1 00:00:01,100 --> 00:00:07,190 All right, so in the next couple of videos, we are going to use a bunch of lambda expressions, and 2 00:00:07,190 --> 00:00:11,870 in general, it's a good idea for you to understand Lumba expressions in more depth because we have 3 00:00:11,870 --> 00:00:14,490 covered them, but really just a tiny bit. 4 00:00:14,690 --> 00:00:19,070 And now we're going to see the different aspects of lambda expressions and how they are used and the 5 00:00:19,070 --> 00:00:20,580 advantages and so forth. 6 00:00:20,600 --> 00:00:25,190 So I'm going to go over that in this presentation, but then we're going to use it extensively in the 7 00:00:25,550 --> 00:00:30,470 room database demo as well as in the rest of the course, basically. 8 00:00:30,950 --> 00:00:33,950 So let's look at CoQ10 lambdas. 9 00:00:34,520 --> 00:00:41,270 So lenders are popular in different programming language, and they are well known for, for example, 10 00:00:41,300 --> 00:00:44,870 being simple and concise way to create functions. 11 00:00:45,890 --> 00:00:53,240 Then they are also known as functions with no name because you can just add implementations within its 12 00:00:53,240 --> 00:00:58,580 block, and then they are also used to parse functions as parameters to other functions. 13 00:00:59,180 --> 00:01:00,110 So let's look at this. 14 00:01:00,740 --> 00:01:04,550 So there are various ways to create a lambda function, depending on the requirements. 15 00:01:04,879 --> 00:01:07,220 One is as a parameter, for example. 16 00:01:07,460 --> 00:01:14,000 So you see, we have first the variable name, then a column with the parentheses for the parameter 17 00:01:14,210 --> 00:01:17,240 and then an arrow with a return type. 18 00:01:17,930 --> 00:01:27,440 And here's an example with some as the variable in the integer parameter named result and a unit return 19 00:01:27,440 --> 00:01:30,530 type, which means it's going to return nothing. 20 00:01:31,010 --> 00:01:34,340 So this is like a void function that you would see in Java, for example. 21 00:01:35,030 --> 00:01:43,190 So in this example here, the arithmetic class has a lambda declared in its constructor with an integer 22 00:01:43,190 --> 00:01:45,470 parameter and a Boolean return type. 23 00:01:45,890 --> 00:01:52,310 And then in the end, its block of the class we pass a value five once the class is initialized. 24 00:01:52,880 --> 00:01:58,340 So we see this is again using a lambda and this time as a parameter. 25 00:01:58,370 --> 00:02:03,530 So you can basically use one does at all different kinds of points of your application. 26 00:02:04,160 --> 00:02:10,310 So another way can be to call a number within a block using the Invoke operator. 27 00:02:10,699 --> 00:02:18,200 So here in this way, we call the method when the button is clicked and you can receive this value at 28 00:02:18,200 --> 00:02:21,560 the point of initializing the arithmetic class. 29 00:02:22,100 --> 00:02:28,790 So we are invoking or calling the same function right here with the value of five, so we're passing 30 00:02:28,790 --> 00:02:29,630 five to it. 31 00:02:30,500 --> 00:02:32,990 So it's here, this some. 32 00:02:34,690 --> 00:02:41,980 OK, now to actually parse an argument or implementation of the lambda, we use curly braces. 33 00:02:42,400 --> 00:02:48,310 So in this arithmetic class will receive the result passed in the init block and then check if the value 34 00:02:48,310 --> 00:02:51,910 is greater than five because it has a Boolean return type. 35 00:02:52,120 --> 00:02:56,830 We have a true or false at the end of each condition block here as well. 36 00:02:58,570 --> 00:03:04,120 So we can also create a method first and then call it with the lumber. 37 00:03:04,840 --> 00:03:11,950 So you see we have this method operation at the top and then we call it using a lambda at the bottom. 38 00:03:12,550 --> 00:03:14,980 OK, so this was all rather theoretical. 39 00:03:15,460 --> 00:03:21,670 Now let's go ahead and see how we can use lambdas in real world examples, in particular in our room 40 00:03:21,670 --> 00:03:22,960 database example.