1
00:00:00,420 --> 00:00:01,080
Welcome back.

2
00:00:01,320 --> 00:00:06,150
And this video, I would like to talk about a specific type of a class, which is a data class.

3
00:00:06,480 --> 00:00:08,490
So let's create a data class real quick.

4
00:00:08,790 --> 00:00:13,350
In order to create a data class, you can just go ahead and use the keyword data.

5
00:00:13,770 --> 00:00:20,790
And then you'll see that the class so it's inside of the class here, Cortland basics, that's at least

6
00:00:20,790 --> 00:00:25,950
how it's going to be called directly, but I want to call this one user.

7
00:00:26,400 --> 00:00:34,290
And in here, I have to at least add one parameter and I'm going to add, for example, the ID, which

8
00:00:34,290 --> 00:00:41,220
is going to be a long ID and a name which is going to be a string.

9
00:00:42,860 --> 00:00:46,380
Now I can use to start a class in order to create objects of it.

10
00:00:46,400 --> 00:00:48,920
So let's do that real quick here, user.

11
00:00:49,310 --> 00:00:55,520
And it's going to be a user one or the idea is going to be one and the name is going to be Dennis.

12
00:00:55,910 --> 00:00:57,830
So that's already a user object.

13
00:00:57,830 --> 00:01:01,880
Of course, we can call this one user one in order to be more precise.

14
00:01:02,120 --> 00:01:05,209
So that's how we create an object of a data class.

15
00:01:05,450 --> 00:01:08,750
Now, when creating the other classes, there are things that you need to consider.

16
00:01:08,960 --> 00:01:14,540
So the primary constructor must have at least one parameter so you can see if I get rid of that.

17
00:01:14,840 --> 00:01:18,770
Then we get an error here because we don't have any parameter in there.

18
00:01:18,950 --> 00:01:21,260
But as I said, one is the minimum.

19
00:01:21,590 --> 00:01:25,970
Then you need to assign them either as VAR or volume.

20
00:01:26,660 --> 00:01:32,660
So both the swine and other classes cannot be abstract, open, sealed or in their classes.

21
00:01:33,140 --> 00:01:34,970
So none of these things work.

22
00:01:35,180 --> 00:01:39,180
So you cannot go ahead and use open here in front of it.

23
00:01:39,200 --> 00:01:41,000
So as you can see, it's not going to accept that.

24
00:01:42,810 --> 00:01:47,910
In order to, you know, acts as a property, we can simply go ahead and use it like this, we can just

25
00:01:47,910 --> 00:01:52,170
say user one dog name, for example, and that will give us the name.

26
00:01:52,170 --> 00:01:54,620
In this case, it will give us Dennis.

27
00:01:54,630 --> 00:01:58,470
So we can, of course, check that print line name.

28
00:01:59,960 --> 00:02:00,860
So let's check it.

29
00:02:03,000 --> 00:02:04,710
And there we are it says, Dennis.

30
00:02:05,400 --> 00:02:06,900
OK, so that's how you can do it.

31
00:02:07,200 --> 00:02:15,570
Now let's say you want to assign a new value, so instead of having the I.D. one, you want to assign

32
00:02:15,780 --> 00:02:16,470
the value to.

33
00:02:17,400 --> 00:02:20,070
Well, the problem is that won't work because it's a vowel.

34
00:02:20,100 --> 00:02:20,370
Right?

35
00:02:20,380 --> 00:02:25,530
So when you hover over it, wall cannot be reassigned and you shouldn't reassign an ID.

36
00:02:25,980 --> 00:02:31,950
But maybe you want to be able to reassign the name so you want to change the name of a specific user.

37
00:02:32,310 --> 00:02:37,140
Then you can, of course, do so and replace that with, for example, Michael.

38
00:02:38,010 --> 00:02:38,340
All right.

39
00:02:38,340 --> 00:02:40,230
So that's going to be now.

40
00:02:40,240 --> 00:02:43,650
Michael User1 is not going to be Dennis anymore, but it's going to be Michael now.

41
00:02:44,370 --> 00:02:48,510
And then, of course, you can create new users any time.

42
00:02:49,560 --> 00:02:52,740
And you can also compare them, so let's say we have user to.

43
00:02:54,050 --> 00:03:00,950
So it would create a new user here of all user to is going to be a user object, which I give the idea

44
00:03:00,950 --> 00:03:07,400
of one and also the name of Michael Wright, because what I want to show you is that you can compare

45
00:03:07,400 --> 00:03:13,700
them so you can go ahead and compare user one equals.

46
00:03:14,790 --> 00:03:15,450
User two.

47
00:03:16,200 --> 00:03:20,370
All right, so because every object is of type any.

48
00:03:20,850 --> 00:03:23,280
At one point, so inherits from any.

49
00:03:23,550 --> 00:03:26,250
That's why we can use the equals function here.

50
00:03:26,670 --> 00:03:30,270
And alternatively, you can replace it with a double equals sign.

51
00:03:30,510 --> 00:03:32,280
So both versions are fine.

52
00:03:32,640 --> 00:03:34,350
And this will print.

53
00:03:34,380 --> 00:03:34,770
True.

54
00:03:34,980 --> 00:03:37,830
We can, of course, test that and see if that's actually the case.

55
00:03:39,600 --> 00:03:40,370
And there you are.

56
00:03:40,400 --> 00:03:44,310
That's true, because both have the same content, right?

57
00:03:44,310 --> 00:03:47,910
So in both cases, the user ID is one and the name is Michael.

58
00:03:48,810 --> 00:03:54,630
OK, so of course, here we can follow the instruction and just use a double equal sign, which will

59
00:03:54,630 --> 00:03:55,830
result in true as well.

60
00:03:58,840 --> 00:04:07,790
Other classes also have a two string method, so the same as other classes as well, so user details

61
00:04:08,450 --> 00:04:09,890
colon and a user.

62
00:04:10,250 --> 00:04:19,370
So just using this as going to work totally fine because our data class has a two string method underlying

63
00:04:19,370 --> 00:04:26,660
it because every class is inheriting any and one point, and that's why it's available in there as well.

64
00:04:27,730 --> 00:04:30,010
Another cool function is the copy function.

65
00:04:30,130 --> 00:04:34,430
So if you want to copy one object to another, you can do that easily.

66
00:04:34,450 --> 00:04:40,030
So let's say we have this updated user object, which will be of type user.

67
00:04:40,810 --> 00:04:48,160
And here I'm just saying, OK, I want to copy user one so you can just go ahead and do like this or

68
00:04:48,490 --> 00:04:52,720
you can copy its contents except for the variables that you want to change.

69
00:04:52,750 --> 00:04:56,620
So let's say I want to change that name to Dennis Potuto.

70
00:04:56,920 --> 00:05:03,400
So user one will still be Michael, but now our updated user will be Dennis, one user, but will also

71
00:05:03,400 --> 00:05:06,280
have the idea of one, even though it usually should be unique.

72
00:05:06,520 --> 00:05:08,770
But I think in this case, it's going to be fine.

73
00:05:09,070 --> 00:05:14,590
So let's print our updated user and let's see what we get there.

74
00:05:15,890 --> 00:05:22,670
And by the way, we should maybe also print our user one just to see the difference between the two.

75
00:05:24,840 --> 00:05:25,860
All right, so there we are.

76
00:05:26,580 --> 00:05:29,120
It says then, is it from the top there than we had through this?

77
00:05:29,130 --> 00:05:35,090
Was this comparison that we had and then user details, that's this one here where it says user I.D.

78
00:05:35,100 --> 00:05:36,600
one name Michael.

79
00:05:36,840 --> 00:05:42,600
And then we have one user, which is our user, one which has the idea of one and the name of Michael

80
00:05:42,600 --> 00:05:47,790
and the other user, which is our updated user, which has the same ID and a different name.

81
00:05:48,090 --> 00:05:51,170
Now, in this case, it might be redundant.

82
00:05:51,180 --> 00:05:57,240
It might seem stupid to do that, but not all data classes are as basic as we have it here, with just

83
00:05:57,240 --> 00:05:59,620
two variables or two parameters.

84
00:05:59,640 --> 00:06:04,470
Imagine a data class with, let's say, seven different variables or parameters here.

85
00:06:04,950 --> 00:06:09,930
Then it's already a very different story because then it might really make sense to just change one

86
00:06:09,930 --> 00:06:11,940
thing and then copy the rest.

87
00:06:12,480 --> 00:06:15,660
OK, so let's look at our updated user.

88
00:06:16,470 --> 00:06:18,600
The updated user has an ID and a name.

89
00:06:18,870 --> 00:06:24,690
Now what we can do is we can get its components so we can go ahead and.

90
00:06:25,730 --> 00:06:26,990
Good component, number one.

91
00:06:27,530 --> 00:06:31,340
So, user one dot or in this case, it was updated user.

92
00:06:32,340 --> 00:06:42,180
That component one will give us the first component, so to speak, this one will print I.D. one and

93
00:06:42,180 --> 00:06:49,260
then print line updated user component two will print.

94
00:06:51,120 --> 00:06:51,870
Then this you to.

95
00:06:55,110 --> 00:06:56,550
OK, so this is the.

96
00:06:57,500 --> 00:07:02,900
Feature that you can use, another cool thing is that we can use deconstruction, so let's look at deconstruction,

97
00:07:02,900 --> 00:07:12,560
so I have this idea and the name variable, so I have these two variables that I want to make dependent

98
00:07:12,560 --> 00:07:14,240
on our updated user.

99
00:07:15,170 --> 00:07:21,710
So what will happen now is that is going to take the ID and the name from updated user and it's going

100
00:07:21,710 --> 00:07:23,950
to store them in separate variables.

101
00:07:23,970 --> 00:07:29,990
So it's the same thing as going ahead and saying it is equal to updated user dot ID.

102
00:07:31,470 --> 00:07:36,480
And while I know your name is updated user name.

103
00:07:37,110 --> 00:07:44,250
Now, of course, in our case, it's complaining because name already existed up here, so let's get

104
00:07:44,250 --> 00:07:44,700
rid of this.

105
00:07:45,800 --> 00:07:46,460
And now.

106
00:07:47,660 --> 00:07:54,680
We can use this functionality so now we can go ahead and create variables, all of the different attributes

107
00:07:54,680 --> 00:07:56,450
that are within an object.

108
00:07:56,780 --> 00:07:59,660
And I can, of course, go ahead and print those.

109
00:07:59,660 --> 00:08:05,780
So ID is going to be ID and name is going to be.

110
00:08:06,820 --> 00:08:07,210
Name.

111
00:08:10,660 --> 00:08:11,350
All right, so.

112
00:08:12,430 --> 00:08:16,720
This will print, Heidi, is one name is going to be Dennis Produto.

113
00:08:16,930 --> 00:08:17,890
So let's test it.

114
00:08:19,500 --> 00:08:22,950
And there we are, so it says IDs, one and name is then upon you, though.

115
00:08:23,490 --> 00:08:23,820
All right.

116
00:08:23,820 --> 00:08:29,790
So this was just a little introduction into beta classes, and we're going to use data classes because

117
00:08:29,790 --> 00:08:36,480
there's just very powerful, very basic classes, which are very limited in their functionality.

118
00:08:36,480 --> 00:08:37,860
But that is exactly what we need.

119
00:08:37,860 --> 00:08:44,520
Sometimes we just don't want to have all of this overhead and all of this additional code, and we just

120
00:08:44,520 --> 00:08:50,520
want to have a clean and simple object type and therefore data classes are amazing.

121
00:08:51,330 --> 00:08:52,860
All right, so see you in the next video.