.660 So you can think of this as a test where the function parameters are. 04:03.660 --> 04:06.930 The input parameters are returned from a different function. 04:06.930 --> 04:08.760 So in this case I'm using the method source. 04:08.760 --> 04:10.740 And then the function name is input. 04:10.740 --> 04:13.860 So as soon as I highlight this one the reference goes here. 04:13.860 --> 04:20.270 So what this does is that here we are passing the arguments as February September, and we are passing 04:20.270 --> 04:23.750 the expected number of days to be returned as part of this call. 04:23.750 --> 04:29.630 So these two values, the month and expected number of days, is being returned by this function as 04:29.660 --> 04:30.920 a stream of arguments. 04:30.920 --> 04:36.290 So when we execute this function, it is going to be getting executed three times because that's what 04:36.290 --> 04:37.490 this input function returns. 04:37.490 --> 04:39.740 It returns a stream of three arguments. 04:39.740 --> 04:43.760 The first argument is February and the expected number of days is 28. 04:43.760 --> 04:47.750 And the second argument is September and the expected number of days is 30. 04:47.780 --> 04:53.120 And the third argument is January, and the expected number of days is going to be 31. 04:53.120 --> 04:56.750 Let's execute this test case and then look into the results over here. 04:57.800 --> 04:58.160 There you go. 04:58.160 --> 04:58.400 You see. 04:58.430 --> 04:58.730 Right. 04:58.730 --> 05:00.920 All these three conditions are executed. 05:00.920 --> 05:06.920 And the three conditions basically the input to the test cases is passed by this input function. 05:06.920 --> 05:12.590 So now what we are going to do is we are going to be implementing the same functionality using the enhanced 05:12.590 --> 05:13.010 switch. 05:13.010 --> 05:15.830 So what we are going to do we are going to create another function. 05:15.830 --> 05:19.520 So that's going to accept something similar okay. 05:19.520 --> 05:22.570 But I'm going to name this function as get days this v2. 05:24.940 --> 05:25.330 Okay. 05:25.360 --> 05:30.010 And in here, what we are going to do, we are going to use the enhanced switch. 05:30.010 --> 05:32.380 So enhanced switch is an expression right. 05:32.380 --> 05:35.380 So in this case let's do a return and then pass the switch. 05:35.380 --> 05:38.050 And then you pass a month over here okay. 05:38.080 --> 05:41.290 And then what we are going to do let's implement the first condition. 05:41.290 --> 05:45.340 The first condition is a case for all these different months. 05:45.340 --> 05:47.350 And the return value is going to be 30. 05:47.380 --> 05:47.950 Right. 05:47.950 --> 05:53.740 So what we can do we can do a case and then you can add September. 05:55.780 --> 05:57.280 April June and November. 05:57.310 --> 05:57.850 Right. 05:57.850 --> 06:03.190 So it can be April June and November. 06:03.190 --> 06:06.070 And the value that we want to return is 30 days. 06:06.100 --> 06:08.920 That's what we want to do right for February. 06:08.950 --> 06:12.340 So in this case it's going to be February case February. 06:12.340 --> 06:17.410 And if the year is a leap year then we need to return the value as 29. 06:17.410 --> 06:21.790 If the year is not a leap year, then we need to return the value as 28. 06:21.820 --> 06:26.290 I am recording this lecture where the year is 2023, which is not a leap year. 06:26.290 --> 06:28.770 So in this case I'm going to have a check year. 06:28.770 --> 06:31.950 Dot is leap year and then pass this value. 06:31.980 --> 06:33.930 So in this case pass the year over here. 06:33.930 --> 06:37.770 And if the year is leap year it's going to return the boolean as true. 06:37.770 --> 06:40.710 So we will have the number of days as 29. 06:40.740 --> 06:43.260 Otherwise the value is going to be 28. 06:43.350 --> 06:46.530 Okay I believe here we need to add the semicolon. 06:46.530 --> 06:48.390 And the next one is the default case. 06:48.390 --> 06:52.050 So default case we want to return the value as 31 okay. 06:52.080 --> 06:57.000 So we have our very first enhanced switch statement implemented. 06:57.000 --> 07:01.230 And if you take a look at the number of lines just for the sake of comparing the number of lines, the 07:01.230 --> 07:04.890 number of lines is just three lines for the same implementation. 07:04.890 --> 07:10.710 And we don't have to define this redundant variable and then mutate that value in order to determine 07:10.710 --> 07:11.640 the result. 07:11.640 --> 07:15.990 So in here we basically have the return value represented in the lambda. 07:15.990 --> 07:19.260 So what we will do how do we make sure the functionality works as expected. 07:19.260 --> 07:21.810 So now we are going to write a similar test. 07:21.840 --> 07:24.090 We'll leverage the same code. 07:24.090 --> 07:27.720 But in this case the function name is going to be get this v2. 07:27.720 --> 07:32.970 And we are going to be invoking the function name as get is this v2 and the method input source is still 07:32.970 --> 07:37.470 going to be the same as long as this test case succeeds without any issue. 07:37.500 --> 07:40.020 Our implementation works as expected. 07:40.020 --> 07:42.480 So in this case, let's go ahead and execute this test case. 07:43.170 --> 07:43.620 There you go. 07:43.650 --> 07:46.170 Our execution of the test case is all green. 07:46.200 --> 07:52.770 That means our enhanced switch works very similar to the older implementation of the same functionality. 07:52.800 --> 07:55.860 Now let's go ahead and execute this whole test. 07:55.860 --> 08:00.330 So this is going to execute both the get days and get days v2 function. 08:00.330 --> 08:05.280 And we have implemented our very first enhanced switch in our modern Java. 08:05.310 --> 08:11.280 Some of the quick things to recollect is that in modern Java, with the usage of enhanced switch return 08:11.280 --> 08:15.690 keyword placed on the switch statement, the reason being switch is an expression. 08:15.690 --> 08:21.630 You can basically return the whole switch and the condition gets evaluated and the appropriate value 08:21.660 --> 08:23.730 that's after the lambda gets returned. 08:23.760 --> 08:27.180 I hope you all have a good understanding about how enhanced switch works. 08:27.180 --> 08:32.130 There are a couple of advanced topics let's try to enhance switch, which I'll be covering in the following 08:32.160 --> 08:32.760 lectures. 08:32.760 --> 08:34.080 This marks the end of this lecture. 08:34.080 --> 08:35.100 Thank you for watching.