1 00:00:00,390 --> 00:00:01,180 Hi everyone. 2 00:00:01,260 --> 00:00:04,980 So now it's time to implement the main activity class. 3 00:00:04,980 --> 00:00:10,930 So first of all just open the app folder and then open the rest folder here inside these terrorist folder 4 00:00:10,950 --> 00:00:16,700 we have this layer folder open it and here you can see the content underlined when that example just 5 00:00:16,700 --> 00:00:19,580 publicly on the spot in order to open this file here. 6 00:00:19,890 --> 00:00:21,940 So this is our content underline minute examen. 7 00:00:21,950 --> 00:00:27,310 And you can see that inside this componentry the constraint lay out a layout is actually the main way 8 00:00:27,310 --> 00:00:28,160 out here. 9 00:00:28,440 --> 00:00:31,440 So at the bottom here you can see this text tap. 10 00:00:31,470 --> 00:00:35,970 Just click on it so you can see that we have actually our concerns they are. 11 00:00:36,090 --> 00:00:38,130 So I don't want a constraint there. 12 00:00:38,180 --> 00:00:39,700 You want a scroll view. 13 00:00:39,750 --> 00:00:40,280 OK. 14 00:00:40,440 --> 00:00:46,440 So let's actually change at this opening tag here you can see the name is Android that supports that 15 00:00:46,440 --> 00:00:48,350 constraint that constraints play out. 16 00:00:48,360 --> 00:00:50,210 So just delete this name here. 17 00:00:50,230 --> 00:00:52,770 I just step in here scroll view. 18 00:00:52,940 --> 00:00:56,030 OK so this is going to be the pattern to play out. 19 00:00:56,110 --> 00:01:00,140 And now let's actually give an ID to this scroll view. 20 00:01:00,140 --> 00:01:04,800 So before the alien tag here of this scroll view let's create a new line. 21 00:01:04,820 --> 00:01:10,260 Just type in here ID and choose and sign Plus Id slash. 22 00:01:10,540 --> 00:01:12,630 And he had to step in here. 23 00:01:12,660 --> 00:01:18,420 The idea is going to be scroll view actually scroll view right. 24 00:01:18,430 --> 00:01:20,270 So this is going to be the ID. 25 00:01:20,440 --> 00:01:22,860 Now let's go to the main activity class here. 26 00:01:22,960 --> 00:01:27,250 So inside these Apfel that open the stub a folder and then open this package. 27 00:01:27,340 --> 00:01:31,630 And here you can see the main activity class doubleclick on this file here in order to make you know 28 00:01:31,700 --> 00:01:32,730 that all of these files. 29 00:01:32,920 --> 00:01:37,820 Now let's double click on this tab here an activity that job in order to make this area right there. 30 00:01:38,080 --> 00:01:39,880 So this is our main activity class. 31 00:01:39,970 --> 00:01:47,290 Let's go to this class let's actually here create some valuables inside this main activity class. 32 00:01:47,320 --> 00:01:51,420 So the first variable is going to be a type database handler right. 33 00:01:51,430 --> 00:01:58,660 So just step here private database handler database handler semicolon create another variable of type 34 00:01:58,660 --> 00:02:07,930 double so private double and the name of this value is going to be total total price total martial arts 35 00:02:07,930 --> 00:02:13,950 price total martial arts price semicolon. 36 00:02:14,050 --> 00:02:21,600 Now let's create actually a valuable or five scroll view so private scroll view scroll view semicolon 37 00:02:22,510 --> 00:02:29,520 and here because I want to actually put the martial art objects as buttons inside our scroll view in 38 00:02:29,520 --> 00:02:30,630 the main activity. 39 00:02:30,970 --> 00:02:38,180 I want to specify that each martial arts button is going to take only a half of the view of the screen. 40 00:02:38,500 --> 00:02:40,880 So just typing here private's it. 41 00:02:41,200 --> 00:02:44,950 Martial art martial art button 42 00:02:48,250 --> 00:02:49,230 semi-hollow. 43 00:02:49,510 --> 00:02:55,690 So here let's go to this uncreate method and let's initialize our valuables that we declared inside 44 00:02:55,690 --> 00:02:56,520 the class. 45 00:02:56,530 --> 00:03:02,400 I mean I think the first value is going to be database handler assignment operator new database handler. 46 00:03:02,440 --> 00:03:03,050 That's it. 47 00:03:03,220 --> 00:03:06,850 And here in say the prentices we just have to pass the context. 48 00:03:06,850 --> 00:03:11,190 The context is main activity that this semicolon. 49 00:03:11,530 --> 00:03:14,440 So now let's initialize this total martial arts prize. 50 00:03:14,470 --> 00:03:20,260 So notice that these variables that we created inside this class are actually instance variables and 51 00:03:20,260 --> 00:03:23,090 instance variables have default values. 52 00:03:23,110 --> 00:03:23,580 OK. 53 00:03:23,830 --> 00:03:28,870 So when I say initialize this means that you want to assign my own value to these variables. 54 00:03:29,080 --> 00:03:35,050 So let's pass the value zero point zero here let's assign this value to these rowdier but total total 55 00:03:35,050 --> 00:03:38,940 Musharraf's price and let's initialises this scroll view. 56 00:03:38,980 --> 00:03:45,830 Assignment operator let's cast this object through to a scroll you object find view by Id find viewpoint 57 00:03:45,910 --> 00:03:49,230 ID or that ID that scurvy. 58 00:03:49,660 --> 00:03:56,260 So notice that we actually created this idea here inside that content and then I mean it is I and if 59 00:03:56,260 --> 00:04:02,750 I go to this fight here you can see that you specified an ID for the scroll view here. 60 00:04:02,800 --> 00:04:04,760 So let's go back to the main activity class. 61 00:04:04,780 --> 00:04:11,840 So here I can say scroll view scroll view sometimes the autocomplete feature of Android studio is nothing 62 00:04:11,890 --> 00:04:16,400 to help you to for example refer to an SMS to a specific ID. 63 00:04:16,470 --> 00:04:20,590 So in that case you just need to manually write that idea here. 64 00:04:20,800 --> 00:04:27,610 Like the style scroll you and then here I need to initialize the mouse in order to actually calculate 65 00:04:27,640 --> 00:04:29,500 the width of the screen. 66 00:04:29,650 --> 00:04:35,140 We need to create a variable of type point so to step in here point and the name of this variable is 67 00:04:35,140 --> 00:04:43,070 going to be screen with screen which is I mean operator new point so at the end of her statement let's 68 00:04:43,070 --> 00:04:51,800 put a semicolon here and let's just type it here get window manager get default display that good size 69 00:04:52,250 --> 00:04:56,690 and let's pass this screen to this valuable here. 70 00:04:56,690 --> 00:04:59,110 So let's change the screen to screen size. 71 00:04:59,120 --> 00:05:01,410 Actually it's more meaningful here. 72 00:05:01,640 --> 00:05:02,660 So the screen size. 73 00:05:02,780 --> 00:05:05,550 Let's change this one to also screen size. 74 00:05:05,630 --> 00:05:10,810 Because here we want to first get the screen size and then we can get the width of the screen. 75 00:05:10,910 --> 00:05:11,400 OK. 76 00:05:11,630 --> 00:05:17,140 So first we have a variable of a point and then we want to get the screen size by just calling to get 77 00:05:17,150 --> 00:05:22,610 window manager to get the part display that gets size so the size is going to be assigned to this screen 78 00:05:22,610 --> 00:05:24,410 size variable here. 79 00:05:24,440 --> 00:05:26,040 Now I can get that screen with. 80 00:05:26,050 --> 00:05:31,090 So now let's refer to our martial art Potten with assignment operator. 81 00:05:31,190 --> 00:05:38,820 So now we have the screen size so the screen size that X semicolon that that's now the width of the 82 00:05:38,820 --> 00:05:43,100 screen is actually assigned to this monitor that button. 83 00:05:43,250 --> 00:05:47,830 But now we want to divide the width of the screen by two. 84 00:05:47,870 --> 00:05:52,780 So this means that the value that is going to be assigned to this variable marshal that button which 85 00:05:53,120 --> 00:05:58,340 is actually half the value of the half of the screen OK half of that half of the width of the screen 86 00:05:58,340 --> 00:05:58,980 actually. 87 00:05:59,180 --> 00:05:59,970 Right. 88 00:06:00,080 --> 00:06:05,240 So this means that I want my button to take half of the width of this screen. 89 00:06:05,600 --> 00:06:14,360 And finally we need to actually call the modify user interface modify user interface and then put a 90 00:06:14,360 --> 00:06:16,270 pair of Prentice's here semi-colon. 91 00:06:16,700 --> 00:06:25,820 So now I told you that root objects are going to be represented as buttons to the user inside the content 92 00:06:25,850 --> 00:06:32,030 and they let me index them and so this means that we need to create a subclass of button called martial 93 00:06:32,090 --> 00:06:38,930 art Potin so that we can actually provide some specific features for that button. 94 00:06:39,050 --> 00:06:40,910 So let's create a new class for that. 95 00:06:40,910 --> 00:06:43,400 Let's open the Android view here. 96 00:06:43,790 --> 00:06:48,350 So you know how to do that you just click on a view at the top to the windows and then project. 97 00:06:48,590 --> 00:06:55,910 And here just open this Joe a folder and then you just select this package directly cut it new and then 98 00:06:56,480 --> 00:06:58,370 just click on jobs class. 99 00:06:58,490 --> 00:06:58,970 OK. 100 00:06:59,150 --> 00:07:01,160 So for the name of the class here. 101 00:07:01,280 --> 00:07:02,250 Just step in here. 102 00:07:02,270 --> 00:07:10,270 Martial arts martial art but in martial arts and so this is the class here don't change anything just 103 00:07:10,310 --> 00:07:10,610 the kind. 104 00:07:10,650 --> 00:07:11,750 OK. 105 00:07:12,090 --> 00:07:15,940 So this is our martial art bottom class right. 106 00:07:15,960 --> 00:07:19,370 Let me just double click on the top here in order to make this area wider. 107 00:07:19,440 --> 00:07:24,610 So here because we want to create a subclass of Potten So we want the same button. 108 00:07:24,670 --> 00:07:28,980 Ok but I want to add some extra features to that button. 109 00:07:29,040 --> 00:07:36,390 So this means that our class marshal of the button must inherit from the app compact button class so 110 00:07:36,390 --> 00:07:42,090 I can say here extends app compact button. 111 00:07:42,390 --> 00:07:48,370 So this means that now our class marshal button is actually a subclass of the bottom class in Android. 112 00:07:48,660 --> 00:07:52,250 So let's go into the curly braces of this class first. 113 00:07:52,290 --> 00:07:59,350 Let's create a variable of type martial arts suggests they can hear Private martial art and the name 114 00:07:59,350 --> 00:08:05,030 of this valuable is martial art object martial art object semi-colon. 115 00:08:05,290 --> 00:08:08,960 Now let's create a constructor for this class. 116 00:08:08,960 --> 00:08:14,650 So just sitting here Puplick martial arts Potten put a pair of Prentice's here. 117 00:08:14,650 --> 00:08:23,800 First we need to specify the context here context comma and then we need to specify actually an argument 118 00:08:23,830 --> 00:08:27,510 or a perimeter in order to initialize or marshal or object body. 119 00:08:27,530 --> 00:08:33,990 But in this value actually so I can't say martial art martial arts. 120 00:08:34,120 --> 00:08:34,700 Right. 121 00:08:35,030 --> 00:08:42,070 So now let's open and close this constructor by using these curly braces inside the constructor. 122 00:08:42,180 --> 00:08:48,830 First need to call the constructor of the superclass which is going to be the app compatibility in class. 123 00:08:48,830 --> 00:08:49,530 Right. 124 00:08:49,580 --> 00:08:54,430 So I can say super And then we need to pass the context. 125 00:08:54,620 --> 00:08:55,740 That's it. 126 00:08:55,760 --> 00:08:57,960 Right now you can see that we have no errors. 127 00:08:58,190 --> 00:09:03,080 And finally we can initialize our instance variables to marshal object. 128 00:09:03,080 --> 00:09:06,080 Assignment operator martial art semi-colons. 129 00:09:06,290 --> 00:09:11,360 I am assigning this argument to this instance variable a martial art object. 130 00:09:11,360 --> 00:09:15,260 Now let's create some Kjetil my fits so I can say public. 131 00:09:15,800 --> 00:09:21,890 And the first method is going to actually turn a string by the way that is going to represent the color 132 00:09:21,920 --> 00:09:23,680 of that martial art. 133 00:09:23,690 --> 00:09:32,980 So I can't say public strange return or get martial art color get that color and then put a pair of 134 00:09:32,980 --> 00:09:36,510 panties here open and close this method by using these curly braces. 135 00:09:36,580 --> 00:09:38,260 And here's just three turn. 136 00:09:38,460 --> 00:09:45,410 Marshall object that color that actually gets rid of color right semi-colon. 137 00:09:45,700 --> 00:09:52,250 Let's create another method so public and here this time I want to return the modular price. 138 00:09:52,320 --> 00:09:58,450 So the return type of this method is going to be double the day of this it is going to be get Marshall 139 00:09:58,590 --> 00:10:04,820 Price get Mosteller price and put a pair of parenthesis here. 140 00:10:05,010 --> 00:10:15,470 Open and close this by using these curly braces return Marshall object that gets Marshall Price semicolon. 141 00:10:15,550 --> 00:10:16,370 So that's it. 142 00:10:16,630 --> 00:10:19,900 Let's go back to our main activity class here. 143 00:10:19,900 --> 00:10:22,280 So this is our master class right. 144 00:10:22,540 --> 00:10:28,150 So let's go back out toward me and I give the class here and let's provide an implementation let's create 145 00:10:28,210 --> 00:10:32,760 a method called modify user interface here inside our class. 146 00:10:32,800 --> 00:10:38,950 So after the in curly brace of these uncreate method I'm going to create that method here so I'm going 147 00:10:38,950 --> 00:10:45,740 to say private's void the name of this if it is modify use interface just with a set of practices you 148 00:10:46,100 --> 00:10:49,360 open and close this method by using these curly braces here. 149 00:10:49,370 --> 00:10:52,030 So now let's pro-white an implementation for this method.