1 00:00:00,450 --> 00:00:06,950 So now let's actually scroll to the top here and here inside our main activity class. 2 00:00:07,020 --> 00:00:09,990 I'm going to actually declare and other three invaluable. 3 00:00:09,990 --> 00:00:18,720 So here just type in strange and here the name of this string value but is a computer or you can say 4 00:00:18,720 --> 00:00:21,990 unique computer ID. 5 00:00:22,320 --> 00:00:22,800 OK. 6 00:00:22,890 --> 00:00:24,670 You need computer 80. 7 00:00:24,810 --> 00:00:30,540 So as you can see inside our class main activity class we created the bell which is of pipes. 8 00:00:30,870 --> 00:00:34,580 And the name of this variable is unique computer ID. 9 00:00:34,590 --> 00:00:37,810 So now let's actually scroll down here. 10 00:00:38,040 --> 00:00:44,660 So let's actually go after the Indian curly brace of the Smurfette of this uncreate method. 11 00:00:44,880 --> 00:00:46,250 And inside this class. 12 00:00:46,260 --> 00:00:52,220 So as you can see here this is the ending curly brace of this class and here this is the ending calibers 13 00:00:52,230 --> 00:00:53,630 of this uncreate method. 14 00:00:53,640 --> 00:01:00,240 So before the end of this class and inside this class inside the curly braces of this class I'm going 15 00:01:00,240 --> 00:01:07,030 to actually paste in some lines of code here and then I'm going to explain to you what's going on here. 16 00:01:07,080 --> 00:01:11,670 So as you can see here these are the lines of code that I pasted here. 17 00:01:11,910 --> 00:01:16,280 So we have a method and the access modifier of the Smurfette is private. 18 00:01:16,290 --> 00:01:19,010 The return type of this method is void. 19 00:01:19,050 --> 00:01:23,820 So as you can see here when I say that the axis modifier of this method is private I mean that this 20 00:01:23,820 --> 00:01:26,730 method is only accessible inside this class. 21 00:01:26,730 --> 00:01:29,950 So you already know about access modifiers in Java. 22 00:01:30,300 --> 00:01:35,270 And here we say that the return type of the term type of this method is void and dismissed. 23 00:01:35,340 --> 00:01:37,080 This means that this method is going to return. 24 00:01:37,080 --> 00:01:39,480 Nothing is going to just do something right. 25 00:01:39,550 --> 00:01:41,580 It's not going to return anything. 26 00:01:41,820 --> 00:01:42,400 OK. 27 00:01:42,870 --> 00:01:49,970 And then the name of this method is produce a new computer and put it in the database. 28 00:01:50,010 --> 00:01:56,250 So the job of this method is to create a new computer object and to put it into the database in the 29 00:01:56,280 --> 00:01:58,640 server right on the server. 30 00:01:58,710 --> 00:02:03,140 So as you can see here this method actually accepts some arguments. 31 00:02:03,510 --> 00:02:10,720 The first argument as you can see here is of type string and the name of this argument is computer name. 32 00:02:10,740 --> 00:02:16,070 The second argument of this method is actually the computer power which is of type integer. 33 00:02:16,110 --> 00:02:22,350 The first argument of this method is actually computer speed which is again of type integer. 34 00:02:22,410 --> 00:02:27,930 The fourth argument of this method is actually computer RAM which is of integer. 35 00:02:28,200 --> 00:02:31,640 And here we have computer screen which is of type string. 36 00:02:32,010 --> 00:02:38,630 And we have computer keyboard which is a unit of papes trained and we have computer CPQ which is after 37 00:02:38,660 --> 00:02:39,580 high street. 38 00:02:39,870 --> 00:02:45,000 So now let's actually go inside the curly braces off the Smurfette And let's see what's going on here 39 00:02:45,750 --> 00:02:52,050 inside the Smurfit as you can see we have this statement and this statement here is saying that text 40 00:02:52,080 --> 00:03:00,570 U-2s so the text utility is actually a class in Java that we are going to use in order to actually do 41 00:03:00,630 --> 00:03:02,720 something with our texts. 42 00:03:02,810 --> 00:03:10,650 So the utility class is going to actually give us some methods in order to actually do something in 43 00:03:10,650 --> 00:03:16,840 order to check whether for example this unique computer ID variable is empty or not. 44 00:03:17,130 --> 00:03:23,160 So we can use this class in order to check this here in order to check that with this unique computer 45 00:03:23,160 --> 00:03:28,800 ID variable which we created inside this class inside me and like if the glass is empty or not. 46 00:03:28,830 --> 00:03:30,350 So now let me scroll to the top here. 47 00:03:30,360 --> 00:03:36,900 As you can see inside this class we created we actually declared this variable which is of types 3 in 48 00:03:36,990 --> 00:03:40,050 unique computer ID and we didn't initialize it yet. 49 00:03:40,080 --> 00:03:40,760 Right. 50 00:03:40,760 --> 00:03:46,830 And now as you can see here inside the Smurfette inside this method you use on your computer and put 51 00:03:46,830 --> 00:03:47,850 it in the database. 52 00:03:47,970 --> 00:03:50,720 Is it saying that it takes you to use that is empty. 53 00:03:50,820 --> 00:03:53,810 So this class takes you to is going to check by this. 54 00:03:53,830 --> 00:03:59,430 But by using this method it's going to check that whether this unique computer ID is valuable is empty 55 00:03:59,430 --> 00:04:00,210 or not. 56 00:04:00,210 --> 00:04:00,660 Right. 57 00:04:00,930 --> 00:04:08,130 And if this expression evaluates to TRUE this means that if the value of this unique computer ID valuable 58 00:04:08,180 --> 00:04:13,590 is actually empty right then it's going to go inside the curly braces of this method and it's going 59 00:04:13,590 --> 00:04:19,710 to execute this line of what here is going to actually assign a value to this unique computer ID so 60 00:04:19,740 --> 00:04:27,720 unique computer ID assignment operator and we are actually referencing our database so you already know 61 00:04:27,840 --> 00:04:34,140 that this database reference valuable is actually holding a reference to the computers category into 62 00:04:34,140 --> 00:04:35,540 the database. 63 00:04:35,670 --> 00:04:36,370 Right. 64 00:04:36,450 --> 00:04:42,190 So you need computer ID assignment operator database or friends that push. 65 00:04:42,330 --> 00:04:47,820 So you know that when I call to push my faith here on our reference it's going to actually create a 66 00:04:47,820 --> 00:04:49,750 unique ID. 67 00:04:49,800 --> 00:04:50,390 Right. 68 00:04:50,640 --> 00:04:56,070 So when you call the push method on your reference it's going to create a unique key or unique a unique 69 00:04:56,100 --> 00:04:59,930 ID for or actually reference. 70 00:04:59,960 --> 00:05:06,200 Here we are calling this method get ciii an undisputed truth can actually get that value that that unique 71 00:05:06,410 --> 00:05:13,070 random ID is going to get that key and it's going to assign that key to this unique computer ID so that 72 00:05:13,070 --> 00:05:14,580 she is going to be off the street. 73 00:05:14,600 --> 00:05:15,160 Right. 74 00:05:15,200 --> 00:05:20,460 Which is actually an object so we can assign it to this unique computer ID which is off the street. 75 00:05:20,630 --> 00:05:21,620 Right. 76 00:05:21,770 --> 00:05:28,770 And now as you can see here we have these lines of code here in line number one hundred and sixty two. 77 00:05:29,090 --> 00:05:33,290 We have created an object of type computer class. 78 00:05:33,590 --> 00:05:39,020 So if we actually go inside this computer class here you can see that we have these instance variables 79 00:05:39,380 --> 00:05:45,890 computer name computer power computer speed computer ram computer screen computer keyboard and computer 80 00:05:45,890 --> 00:05:46,450 CPQ. 81 00:05:46,460 --> 00:05:48,950 These are the instant Swabia bells of this computer. 82 00:05:48,950 --> 00:05:49,530 Right. 83 00:05:49,850 --> 00:05:57,650 And we have these empty constructor which we needed which it is important that we actually put this 84 00:05:57,650 --> 00:05:59,770 into a constructor here. 85 00:06:00,140 --> 00:06:06,210 And we also have this constructor that is going to initialize our instance variables. 86 00:06:06,320 --> 00:06:07,370 Right. 87 00:06:07,370 --> 00:06:15,430 So you know about these kinds of constructors in Java and as you can see here we have these methods 88 00:06:15,470 --> 00:06:20,510 or these getters in order to actually get the values of our instance variables. 89 00:06:20,510 --> 00:06:24,460 So for example computers will compute return computer CPQ. 90 00:06:24,590 --> 00:06:25,670 Right. 91 00:06:25,670 --> 00:06:32,140 So inside is main activity that Java class as you can see here here here inline number of 162. 92 00:06:32,180 --> 00:06:38,000 We created an object OFF-SIDE computer assignment operator new computer. 93 00:06:38,000 --> 00:06:42,840 So as you can see here we are actually creating a new instance of type computer class. 94 00:06:43,160 --> 00:06:48,850 And here we are going to assign that instance to this computer invaluable right. 95 00:06:48,880 --> 00:06:50,360 This is actually a about right. 96 00:06:50,390 --> 00:06:57,020 And here after the assignment operator here you are creating an instance of type computer class and 97 00:06:57,020 --> 00:06:59,780 then we can actually be assigned this instance to this variable. 98 00:06:59,780 --> 00:07:05,120 So whenever that you want to actually ferde to this instance I can just refer to this name here to the 99 00:07:05,120 --> 00:07:06,460 name of this value. 100 00:07:07,250 --> 00:07:12,080 So again computer computer assignment operator new computer. 101 00:07:12,200 --> 00:07:17,420 And here we are using that constructor that is going to initialize our instance variables. 102 00:07:17,450 --> 00:07:21,430 So as you can see here this method you use in your computer and put it in the database method. 103 00:07:21,440 --> 00:07:23,870 This method has some arguments right. 104 00:07:23,870 --> 00:07:28,450 So by using these arguments I can initialize this instance. 105 00:07:28,580 --> 00:07:34,010 So for the first argument I passed this computer name which is of types 3 and for the second argument 106 00:07:34,030 --> 00:07:36,960 I passed the computer power for the first argument. 107 00:07:37,010 --> 00:07:43,580 I passed the computer speed for the forth argument I passed the computer RAM and here I passed the computer 108 00:07:43,580 --> 00:07:47,110 screen computer keyboard and computer CPQ. 109 00:07:47,330 --> 00:07:54,300 So you have created an instance of type computer class by using these arguments of this method. 110 00:07:54,410 --> 00:07:55,370 Right. 111 00:07:55,430 --> 00:08:00,470 So then that I call this method and then I actually passed these values to this method is going to actually 112 00:08:00,470 --> 00:08:04,190 create a new instance of type computer class for us. 113 00:08:04,190 --> 00:08:05,250 Right. 114 00:08:05,360 --> 00:08:12,230 And here in line number one hundred sixty four as you can see I am referring to this database reference. 115 00:08:12,290 --> 00:08:12,980 Right. 116 00:08:12,980 --> 00:08:19,390 So this database reference has already a reference to the computers category. 117 00:08:19,400 --> 00:08:24,890 So if I actually scroll to the top here and go inside these uncreate Smurfit as you can see in line 118 00:08:24,890 --> 00:08:30,280 number 66 as you can see here we are actually creating a reference to the computers category. 119 00:08:30,280 --> 00:08:36,260 So that's why I said that these these databases are friends is what is holding a reference to these 120 00:08:36,260 --> 00:08:37,910 computers category. 121 00:08:37,970 --> 00:08:39,460 So let's scroll down here. 122 00:08:39,590 --> 00:08:43,900 So now I say database or France that child. 123 00:08:43,990 --> 00:08:52,160 And here I specifying the key right the name of this child the key unique computer ID as you can see 124 00:08:52,160 --> 00:08:52,990 here. 125 00:08:53,000 --> 00:09:00,390 So the key is this one right Junichi computer ID dot sits value. 126 00:09:00,530 --> 00:09:02,520 Computer. 127 00:09:02,640 --> 00:09:03,360 Right. 128 00:09:03,410 --> 00:09:08,710 So when I say sit around your computer as you can see here this is actually an object of type computer 129 00:09:08,720 --> 00:09:09,630 right. 130 00:09:09,680 --> 00:09:13,930 So this unique computer idea is going to be actually up. 131 00:09:14,240 --> 00:09:15,330 Category. 132 00:09:15,380 --> 00:09:15,800 Right. 133 00:09:15,800 --> 00:09:21,380 So we have actually a reference to the computers category and here as you can see here in line number 134 00:09:21,380 --> 00:09:29,870 one hundred and fifty eight we are creating a unique ID a unique ID that is randomly created and it 135 00:09:29,870 --> 00:09:35,090 is not going to be the same as any other ideas that are going to be created by the firebase. 136 00:09:35,090 --> 00:09:41,550 So when I say database reference that push is going to actually create a unique ID for me right dot 137 00:09:41,740 --> 00:09:47,870 get key is going to actually get that ID and is going to sign that ID to this unique computer ID which 138 00:09:47,870 --> 00:09:48,770 is of type string. 139 00:09:48,860 --> 00:09:55,640 So now this unique computer Id actually holds that unique ID that is created by the firebase then I 140 00:09:55,640 --> 00:09:58,440 call this push method is going to create that ID. 141 00:09:58,460 --> 00:10:00,240 And here we are getting that. 142 00:10:00,260 --> 00:10:07,240 And we are assigning that key to this unique computer ID in low number of 164 as you can see here I 143 00:10:07,240 --> 00:10:09,620 am saying that database reference. 144 00:10:09,950 --> 00:10:15,980 So this database reference is actually holding our reference to the computers category right. 145 00:10:16,340 --> 00:10:20,850 And here I am specifying the child of that can computers Kathakali. 146 00:10:20,990 --> 00:10:27,290 So the child of that can computers category is going to be unique computer ID right. 147 00:10:27,890 --> 00:10:34,070 So now we have our computers theoretically and the child of that computers category has this. 148 00:10:34,460 --> 00:10:36,870 She has this unique computer ID. 149 00:10:37,160 --> 00:10:40,770 And here we are saying sets value computer. 150 00:10:41,120 --> 00:10:47,780 So this means that is going to actually again treat this Junichi computer ID as a category because we 151 00:10:47,790 --> 00:10:49,480 are passing this object here. 152 00:10:49,490 --> 00:10:50,020 Right. 153 00:10:50,210 --> 00:10:55,930 So now let me actually to go inside the computer class as you can see here we have this instance variables 154 00:10:55,940 --> 00:10:56,300 right. 155 00:10:56,300 --> 00:11:02,150 For example computer name computer power computer speed computer ram computer screen computer keyboard 156 00:11:02,180 --> 00:11:03,690 and computer CPQ. 157 00:11:04,010 --> 00:11:10,820 So when I pass an object to our category here as you can see when I pass an object to our category for 158 00:11:10,820 --> 00:11:18,480 example this one unit computer ID is going to actually put that object with those names and values. 159 00:11:19,270 --> 00:11:21,790 Write is going to for example create a name. 160 00:11:21,910 --> 00:11:27,210 For example the name is computer name and the value and the value is going to be the value that we passed 161 00:11:27,210 --> 00:11:29,180 through this method to this method here. 162 00:11:29,200 --> 00:11:33,800 As you can see so now when we run a project I'll talk more about that later. 163 00:11:33,910 --> 00:11:38,860 And it will make sense but for now just know that we are saying that it is an offense that child the 164 00:11:38,860 --> 00:11:40,560 child is unique computer ID. 165 00:11:40,840 --> 00:11:44,440 And it's going to actually treat this unique computer ID as a category. 166 00:11:44,440 --> 00:11:45,120 Why. 167 00:11:45,280 --> 00:11:53,180 Because we are sitting on the computer object to this unique computer ID that object has keys and names. 168 00:11:53,440 --> 00:11:56,930 So now when I run my project you will see how this works. 169 00:11:57,460 --> 00:12:02,380 And here as you can see in line number of one hundred and sixty six we are calling and other them if 170 00:12:02,380 --> 00:12:06,060 it change the text of send or update button. 171 00:12:06,070 --> 00:12:08,000 According to the situation. 172 00:12:08,020 --> 00:12:10,570 So now let me show you the emulator here. 173 00:12:10,720 --> 00:12:15,030 As you can see let me just make this virtual keyboard disappear. 174 00:12:15,040 --> 00:12:20,830 So as you can see here we have this edit text and the user is supposed to actually enter some values 175 00:12:20,830 --> 00:12:26,660 here and when the user just click on this send button here it can actually send this data to the set 176 00:12:26,670 --> 00:12:26,820 right. 177 00:12:26,840 --> 00:12:27,610 Right. 178 00:12:27,940 --> 00:12:34,870 But after that I want to actually allow the user to update those data are right. 179 00:12:35,020 --> 00:12:40,270 And then when I want to actually update those data I can actually hear change the takes of this button 180 00:12:40,540 --> 00:12:42,000 to update data. 181 00:12:42,160 --> 00:12:45,450 So that's why I actually created this method here. 182 00:12:45,450 --> 00:12:48,490 I actually put this fit but we haven't still created this method. 183 00:12:48,670 --> 00:12:51,920 And that's why you can see that this method is actually in red. 184 00:12:52,060 --> 00:12:54,400 Change the text of sent or update button. 185 00:12:54,400 --> 00:12:55,940 According to the situation. 186 00:12:55,960 --> 00:13:01,780 So after the end in calibrates of the Smurfette Let's actually create the Smurfit here. 187 00:13:01,780 --> 00:13:08,530 Here I can say private and here I can say void and then I can actually first with the name of the Smurfette 188 00:13:08,770 --> 00:13:13,430 change the takes of send or update Potten according to the situation. 189 00:13:13,630 --> 00:13:18,370 And then I put a pair of parenthesis here and then I open and close this method by using these curly 190 00:13:18,370 --> 00:13:19,080 braces. 191 00:13:19,330 --> 00:13:21,750 And now as you can see here the error is gone right.