WEBVTT 00:00.900 --> 00:01.470 Hi everyone. 00:01.470 --> 00:02.830 Welcome back to this tutorial. 00:02.850 --> 00:05.820 In this tutorial we'll talk about method reference. 00:06.750 --> 00:10.320 We will be discussing the theory part as part of this tutorial. 00:11.390 --> 00:14.480 This concept got introduced as part of Java eight. 00:14.690 --> 00:21.560 The sole purpose of method reference is to simplify the implementation of functional interfaces. 00:21.710 --> 00:25.370 You might be wondering, we already did that by using lambdas. 00:25.400 --> 00:30.140 Lambdas helped us to move away from creating anonymous inner classes. 00:30.200 --> 00:36.470 Yes, you are right, but this one is going to simplify the lambda expression itself. 00:37.600 --> 00:43.450 And also call method reference as a shortcut for the lambda expressions from the name itself. 00:43.460 --> 00:47.780 It is clear that this one is used to refer a method in a class. 00:47.800 --> 00:50.650 Let's take a look at the syntax of the method reference. 00:51.580 --> 00:52.930 The syntax is class. 00:52.930 --> 00:56.470 Name a double colon operator followed by the method name. 00:56.500 --> 01:01.900 The right hand side references to the method name and the left hand side references to the class name. 01:02.580 --> 01:06.090 Let's talk about the different options that are presented here. 01:06.120 --> 01:10.230 First example is a class name followed by the instance method name. 01:10.260 --> 01:15.000 The second example is a class name, followed by the static method name in that class. 01:15.180 --> 01:20.040 And then the third example is an instance of the class, followed by the method name. 01:20.070 --> 01:25.110 Let's take a look at some of the examples where the method reference is applicable. 01:26.060 --> 01:32.450 Metal reference can be used wherever the lambda expression is referring to the method directly. 01:33.900 --> 01:35.550 Let's take a look at one of the example. 01:35.550 --> 01:39.450 This is one of the example which we coded in our prior tutorials. 01:39.480 --> 01:45.930 Here what happens is we are taking an input as a string and then we are applying the to uppercase on 01:45.930 --> 01:46.500 top of it. 01:46.860 --> 01:49.990 Basically, this is a function functional interface implementation. 01:50.010 --> 01:52.470 The input is a string and output is a string. 01:52.500 --> 01:55.710 How can we rewrite this using the method reference? 01:56.070 --> 01:58.560 Take a look at the method reference implementation. 01:58.740 --> 02:01.590 We give the class name as if you remember the syntax. 02:01.590 --> 02:04.470 The syntax is class name double colon operator. 02:04.470 --> 02:06.760 Followed by that we provide the method name. 02:06.780 --> 02:12.390 So the syntax is going to be the string, which is a class name and followed by the double colon and 02:12.390 --> 02:17.100 then the two uppercase method, because that's what we are trying to achieve as part of this lambda 02:17.100 --> 02:17.850 expression. 02:18.770 --> 02:24.020 So using method reference, we can write simpler and more readable code. 02:24.940 --> 02:29.620 Let's take a look at some of the examples where the method reference is not applicable. 02:31.120 --> 02:32.590 Take a look at an example. 02:32.800 --> 02:34.690 We take a look at this example here. 02:34.690 --> 02:36.460 We wrote our own logic. 02:36.610 --> 02:42.660 We are not referencing to any method that is implementing this predicate functional interface. 02:42.670 --> 02:49.060 In these kind of use cases, it is difficult to write a method reference for this one, but there is 02:49.060 --> 02:55.270 a workaround in solving these kind of problems and writing a method reference for these kind of codes 02:55.270 --> 02:55.690 too. 02:55.780 --> 03:01.630 We will get into those kind of examples and we will implement those in our next tutorial. 03:01.810 --> 03:04.980 But now this is all about method reference. 03:04.990 --> 03:07.310 With this we came to the end of this tutorial. 03:07.330 --> 03:08.410 Thank you for watching.