1 00:00:01,280 --> 00:00:06,890 Come back in this video, we are going to change our culture a little bit and prepare our first app 2 00:00:07,010 --> 00:00:12,680 to actually do what we wanted to do, and that is to not display Helloworld, but actually our name. 3 00:00:13,130 --> 00:00:17,180 So therefore, let's get started and look at what the code does for us. 4 00:00:17,480 --> 00:00:19,310 So let's go to the main activity. 5 00:00:19,320 --> 00:00:24,590 You can either go to it from here and if you by accident closed it, for example, you can still find 6 00:00:24,590 --> 00:00:25,670 it in your app. 7 00:00:25,940 --> 00:00:30,710 Java, then the name of your package and then main activity. 8 00:00:31,310 --> 00:00:36,230 So can see this is the name of the package that we have selected to when we created the project. 9 00:00:36,590 --> 00:00:39,150 And you can also find that package name up here. 10 00:00:39,200 --> 00:00:41,270 So you wrote that artist up my first app. 11 00:00:41,600 --> 00:00:43,550 This just says that this file. 12 00:00:43,640 --> 00:00:48,470 All of the code that is in here belongs to the package of EU, the tutorials that my first app. 13 00:00:49,220 --> 00:00:54,590 Then you find this import keyword and import keyboard has three dots in it, which means there is something 14 00:00:54,590 --> 00:00:57,950 behind it so you can click on it and then this pops up. 15 00:00:58,220 --> 00:01:06,880 You can see here Android Acts App Compered Dot App Dot app activity, which is a library or a namespace, 16 00:01:06,890 --> 00:01:08,090 however you want to call it. 17 00:01:08,300 --> 00:01:15,140 Both words are fine, which basically means that there is a lot of code behind it, and it allows us 18 00:01:15,140 --> 00:01:16,760 to use its functionality. 19 00:01:17,180 --> 00:01:24,650 So if we delete this line of code, then suddenly our program starts to not work anymore. 20 00:01:24,770 --> 00:01:26,360 So we get an error you can see here. 21 00:01:26,360 --> 00:01:33,560 It's underlined here does main activity, so it doesn't understand what this override method does because, 22 00:01:33,560 --> 00:01:36,110 well, we never had set it up. 23 00:01:36,290 --> 00:01:41,450 So that's something that is set up in this app combat activity, which basically is a lot of code that 24 00:01:41,450 --> 00:01:47,000 somebody else wrote for us and we can now reuse in order to not have to write that code manually ourself. 25 00:01:47,390 --> 00:01:51,140 So we should be thankful to them because they really save us a lot of time. 26 00:01:51,170 --> 00:01:52,490 So thanks a lot for doing that. 27 00:01:53,090 --> 00:01:58,520 Now we are using this app activity here again, you can see, and that is only possible because we have 28 00:01:58,520 --> 00:01:59,800 this input now. 29 00:01:59,810 --> 00:02:01,400 The same goes for this bundle. 30 00:02:01,400 --> 00:02:08,210 Here you can see Save the Instance bundle what we're using this bundle code in our class main activity 31 00:02:08,210 --> 00:02:08,660 as well. 32 00:02:08,900 --> 00:02:14,870 So that's why we have these imports and we're going to add more imports later on, which will then allow 33 00:02:14,870 --> 00:02:20,750 us to use different kinds of codes and functionality, which is very powerful. 34 00:02:21,170 --> 00:02:26,390 If you want to understand more what's behind this app combat activity, you can just hold your command 35 00:02:26,390 --> 00:02:34,580 key or control key and then click on to the name here and you will find that it opens up this declaration. 36 00:02:34,580 --> 00:02:39,650 For this file, you can see it's called App Combat Activity that Java, so it's a Java file, it's not 37 00:02:39,650 --> 00:02:40,610 a cut and file. 38 00:02:40,970 --> 00:02:46,610 You can also see that byte structure, so the code is slightly differently written, so you have to 39 00:02:46,610 --> 00:02:48,260 access modifiers everywhere. 40 00:02:48,500 --> 00:02:50,990 You don't even need to understand what that is at this point. 41 00:02:50,990 --> 00:02:54,860 So you can see there are hundreds of lines of code basically allowing us to use them. 42 00:02:55,100 --> 00:02:56,840 And then the same goes for this bundle. 43 00:02:56,990 --> 00:03:02,030 You can just click on to it and then you can well access it to make changes to it, but I'm not going 44 00:03:02,030 --> 00:03:03,020 to do that for now. 45 00:03:03,560 --> 00:03:05,570 So then this is the important part. 46 00:03:05,660 --> 00:03:08,660 This is basically where our own code starts. 47 00:03:08,780 --> 00:03:11,750 So we have our main activity, which is a class. 48 00:03:11,870 --> 00:03:16,910 So then we have this class keyword and we're going to look deeper into what a class is later on. 49 00:03:16,910 --> 00:03:21,200 But generally it's going to be the container for our code. 50 00:03:21,320 --> 00:03:26,330 It's going to hold our code and it will allow us to execute some code. 51 00:03:26,930 --> 00:03:33,890 So we call this class main activity and it has this colon here, then Epcot combat activity, which 52 00:03:33,890 --> 00:03:37,330 basically just means that it inherits from app competitively team. 53 00:03:37,340 --> 00:03:41,900 And we're going to see what inheritance is later on once we get to object oriented programming. 54 00:03:42,200 --> 00:03:43,730 It would lead way too far for now. 55 00:03:44,030 --> 00:03:49,610 What's really important is that we have this on create method, which will be called once our main activity 56 00:03:49,910 --> 00:03:51,380 is going to be created. 57 00:03:51,740 --> 00:03:54,710 And by the way, an activity is just a screen. 58 00:03:54,950 --> 00:04:00,560 So if you have multiple screens in your application, for example, the login screen and then the profile 59 00:04:00,560 --> 00:04:04,550 screen and so forth, all of those would be different activities. 60 00:04:05,210 --> 00:04:11,210 And we're going to create multiple different activities later on when we create more complex applications. 61 00:04:11,450 --> 00:04:13,130 But that's what you just need to remember. 62 00:04:13,130 --> 00:04:15,050 For now, activity equals screen. 63 00:04:15,620 --> 00:04:19,040 And then we have this override function on create. 64 00:04:19,399 --> 00:04:21,589 So this is a fun, which means a function. 65 00:04:21,620 --> 00:04:25,430 This is not about having fun or something like that, even though you can have fun with functions, 66 00:04:25,670 --> 00:04:29,630 but this is our function which is overridden on create. 67 00:04:29,630 --> 00:04:37,130 So basically, it just means there is some on method inside of the combat activity and we are overwriting 68 00:04:37,130 --> 00:04:38,480 it with our own code. 69 00:04:39,260 --> 00:04:41,930 So what you're saying, OK, we're going to run our own code. 70 00:04:42,320 --> 00:04:46,400 Then there is a bundle passed here and that's something we're not going to cover for now. 71 00:04:46,760 --> 00:04:52,450 And the super method is called so super on create, for instance, which just means that whatever combat 72 00:04:52,520 --> 00:04:57,230 activity wants to execute by default in aggregate is being executed. 73 00:04:57,650 --> 00:04:59,130 And then comes the interesting part. 74 00:04:59,150 --> 00:05:00,440 That's where we. 75 00:05:00,580 --> 00:05:07,000 Actually can make changes, so this is going to be the content view which actually sets the content 76 00:05:07,150 --> 00:05:07,840 of the View. 77 00:05:08,140 --> 00:05:09,100 Who would have guessed it? 78 00:05:09,400 --> 00:05:15,690 And to what we're saying here is please set the content of our layout activity main. 79 00:05:16,150 --> 00:05:17,540 And where do you find this file? 80 00:05:17,560 --> 00:05:20,560 You find it under our dot layout that activity, mate. 81 00:05:21,040 --> 00:05:22,030 So where is that? 82 00:05:22,270 --> 00:05:24,820 Well, our stance for resources. 83 00:05:25,270 --> 00:05:30,940 So if you go over here, you will find this press folder not to generate it one, but the other one. 84 00:05:31,420 --> 00:05:33,700 And then you will find a folder called layout. 85 00:05:34,000 --> 00:05:36,970 And that's exactly where our activity main file is. 86 00:05:37,360 --> 00:05:42,820 So we're just saying, OK, set the view to have the contents of our activity main, which means that 87 00:05:42,820 --> 00:05:46,990 this is the XML file which will be actually displayed on our application. 88 00:05:47,350 --> 00:05:49,030 So let's change that up a little bit. 89 00:05:49,270 --> 00:05:51,620 First of all, click on this helloworld here. 90 00:05:51,700 --> 00:05:54,430 You can either click on it from the componentry here. 91 00:05:54,430 --> 00:05:59,830 On the left hand side, just click on this text view, or you can access it directly via the designer 92 00:05:59,830 --> 00:06:00,100 view. 93 00:06:00,670 --> 00:06:06,430 So here, let's click on this helloworld and then on the right hand side in the attributes, you can 94 00:06:06,820 --> 00:06:09,090 go to declared attributes. 95 00:06:09,100 --> 00:06:11,800 OK, so there are a bunch of different settings. 96 00:06:11,800 --> 00:06:16,030 You can go to common attributes, two declared attributes and so forth. 97 00:06:16,270 --> 00:06:23,260 So I'm just going to go over to the declared attributes and we can declare the Helloworld to display 98 00:06:23,260 --> 00:06:23,890 something else. 99 00:06:24,070 --> 00:06:27,610 So here I'm just going to say hello, Dennis and press enter. 100 00:06:28,180 --> 00:06:31,720 And you can see that now the text should say Hello, Dennis. 101 00:06:32,140 --> 00:06:36,700 We'll get a little exclamation mark, but we're going to ignore that for now, it would go too far at 102 00:06:36,700 --> 00:06:37,220 this point. 103 00:06:37,300 --> 00:06:38,920 We're going to see what that means later on. 104 00:06:39,580 --> 00:06:41,560 But now it just says, Hello, Dennis. 105 00:06:42,070 --> 00:06:43,300 But I'm not very happy with that. 106 00:06:43,300 --> 00:06:45,690 I would like this to look a little different. 107 00:06:45,700 --> 00:06:47,200 I would like it to be bigger. 108 00:06:47,920 --> 00:06:55,150 So in order to change that, you can go over to your common attributes and you can go to text appearance. 109 00:06:55,720 --> 00:06:59,830 And here you can change, for example, the font family if you want it to look differently. 110 00:07:00,430 --> 00:07:03,580 Here there are serif, black, medium light and so forth. 111 00:07:04,270 --> 00:07:05,650 You could change the typeface. 112 00:07:06,040 --> 00:07:12,070 But what I'm interested in is the text size, so I'm going to change that to 25 ESP, for example, 113 00:07:12,580 --> 00:07:16,450 ESP here by stands for scale independent pixels. 114 00:07:18,300 --> 00:07:25,070 Which just means that it's going to look more or less the same, no matter which device you are using, 115 00:07:25,530 --> 00:07:29,040 because pixels are different on each device. 116 00:07:29,040 --> 00:07:35,340 So let's say you have a big screen, then each pixel is going to be look bigger, right? 117 00:07:35,730 --> 00:07:42,810 But SP, what it tries to do is it tries to make it independent of the size of the screen or the amount 118 00:07:42,810 --> 00:07:44,460 of pixels that the screen has. 119 00:07:44,700 --> 00:07:48,040 This tech should always look the same, or more or less the same. 120 00:07:48,060 --> 00:07:53,100 We'll never be exactly the same, but here at the top you can even select the device and you can see 121 00:07:53,100 --> 00:07:53,900 the DPI. 122 00:07:54,150 --> 00:08:01,110 So now if we look at it on a phone that has a different dpi, sort of, let's say, five hundred sixty, 123 00:08:01,110 --> 00:08:04,530 for example, you can see the text still looks more or less the same. 124 00:08:05,250 --> 00:08:05,690 OK. 125 00:08:05,910 --> 00:08:10,950 So I'm going to go back to Pixel four, which is the device that we're using here at the top. 126 00:08:11,220 --> 00:08:13,740 So that's how the text is going to look like now. 127 00:08:13,740 --> 00:08:19,020 Let's run the application, so click on this button here at the top and see what's going to happen. 128 00:08:20,610 --> 00:08:23,250 And there we are, my first EP, says Hello, Dennis. 129 00:08:23,530 --> 00:08:27,690 Of course it shouldn't say hello, Dennis, in your case, I would like you to enter your own name here. 130 00:08:28,290 --> 00:08:31,810 Now you can, of course, also write something entirely differently. 131 00:08:31,830 --> 00:08:37,530 Maybe even in your native language, if English isn't your native language, then just change that to 132 00:08:37,530 --> 00:08:42,330 whatever text you want to display and try it once again with a common attributes. 133 00:08:42,330 --> 00:08:45,260 Here, for example, you could change to color as well. 134 00:08:45,270 --> 00:08:48,670 If you don't want to use black, you could use red, for example. 135 00:08:48,700 --> 00:08:51,720 I really love the color red, so change that. 136 00:08:51,960 --> 00:08:57,750 Rerun the application and then go over here and you will see that it says hello, diners in red now. 137 00:08:59,080 --> 00:09:05,950 OK, so that's pretty much it for this video, we have set up our first on changes when as to what the 138 00:09:05,950 --> 00:09:12,370 main activity does and what all of this stuff more or less does, even though we are going to go into 139 00:09:12,370 --> 00:09:14,830 a lot more depth into what is happening here. 140 00:09:14,830 --> 00:09:15,670 So no worries. 141 00:09:15,670 --> 00:09:20,110 If you don't understand what's up here, the only thing that you needed to understand is that there 142 00:09:20,110 --> 00:09:26,590 are packages you can import different libraries that allow you to then use their code. 143 00:09:26,740 --> 00:09:32,620 And we have this container, which basically is going to take care of what we can see on the screen 144 00:09:32,620 --> 00:09:37,570 by setting the XML file that we have here that we can then edit. 145 00:09:37,570 --> 00:09:41,770 And by the way, if you want to jump through this file directly, you can hold the control key. 146 00:09:41,770 --> 00:09:44,080 Click on it and it will jump to this activity. 147 00:09:44,080 --> 00:09:46,780 Main example and just a very quick one. 148 00:09:46,780 --> 00:09:51,700 We're not going to change anything there, but this design here is just one way of looking at this. 149 00:09:52,040 --> 00:09:57,490 We're going to work a lot with the code, and this is how the code is and we're going to see what all 150 00:09:57,490 --> 00:09:59,200 of that means later on in the course. 151 00:10:00,130 --> 00:10:02,870 But you will probably already see it, says Halo, then is here. 152 00:10:02,890 --> 00:10:07,360 It says that there is a certain text color, which is this red, and you see that there's a certain 153 00:10:07,360 --> 00:10:13,810 text size that we have defined and that is basically representing what we see right here. 154 00:10:16,150 --> 00:10:20,350 All right, so see you in the next video where we're going to create a people counter app.