1 00:00:01,020 --> 00:00:03,320 Hello this is or Corti. 2 00:00:03,480 --> 00:00:10,110 And in this material we are going to create some instance variables and an inner insight or calculator 3 00:00:10,110 --> 00:00:11,580 class. 4 00:00:11,580 --> 00:00:18,250 So first let's create and you know inside this calculator class I'm going to type in private ENM. 5 00:00:18,440 --> 00:00:23,780 So you already know that Iran is actually creating our own type. 6 00:00:23,870 --> 00:00:29,380 For example we have the type integer we have we have a type text view or Potten. 7 00:00:29,390 --> 00:00:34,780 But when you create an arena it means that we want to create our own custom type. 8 00:00:35,090 --> 00:00:35,710 Right. 9 00:00:35,720 --> 00:00:41,720 So I'm going to say probates in am and I can say name it as operator. 10 00:00:41,810 --> 00:00:46,180 So I'm going to just make it capitalized. 11 00:00:46,210 --> 00:00:46,900 Operator 12 00:00:52,070 --> 00:00:56,750 And then I'm going to open and close this in and by using these curly braces so I'm going to provide 13 00:00:56,870 --> 00:01:02,660 some values here for my you know the first one is going to be selected sruti emulator. 14 00:01:02,660 --> 00:01:13,420 We have this up plus OPERATOR So I'm going to say plus comma we have this subtraction operator subtract 15 00:01:14,500 --> 00:01:25,170 comma if we have multiply operators of multiply comma and finally we have this divide operator divide 16 00:01:28,120 --> 00:01:34,390 and we also have this equal operator so equal. 17 00:01:34,480 --> 00:01:36,320 So these are the values of our in our. 18 00:01:36,340 --> 00:01:37,900 OPERATOR OK. 19 00:01:38,170 --> 00:01:42,580 Now after this Inam I'm going to create some instance variables. 20 00:01:42,580 --> 00:01:49,540 So here at the bottom here after these two takes you I'm going to create a comment here. 21 00:01:50,410 --> 00:01:54,590 Instance variables instance of 22 00:01:57,690 --> 00:02:07,400 so the first instance variable is going to be off tapes 3 and so private Stream current number and number 23 00:02:07,400 --> 00:02:08,660 semicolon. 24 00:02:09,190 --> 00:02:13,050 So let's create another instance of our evil private Stream. 25 00:02:13,390 --> 00:02:22,570 And the name is going to be stream number at left semicolon and another instance variable private strange 26 00:02:23,770 --> 00:02:30,700 strange number at right semicolon. 27 00:02:30,930 --> 00:02:34,760 So what does this mean string number had left string number at right. 28 00:02:34,770 --> 00:02:37,140 Let me show you the emulator. 29 00:02:37,560 --> 00:02:43,380 So here for example we have their current number so I can actually have this number two. 30 00:02:43,380 --> 00:02:44,940 This is going to be the current number. 31 00:02:44,970 --> 00:02:45,630 Right. 32 00:02:46,020 --> 00:02:51,680 And we created a variable or instance variable named as string number at left. 33 00:02:51,690 --> 00:02:54,540 This means at the left side of the operator. 34 00:02:54,540 --> 00:02:59,600 So when I say multiply it here as you can see we have to multiply. 35 00:02:59,610 --> 00:03:04,020 So now the number two is at the left side of this operator. 36 00:03:04,020 --> 00:03:06,440 So this is called string number left. 37 00:03:06,720 --> 00:03:13,050 And then actually select another number for example Number Six Here is number 6 is going to be district 38 00:03:13,050 --> 00:03:13,570 number. 39 00:03:13,660 --> 00:03:14,380 Right. 40 00:03:14,460 --> 00:03:17,780 The number at the right of the operator OK. 41 00:03:17,910 --> 00:03:20,710 So to multiply by six. 42 00:03:20,820 --> 00:03:25,480 Now when I press on equal what the result is going to be shown to the user. 43 00:03:25,530 --> 00:03:31,700 So that's why we created the card number this three number at lift and the string number at right. 44 00:03:31,850 --> 00:03:32,420 OK. 45 00:03:34,200 --> 00:03:38,160 Let's also create an instance variable of our own type. 46 00:03:38,380 --> 00:03:42,690 So private's and the name is going to be operator. 47 00:03:42,840 --> 00:03:43,520 Operator 48 00:03:46,750 --> 00:03:54,120 And there is another actually make mateys a type operator capitalized. 49 00:03:54,340 --> 00:03:58,220 Is that I just want to make it more special. 50 00:03:58,450 --> 00:04:05,140 OK because this is actually our own type if you want to you can just make this method only the first 51 00:04:05,140 --> 00:04:10,570 letter capitalized and then the other letters to be lowercase. 52 00:04:10,720 --> 00:04:15,240 But here I just wanted to make it more special because this is going to be the operator. 53 00:04:15,250 --> 00:04:18,370 This is very important in our church related application. 54 00:04:18,640 --> 00:04:22,280 So the type is operator and the name is going to be current. 55 00:04:22,680 --> 00:04:31,780 Operator syndicalism let's also create an instance variable of that integer. 56 00:04:31,840 --> 00:04:35,270 So private int and the name is going to be calculations 57 00:04:37,990 --> 00:04:40,720 resolved semi-aquatic 58 00:04:43,610 --> 00:04:49,220 now I am going to actually paste a method inside our calculator class. 59 00:04:49,250 --> 00:04:53,010 This is going to be named as number is tapped. 60 00:04:53,030 --> 00:04:54,470 So let me show you the emulator. 61 00:04:54,530 --> 00:05:00,200 So whenever I let me click click on clear but never to use it actually taps on this button for example 62 00:05:00,200 --> 00:05:07,790 Number 8 or number 9 you can see that the numbers are actually put beside each other number 5 free to 63 00:05:07,910 --> 00:05:09,150 1. 64 00:05:09,240 --> 00:05:12,780 This is going to be called the method that we're into right now. 65 00:05:13,010 --> 00:05:18,340 So let's go inside this calculator class before the end in brace of this chapter a little class. 66 00:05:18,380 --> 00:05:19,380 I'm going to paste this. 67 00:05:19,450 --> 00:05:25,050 So here it is some of it private void number is tapped. 68 00:05:25,100 --> 00:05:30,100 This method has a parameter that is of type integer and its name is tapped number. 69 00:05:30,110 --> 00:05:35,240 So whenever the if you want to actually call the Smurfette we're going to also pass that number that 70 00:05:35,240 --> 00:05:37,210 is tapped to this method. 71 00:05:37,280 --> 00:05:41,980 So the name of the parameter is papped number inside the Smurfette. 72 00:05:42,200 --> 00:05:47,200 We are going to actually initialize our variable current number. 73 00:05:47,410 --> 00:05:47,900 OK. 74 00:05:48,230 --> 00:05:58,490 So it is a current number assignment operator current number plus strange that value of tapped numbers 75 00:05:58,490 --> 00:06:00,040 so we want to actually. 76 00:06:00,080 --> 00:06:07,220 In other words we want to concatenate the current number that is tapped with the value that is a path 77 00:06:07,280 --> 00:06:07,760 again. 78 00:06:07,760 --> 00:06:12,230 So for example the emulator for example of we have number one that is tapped. 79 00:06:12,260 --> 00:06:13,070 Right. 80 00:06:13,100 --> 00:06:19,130 And when they use that actually again taps on this number five we can see that number one is concatenated 81 00:06:19,130 --> 00:06:24,540 with the value number five the current number plus strange that value of. 82 00:06:24,540 --> 00:06:32,300 So it is the string that value of is going to get the integer value and convert it to a string value 83 00:06:32,480 --> 00:06:33,890 because we want to show it here. 84 00:06:34,100 --> 00:06:39,800 So string to the value of tap number and then if you want to actually display this value on the screen 85 00:06:39,800 --> 00:06:45,030 so we don't really want to say 60 results that said text current number. 86 00:06:45,050 --> 00:06:48,240 So that's why you can see this value here. 87 00:06:48,230 --> 00:06:59,930 Now let's go inside our uncreate method here first and after this set content you Meffert we are going 88 00:06:59,930 --> 00:07:08,000 to initialize the current number variable here because as soon as the application runs the current number 89 00:07:08,000 --> 00:07:09,810 variable is not initialized. 90 00:07:09,980 --> 00:07:11,700 So an added value is not. 91 00:07:11,720 --> 00:07:16,040 So if you're going to say current number assignment operator two coats. 92 00:07:16,070 --> 00:07:20,860 So it just isn't an empty string value to discard it's number variable. 93 00:07:21,020 --> 00:07:28,690 And for this call collations result we're going to also assign an initial value as zero. 94 00:07:28,850 --> 00:07:35,840 So we call a display event the app runs these two variables is the value of these two variables is not 95 00:07:35,840 --> 00:07:40,420 actually null the already initialized a default value. 96 00:07:40,450 --> 00:07:42,860 This is valuable here. 97 00:07:42,860 --> 00:07:43,570 So that's it. 98 00:07:43,580 --> 00:07:52,270 Now we are going to actually call DMF that number is tapped from some of our case statements inside 99 00:07:52,280 --> 00:07:54,300 this unclick method. 100 00:07:54,630 --> 00:07:58,940 So the name of the method is number is that. 101 00:07:58,940 --> 00:08:02,630 So this means that we need to call this method whenever. 102 00:08:02,690 --> 00:08:07,470 Let me show the emulator Let me show you on that whenever a number is tapped. 103 00:08:07,490 --> 00:08:07,850 Right. 104 00:08:07,870 --> 00:08:11,770 Whenever number is that you're going to call number is tapped. 105 00:08:11,810 --> 00:08:14,450 So we have a pretty servant here right. 106 00:08:14,450 --> 00:08:16,680 Case are that are you that petty and separate. 107 00:08:16,760 --> 00:08:19,300 So we're going to say that number is tapped. 108 00:08:19,580 --> 00:08:24,050 The user actually has to have on the number seven so we're going to pass numbers seven to the Smurfette 109 00:08:24,380 --> 00:08:26,060 tapped number number 7. 110 00:08:26,360 --> 00:08:31,310 So we have BT and a second number is tapped number eight. 111 00:08:31,410 --> 00:08:35,070 Number nine number is tapped 9. 112 00:08:35,550 --> 00:08:40,970 So if you want to you can skip this part of the video but I'm going to type it here manually nobody 113 00:08:41,050 --> 00:08:41,820 tapped. 114 00:08:42,140 --> 00:08:42,840 Number four 115 00:08:45,500 --> 00:09:10,050 number five numbers theft five. 116 00:09:10,200 --> 00:09:11,960 And finally we have numbers zero. 117 00:09:12,180 --> 00:09:13,260 Nobody is tapped. 118 00:09:13,260 --> 00:09:14,270 Numbers zero. 119 00:09:14,450 --> 00:09:23,150 OK so now let's let me scroll down here so you can see that we call it the results. 120 00:09:23,190 --> 00:09:26,580 That set takes the current number so you want to display its value on the screen. 121 00:09:26,760 --> 00:09:29,850 Let's run the app and let's see what happens. 122 00:09:29,880 --> 00:09:32,330 Let me show you the emulator. 123 00:09:32,420 --> 00:09:34,950 So now our app is running on the simulator. 124 00:09:35,090 --> 00:09:37,340 Let's click on number four. 125 00:09:37,400 --> 00:09:49,450 So here you can see Number four is displayed here number 5 6 2 3 0 9 8 7 again 4 1. 126 00:09:49,670 --> 00:09:51,720 So everything works fine here. 127 00:09:52,040 --> 00:09:52,590 OK. 128 00:09:52,730 --> 00:09:59,870 So let's go back to our studio now of we need to create another method that is going to handle it when 129 00:09:59,870 --> 00:10:06,440 we use it actually taps on the operator for example plus a D minus operator the multiplication operator 130 00:10:06,730 --> 00:10:08,160 the device operator. 131 00:10:08,240 --> 00:10:13,370 So I think that's enough for the situation and it's really really going to create another benefit to 132 00:10:13,370 --> 00:10:16,950 handle the tapping and the operator. 133 00:10:17,090 --> 00:10:21,860 Thank you very much for watching and I look forward to seeing you in the next tutorial.