1 00:00:00,210 --> 00:00:05,670 Hey friends I'm very happy and excited to start the journey so let's get you onboard. 2 00:00:05,700 --> 00:00:07,440 So what are our generics 3 00:00:11,720 --> 00:00:18,500 simply stating genetics are mechanism for type checking at compile time 4 00:00:26,520 --> 00:00:28,930 and genetics but introduced in Java 5. 5 00:00:29,100 --> 00:00:36,740 And why should we use a genetics in application that may get any combines them at a run right in the 6 00:00:36,750 --> 00:00:37,240 court. 7 00:00:37,260 --> 00:00:43,430 Or we may encounter exception of trunk time line when we get any compile them enter the compiler forces 8 00:00:43,440 --> 00:00:44,640 us to fix that error. 9 00:00:45,060 --> 00:00:52,290 But in case of runtime enter the compiler it says does not know that there is going to be any error 10 00:00:52,290 --> 00:01:00,300 in that code and it is difficult for us to find that event actually that we're getting that exception. 11 00:01:00,540 --> 00:01:06,390 And we have to debug the code to find out that there or at which line we're getting the exception. 12 00:01:06,390 --> 00:01:10,830 So it becomes very difficult to find out very how we are getting the exception. 13 00:01:11,100 --> 00:01:19,690 So by using genetics we can a whites situation in Greece all type by using genetics with Dan the compiler 14 00:01:19,690 --> 00:01:26,130 that this is the data type I'm going to use and if I do any mistake then raise a compile time matter. 15 00:01:26,170 --> 00:01:34,030 So this is one of the major advantage of genetic and the other advantage is by using genetic V can reuse 16 00:01:34,030 --> 00:01:34,440 the code. 17 00:01:34,480 --> 00:01:37,320 So the other advantage is called usability. 18 00:01:37,330 --> 00:01:43,750 Let's take an example let's create a class let's plus create a package in this a genetics project. 19 00:01:43,750 --> 00:01:45,500 So we'll create a package. 20 00:01:45,500 --> 00:01:47,560 Calm down basics. 21 00:01:47,650 --> 00:01:48,310 Strong 22 00:01:52,010 --> 00:01:53,720 dart genetics 23 00:01:56,780 --> 00:02:08,420 and head of create a class simply data so we have this class data and inside this data class are we're 24 00:02:08,420 --> 00:02:11,170 going to how we will have a private feel. 25 00:02:12,980 --> 00:02:20,610 Private shrink type data. 26 00:02:20,680 --> 00:02:27,260 Now let's create get those and set those for data and let's have constructor 27 00:02:36,050 --> 00:02:43,320 Soviet constructor and inside this construct let's fight and let's get the definition string data 28 00:02:47,130 --> 00:02:55,280 the data and finally the how do string implementation for this class. 29 00:02:56,730 --> 00:02:58,030 So heavily. 30 00:02:58,240 --> 00:02:58,800 Don 31 00:03:02,520 --> 00:03:05,660 our string data 32 00:03:09,420 --> 00:03:09,960 is 33 00:03:14,650 --> 00:03:23,740 data so data classes ready now let's create one more class to demonstrate the need for genetics. 34 00:03:23,870 --> 00:03:29,160 So let's create one class demo that mean 35 00:03:33,840 --> 00:03:34,760 inside this class. 36 00:03:34,760 --> 00:03:36,830 Let's create object of data glass 37 00:03:43,300 --> 00:03:46,950 new data and we have to pass the data inside it. 38 00:03:47,020 --> 00:03:49,070 And the type for that is strength. 39 00:03:49,330 --> 00:03:52,220 So we have to pass the data in string. 40 00:03:52,360 --> 00:04:01,510 So this is D 1. 41 00:04:01,520 --> 00:04:03,680 Now let's bring 42 00:04:07,160 --> 00:04:12,720 by invoking the two string and let's run this 43 00:04:21,270 --> 00:04:25,860 So data is debunked so everything is fine until now. 44 00:04:25,910 --> 00:04:34,550 But now suppose I want this data to be in Deja What do I do now. 45 00:04:34,550 --> 00:04:37,400 Should I replace the string as integer. 46 00:04:37,400 --> 00:04:45,490 Or then I will not be able to use the string or I would not have the data string. 47 00:04:46,000 --> 00:04:47,770 So what should I do. 48 00:04:47,770 --> 00:04:49,540 Should I play string as object. 49 00:04:49,540 --> 00:04:53,880 So let's do this because I want string as well as in digit objects. 50 00:04:53,950 --> 00:04:56,920 So I will replace this with object 51 00:05:03,310 --> 00:05:07,600 object so I replace it everywhere. 52 00:05:07,630 --> 00:05:14,530 Now inside this demo I can create one more object date. 53 00:05:14,590 --> 00:05:15,860 Daddy do. 54 00:05:16,060 --> 00:05:20,010 And this time I can pass in Deja do it 55 00:05:24,220 --> 00:05:25,200 right. 56 00:05:25,420 --> 00:05:31,170 And if I retrieve the data in data 57 00:05:33,670 --> 00:05:34,100 and 58 00:05:37,410 --> 00:05:41,810 Deven and dart get data. 59 00:05:41,830 --> 00:05:49,610 So as you can see that suppose I mistakenly crossed a Deven to end I actually wanted to cost. 60 00:05:49,730 --> 00:05:56,200 But the cost data back to end but I mistakenly I caused Deven to end 61 00:06:04,250 --> 00:06:08,220 dark get data OK. 62 00:06:12,730 --> 00:06:20,800 So as you can see combined it is not able to detect this mistake. 63 00:06:20,800 --> 00:06:21,790 Now let's run this 64 00:06:26,300 --> 00:06:29,480 so see what gift we got we got. 65 00:06:29,480 --> 00:06:31,050 Class cast exception. 66 00:06:31,070 --> 00:06:33,420 So this is not the solution. 67 00:06:33,590 --> 00:06:35,720 We want to go for right. 68 00:06:35,720 --> 00:06:43,920 So by replacing object object is not appropriate solution that we should go for now should I create 69 00:06:43,920 --> 00:06:51,180 one more class with the data field and having integer as its type yes we can do so. 70 00:06:51,180 --> 00:06:54,510 But next I want to have double as the data. 71 00:06:54,750 --> 00:07:01,400 So should I keep adding classes on answer a simple use genetics how to use genetics. 72 00:07:01,410 --> 00:07:09,490 Let's cut this as you can see this data class in this to make this data class as genetic type if you're 73 00:07:09,490 --> 00:07:18,660 going to use angler brackets to specify the type that meter so then how does had the formal type parameter 74 00:07:18,870 --> 00:07:25,260 d x as a place holder for the actual type that the middle provide. 75 00:07:25,260 --> 00:07:28,570 So we call this D a type that I do so this type. 76 00:07:28,600 --> 00:07:33,940 But I mean did provide a V for us to reuse the same order with any input right. 77 00:07:34,110 --> 00:07:42,450 So this D is a type parameter. 78 00:07:42,500 --> 00:07:51,230 Now I want the type of data to be anything so I will replace it with D. 79 00:07:52,820 --> 00:07:54,590 So now it can be anything 80 00:07:59,310 --> 00:07:59,550 so. 81 00:07:59,680 --> 00:08:04,250 And now this data it says is has become a genetic type. 82 00:08:04,260 --> 00:08:06,210 It's a genetic class. 83 00:08:06,270 --> 00:08:08,490 Now this data is genetic class. 84 00:08:08,490 --> 00:08:13,960 Now let's back to this demo class on this mean metal. 85 00:08:14,030 --> 00:08:21,980 Now let's create Batam address type references to this genetic type data but I'm a trice type of bottom 86 00:08:21,980 --> 00:08:29,000 address type is the barometer that provide information to the compiler that what type is it so that 87 00:08:29,030 --> 00:08:30,500 it can check the types. 88 00:08:30,500 --> 00:08:35,060 So that there's a data Deven I will say this is string 89 00:08:39,150 --> 00:08:42,500 and her so now 90 00:08:46,130 --> 00:08:48,230 the compiler know the type of the data. 91 00:08:48,260 --> 00:08:52,840 So we do not need to costed that compiler does this thing by itself. 92 00:08:52,860 --> 00:08:55,460 Now I can create objects open any data type. 93 00:08:55,460 --> 00:09:01,550 I don't need to write separate classes for that so I can have this as integer 94 00:09:06,640 --> 00:09:11,170 so integer is the bottom address type and add the right. 95 00:09:11,210 --> 00:09:18,100 You do not and you are not needed to specify the parameter based type but you have to specify this diamond. 96 00:09:18,100 --> 00:09:25,680 OPERATOR How what do you can also provide it with integer but this is not necessary to do 97 00:09:29,190 --> 00:09:39,150 so if and as you can see we are getting this error cannot cost string to end it knows what a type it 98 00:09:39,540 --> 00:09:43,020 it what what type it is off. 99 00:09:43,030 --> 00:09:51,760 So it is not letting us do can wanted to do wrong type and when I run this let's run this code let's 100 00:09:51,760 --> 00:09:52,870 bring data to 101 00:10:04,110 --> 00:10:06,830 and see so data is Dan 102 00:10:09,600 --> 00:10:18,030 one more important thing to keep in mind about genetics is that that this team mean anything they're 103 00:10:18,030 --> 00:10:27,310 using these as a genetic to create an instance of an object but we cannot do this if we have a static 104 00:10:27,310 --> 00:10:34,600 method or feel because genetic type parameters are only in school for an instance of the class that 105 00:10:34,600 --> 00:10:41,020 means instance method any instance fields of over class because static members and fields belong to 106 00:10:41,170 --> 00:10:43,570 each and every instance of the class. 107 00:10:43,630 --> 00:10:52,300 So if you had an instance of data just like here we are having one instance of string data as a string 108 00:10:52,330 --> 00:10:59,830 and data as integer so we have to Einsteins but a different data type then what exactly should the static 109 00:10:59,830 --> 00:11:03,670 method be using string or in Deja said Gondry decided. 110 00:11:03,670 --> 00:11:10,870 So this concept is only applicable for class instances hope you might have understood what's going on 111 00:11:10,870 --> 00:11:16,210 under the hood and it was a quick introduction about genetics. 112 00:11:16,210 --> 00:11:17,620 Hope you understood it. 113 00:11:17,770 --> 00:11:19,570 So now let's move to the next lecture.