1 00:00:00,300 --> 00:00:00,770 OK. 2 00:00:00,960 --> 00:00:03,430 So button ok. 3 00:00:03,520 --> 00:00:07,640 PTEN second activity. 4 00:00:08,420 --> 00:00:08,940 OK. 5 00:00:08,940 --> 00:00:14,580 Assignment operator and then here I can actually cast this object to a button object. 6 00:00:14,580 --> 00:00:22,020 So button find view by ID or that ID that PTEN second activity. 7 00:00:22,020 --> 00:00:22,850 OK. 8 00:00:23,760 --> 00:00:26,840 So now let me explain some concepts here. 9 00:00:26,880 --> 00:00:34,440 As you can see here this is our main activity and this activity actually extends this act of compact 10 00:00:34,440 --> 00:00:34,890 activity. 11 00:00:34,890 --> 00:00:35,380 OK. 12 00:00:35,580 --> 00:00:41,950 So this main activity actually inherits all of the features and behaviors that are in sight of this 13 00:00:42,140 --> 00:00:43,660 composite activity. 14 00:00:43,680 --> 00:00:49,290 So if we just hold the common key and then press on this class here and if you are using a Windows machine 15 00:00:49,290 --> 00:00:52,690 you need to hold the control key and then press on. 16 00:00:52,710 --> 00:00:55,650 These are compact activity here. 17 00:00:55,650 --> 00:00:56,480 OK. 18 00:00:56,580 --> 00:01:02,190 So as you can see here this is our app computer activity and this computer activity as you can see there 19 00:01:02,190 --> 00:01:06,140 are lots of misfits here inside of this class and here. 20 00:01:06,540 --> 00:01:13,170 This class actually inherits all of the features and behaviors that are inside of this fragment activity. 21 00:01:13,170 --> 00:01:19,800 So this class extends this fragmented activity and there is an ease our relationship between these two 22 00:01:19,800 --> 00:01:24,310 classes and computer activity is up fragment activity. 23 00:01:24,330 --> 00:01:24,930 OK. 24 00:01:25,110 --> 00:01:30,720 And if I hold the command key and then press on this a fragment activity as you can see this is our 25 00:01:30,720 --> 00:01:36,620 fragment activity and this class extends the base fragment activity honeycombs. 26 00:01:36,660 --> 00:01:44,010 So there is an is a relationship between these two classes or cases of fragment activity and this base 27 00:01:44,010 --> 00:01:45,860 fragment activity honeycomb. 28 00:01:45,980 --> 00:01:46,570 OK. 29 00:01:46,890 --> 00:01:52,740 So if it actually holds the command key and then present this class here the base fragment activity 30 00:01:52,740 --> 00:01:59,750 honeycomb as you can see it says this based fragment activity actually extends base fragment activity 31 00:01:59,850 --> 00:02:00,500 do not. 32 00:02:00,680 --> 00:02:01,230 OK. 33 00:02:01,560 --> 00:02:08,370 So this class actually is actually up base like a base fragment activity or not. 34 00:02:08,430 --> 00:02:11,380 So there is an is a relationship between these two classes. 35 00:02:11,640 --> 00:02:17,550 So if I hold the command key and then press on this class as you can see here it says this base fragment 36 00:02:17,580 --> 00:02:21,180 activity not actually extends activity. 37 00:02:21,180 --> 00:02:24,600 So there is an is a relationship between these two classes. 38 00:02:24,720 --> 00:02:25,020 OK. 39 00:02:25,070 --> 00:02:30,200 And this class inherits all of the features and behaviors that are inside of this activity class. 40 00:02:30,210 --> 00:02:36,330 So if I hold the command key and then press on this activity class as you can see it says this activity 41 00:02:36,330 --> 00:02:40,370 class actually extends this context from lapper. 42 00:02:40,420 --> 00:02:49,250 OK so now as you can see here inside of this main activity if I just say that main activity extends 43 00:02:49,260 --> 00:02:55,380 and combat activity you can see that this class is going to actually inherit lots of methods from all 44 00:02:55,380 --> 00:03:01,710 of these classes are complete activity fragment activity based flagmen activity honeycomb based fragment 45 00:03:01,710 --> 00:03:04,080 activity not and this activity class. 46 00:03:04,120 --> 00:03:10,270 Ok so are these really important because in order to create an activity in our project. 47 00:03:10,280 --> 00:03:10,840 OK. 48 00:03:11,100 --> 00:03:18,510 In order to create an activity in our project in order to show the user some of outputs on the screen 49 00:03:18,960 --> 00:03:21,180 we need to actually create an activity. 50 00:03:21,180 --> 00:03:26,160 And here we need to actually extend from this app compact activity. 51 00:03:26,170 --> 00:03:26,540 OK. 52 00:03:26,550 --> 00:03:31,960 And as you can see this is our uncreate Smurfette and we are actually inheriting the Smurfette from 53 00:03:31,960 --> 00:03:33,270 base and compare activity. 54 00:03:33,270 --> 00:03:33,690 OK. 55 00:03:33,780 --> 00:03:34,600 Uncreate. 56 00:03:34,740 --> 00:03:37,200 And as you can see here it says at sign over. 57 00:03:37,200 --> 00:03:37,610 Right. 58 00:03:37,620 --> 00:03:39,260 So we are overwriting this memory. 59 00:03:39,270 --> 00:03:39,880 OK. 60 00:03:40,200 --> 00:03:42,710 And inside of this Mefford here it says super. 61 00:03:42,780 --> 00:03:45,240 So super refers to the superclass. 62 00:03:45,240 --> 00:03:45,960 OK superb. 63 00:03:45,960 --> 00:03:47,020 That uncreate. 64 00:03:47,070 --> 00:03:52,770 So here it's going actually are called the uncreate Meffert of the superclass here as you can see. 65 00:03:52,830 --> 00:03:55,850 Initialize the uncreate effect of the superclass. 66 00:03:55,980 --> 00:03:56,580 OK. 67 00:03:56,810 --> 00:04:02,950 Superdad and create Mefford and inside of the Prentice's as you can see it says saved instance state. 68 00:04:03,120 --> 00:04:04,830 OK this is our bundle OK. 69 00:04:04,940 --> 00:04:08,170 This is actually this object is actually of type A bundle. 70 00:04:08,340 --> 00:04:09,080 OK. 71 00:04:09,510 --> 00:04:13,330 And you don't need to know about this Bondel class. 72 00:04:13,400 --> 00:04:19,450 OK but for now you just know that this is our bundle and this is an object of this one. 73 00:04:19,470 --> 00:04:20,350 And here we are. 74 00:04:20,430 --> 00:04:22,260 This is actually a parameter. 75 00:04:22,260 --> 00:04:26,160 And here we are passing these parameters through the uncreate method of the superclass. 76 00:04:26,160 --> 00:04:32,070 So if I hold the command key and go inside of this app compact activity here as you can see there is 77 00:04:32,100 --> 00:04:34,630 actually an uncreate Mfat here again. 78 00:04:34,680 --> 00:04:37,880 So this class actually is overwriting this method. 79 00:04:38,070 --> 00:04:44,640 So and here as you can see it says uncreate And yet as you can see it has an ad site nullable Bondel 80 00:04:44,700 --> 00:04:46,230 save instant state. 81 00:04:46,260 --> 00:04:51,010 So at this moment as she exits an argument of type bundle and it is actually the nullable. 82 00:04:51,220 --> 00:04:51,950 OK. 83 00:04:52,350 --> 00:04:55,140 And here you can see these implementation's inside of this method. 84 00:04:55,170 --> 00:04:55,930 OK. 85 00:04:56,340 --> 00:05:02,080 But these are not are important and you don't need to know about these implementations but inside of 86 00:05:02,110 --> 00:05:08,380 this main activity that job I find here we need to actually call the uncreate Meffert of the superclass. 87 00:05:08,380 --> 00:05:13,540 We need to actually initialize the uncreate of the super of the superclass before we can actually call 88 00:05:13,600 --> 00:05:15,080 the set content view here. 89 00:05:15,100 --> 00:05:21,120 OK so it's content view are that lay out that activity underline main. 90 00:05:21,150 --> 00:05:21,560 OK. 91 00:05:21,730 --> 00:05:26,490 So some of it is going to actually call this set content view here as you can see here. 92 00:05:26,560 --> 00:05:30,580 And this is a method that you actually inherit from the activity class. 93 00:05:30,740 --> 00:05:31,200 OK. 94 00:05:31,330 --> 00:05:34,820 And this is going to actually show the user activity main. 95 00:05:34,960 --> 00:05:38,550 So this is our activity in that example. 96 00:05:38,920 --> 00:05:40,300 Okay. 97 00:05:40,360 --> 00:05:44,820 And then here as you can see it actually created an object from this toolbar class. 98 00:05:44,860 --> 00:05:45,770 Ok toolbar. 99 00:05:45,780 --> 00:05:52,540 And here it is actually initializing this object find view by ID or that Id dot toolbar set support 100 00:05:52,570 --> 00:05:53,830 action bar tool bar. 101 00:05:53,830 --> 00:05:58,020 So it's going to actually create a toolbar in our application. 102 00:05:58,330 --> 00:06:03,120 OK so now let's let me actually comment out these two lines of code here. 103 00:06:03,160 --> 00:06:06,910 So here let's actually run our project and see what happens. 104 00:06:06,910 --> 00:06:11,110 So as you can see here our application is running on this emulator here. 105 00:06:11,260 --> 00:06:13,420 And as you can see there is no toolbar here. 106 00:06:13,570 --> 00:06:14,170 OK. 107 00:06:14,410 --> 00:06:20,320 And if I go back and say this main activity double file here again and if I uncomment these two lines 108 00:06:20,320 --> 00:06:21,180 of code here. 109 00:06:21,340 --> 00:06:22,140 OK. 110 00:06:22,510 --> 00:06:24,580 As you can see here now as soon as an error. 111 00:06:24,580 --> 00:06:25,280 OK. 112 00:06:25,480 --> 00:06:30,720 Because of we didn't actually import the toolbar class into this class here. 113 00:06:30,820 --> 00:06:35,050 So here I just need to delete this toolbar here and then type it again here. 114 00:06:35,050 --> 00:06:36,290 OK toolbar. 115 00:06:36,970 --> 00:06:42,120 OK so now the toolbar class is actually automatically imported into this class here. 116 00:06:42,190 --> 00:06:42,540 OK. 117 00:06:42,550 --> 00:06:45,430 So let's actually run our project again and see what happens. 118 00:06:45,430 --> 00:06:51,070 So as you can see here our application is running again here on the simulator and you can see this toolbar 119 00:06:51,100 --> 00:06:53,090 here OK at 50. 120 00:06:53,290 --> 00:06:55,590 So hopefully that makes sense. 121 00:06:55,580 --> 00:07:00,760 And now let's actually go back and say this main activity that our fight here again and here I want 122 00:07:00,760 --> 00:07:06,640 to actually make the Spartan this PTEN second activity button a listener to the clicks that the user 123 00:07:06,640 --> 00:07:09,700 make on the button inside of this screen here. 124 00:07:09,700 --> 00:07:10,220 OK. 125 00:07:10,480 --> 00:07:12,900 So as you can see here I made a mistake here. 126 00:07:13,030 --> 00:07:15,910 And let's to go back and say this content underline that example. 127 00:07:15,910 --> 00:07:22,030 And here I need to click on this a clear cashier and here as you can see for the text of this button 128 00:07:22,510 --> 00:07:27,470 I just need to delete this letter T here and then press enter key on your keyboard. 129 00:07:27,490 --> 00:07:28,200 OK. 130 00:07:28,690 --> 00:07:32,970 So let's go back inside this our main activity that will fight here let's actually close this. 131 00:07:33,010 --> 00:07:35,470 I've compiled activity out of a file. 132 00:07:35,470 --> 00:07:39,410 Now I want to make the spot in listeners to the clicks that they use and make on the spot. 133 00:07:39,430 --> 00:07:40,050 OK. 134 00:07:40,150 --> 00:07:47,120 So here I just need to type in between such an activity that sits on click listener. 135 00:07:47,400 --> 00:07:47,910 OK. 136 00:07:49,190 --> 00:07:53,050 So unclick listener is actually an interface in Java. 137 00:07:53,210 --> 00:07:59,300 OK so here inside Apprentice's I need to actually specify the activity that this listener is belong 138 00:07:59,300 --> 00:07:59,580 to. 139 00:07:59,600 --> 00:08:00,290 OK. 140 00:08:00,470 --> 00:08:05,200 So first of all let me actually hear implement did unclick listener interface. 141 00:08:05,210 --> 00:08:09,350 So here I just need to implement implement view. 142 00:08:09,950 --> 00:08:13,940 That's unclick listener. 143 00:08:14,510 --> 00:08:16,750 So as you can see here this is actually an interface. 144 00:08:16,760 --> 00:08:20,320 Ok if you look at unclick and it is an interface in Java. 145 00:08:20,630 --> 00:08:26,420 And as you can see it is showing us an error and it says class main activity must either be declared 146 00:08:26,450 --> 00:08:31,440 abstract or implement implement abstract Smurfette unclick. 147 00:08:31,610 --> 00:08:33,690 As you can see here in unclick listener. 148 00:08:34,090 --> 00:08:34,570 OK. 149 00:08:34,910 --> 00:08:36,770 So this is actually an interface. 150 00:08:36,770 --> 00:08:43,580 And as you know are about interfaces in Java that are abstract methods in interfaces and in an interface. 151 00:08:43,580 --> 00:08:51,500 And we need to actually add every class that implements that interface need to actually implement the 152 00:08:51,500 --> 00:08:54,080 inherited method from that interface. 153 00:08:54,100 --> 00:09:00,650 Ok so here if we need to actually implement that inherited method that is inside of this unclick listener 154 00:09:00,860 --> 00:09:01,750 interface. 155 00:09:01,760 --> 00:09:07,780 So after this uncreate method let's actually type in here and click OK. 156 00:09:07,790 --> 00:09:12,730 So as you can see here this is the inherited Meffert from this article it's an interface. 157 00:09:12,770 --> 00:09:15,350 And if I press Enter key on my keyboard. 158 00:09:15,740 --> 00:09:17,340 Now you can see the Smurfette here. 159 00:09:17,360 --> 00:09:17,770 OK. 160 00:09:17,840 --> 00:09:21,560 Sign over right public Voyt and click it. 161 00:09:21,590 --> 00:09:22,210 OK. 162 00:09:22,520 --> 00:09:28,240 And this is if it actually exits an argument of type view and the name of this argument is the OK we 163 00:09:28,250 --> 00:09:32,940 can actually change the name of this argument to another value for example view. 164 00:09:33,200 --> 00:09:33,840 OK. 165 00:09:34,190 --> 00:09:40,310 And every court that we actually put in here is going to happen after we actually click on this. 166 00:09:40,310 --> 00:09:42,480 Let's go to say second activity button here. 167 00:09:42,590 --> 00:09:43,200 OK. 168 00:09:44,080 --> 00:09:51,070 So now inside Apprentice's I need to specify the activity the class that this listener actually belongs 169 00:09:51,070 --> 00:09:51,250 to. 170 00:09:51,250 --> 00:09:51,650 OK. 171 00:09:51,730 --> 00:09:57,410 So here we are making this between second activity a listener to the clicks that the user makes. 172 00:09:57,470 --> 00:09:58,670 OK on this button. 173 00:09:58,690 --> 00:09:59,210 OK. 174 00:09:59,410 --> 00:10:02,780 So here I need to specify the activity so I can just type in this. 175 00:10:03,070 --> 00:10:05,100 So this refers to this class. 176 00:10:05,230 --> 00:10:05,690 OK.