1 00:00:04,300 --> 00:00:08,300 Welcome back. In our duration's report activity, 2 00:00:08,300 --> 00:00:11,500 we've still got the delete menu option to implement. 3 00:00:12,200 --> 00:00:15,200 The first step is to show the DatePickerDialog. 4 00:00:43,860 --> 00:00:48,060 I'll use the light bulb to convert the dialog title to a string resource 5 00:00:48,060 --> 00:00:52,060 called date_title_delete. 6 00:01:03,160 --> 00:01:05,960 Deleting the rows is fairly straightforward. 7 00:01:06,260 --> 00:01:08,860 We just tell the content provider to delete 8 00:01:08,860 --> 00:01:11,360 all records earlier than a certain date. 9 00:01:12,350 --> 00:01:16,450 A slight complication is we want to get confirmation first. 10 00:01:17,250 --> 00:01:21,350 The user could potentially be deleting thousands of records. 11 00:01:21,750 --> 00:01:23,750 It's only fair to warn them first. 12 00:01:24,740 --> 00:01:28,540 What we'll do is respond to the date they choose in our 13 00:01:28,540 --> 00:01:30,440 OnDateSet function, 14 00:01:30,990 --> 00:01:35,490 that will use our AppDialog class to display the confirmation dialog, 15 00:01:35,990 --> 00:01:38,490 and we'll perform the deletion in the 16 00:01:38,490 --> 00:01:40,990 OnPositiveDialogResult function. 17 00:01:41,390 --> 00:01:43,990 Let's start with the OnDateSet function 18 00:01:43,990 --> 00:01:46,290 in our durations report activity. 19 00:01:49,290 --> 00:01:51,650 When OnDateSet's called, 20 00:01:51,650 --> 00:01:53,450 we're provided with the year, 21 00:01:53,450 --> 00:01:57,250 month and day that a user selected from the DatePicker. 22 00:01:58,140 --> 00:02:01,740 Rather than just go ahead and delete all the rows before that date, 23 00:02:02,140 --> 00:02:03,640 we'll pop up a dialog 24 00:02:03,640 --> 00:02:07,140 to let the user confirm that they really want to delete the rows. 25 00:02:08,039 --> 00:02:11,540 Displaying the dialog is easy, we've done it quite a few times now. 26 00:02:12,090 --> 00:02:15,290 A slight complication is that we should show the date 27 00:02:15,290 --> 00:02:17,090 in the user's preferred format. 28 00:02:17,890 --> 00:02:19,490 That should be easy, shouldn't it. 29 00:02:19,740 --> 00:02:23,740 We've already done something similar in the DurationsViewModel class. 30 00:02:24,620 --> 00:02:27,720 Unfortunately, the date format API 31 00:02:27,720 --> 00:02:31,620 doesn't provide a suitable function when we haven't got a date. 32 00:02:32,120 --> 00:02:35,620 We've got three values: the year, month and day. 33 00:02:36,280 --> 00:02:39,580 Before we can format that in a way that the user is familiar with, 34 00:02:39,940 --> 00:02:42,600 we need to convert those three values into a date. 35 00:02:53,100 --> 00:02:56,900 If you're prompted for the imports, the Gregorian calendar 36 00:02:56,900 --> 00:02:59,200 comes from java.util 37 00:02:59,560 --> 00:03:04,160 There is a Gregorian calendar class in android.icu.util, 38 00:03:04,710 --> 00:03:07,700 but that requires a minimum SDK of 24. 39 00:03:08,580 --> 00:03:11,680 Our app runs on all android versions back to 17, 40 00:03:11,680 --> 00:03:13,380 so we can't use that class. 41 00:03:20,280 --> 00:03:25,770 The date format class we want is in android.text.format. 42 00:03:29,370 --> 00:03:32,140 We create a new Gregorian calendar object 43 00:03:32,140 --> 00:03:35,240 and use that to convert our three values into a date. 44 00:03:35,790 --> 00:03:38,090 In this case, the time in milliseconds. 45 00:03:38,970 --> 00:03:42,750 That gives us something we can pass to date format's format function. 46 00:03:43,740 --> 00:03:46,540 Now we've got a string that makes sense to the user. 47 00:03:47,530 --> 00:03:50,330 All right. The remaining code 48 00:03:50,330 --> 00:03:52,590 sets up the arguments for our dialog. 49 00:04:05,890 --> 00:04:08,990 The light bulb doesn't give us the option to extract the message 50 00:04:08,990 --> 00:04:10,240 into a string resource. 51 00:04:10,790 --> 00:04:13,390 We have to edit strings.xml, 52 00:04:13,390 --> 00:04:15,090 and add the resource manually. 53 00:04:15,890 --> 00:04:20,290 Cut all the text inside the speech marks without the speech marks, 54 00:04:21,649 --> 00:04:24,150 then open strings.xml. 55 00:04:34,750 --> 00:04:36,740 I'll call the new resource 56 00:04:36,740 --> 00:04:40,340 delete_timings_message. 57 00:05:02,340 --> 00:05:04,540 We also need to change the placeholder. 58 00:05:05,200 --> 00:05:07,900 At the moment, it's using a Kotlin variable, 59 00:05:08,150 --> 00:05:10,280 and we need a resource placeholder. 60 00:05:19,530 --> 00:05:22,530 Back in our code, we'll use the resource ID. 61 00:05:47,630 --> 00:05:49,630 Next, we put the date value, 62 00:05:49,930 --> 00:05:53,920 the full date time in milliseconds into the args bundle. 63 00:05:54,470 --> 00:05:58,870 We're going to need that later when we react to the positive dialog button 64 00:05:59,120 --> 00:06:00,780 and perform the deletion. 65 00:06:12,580 --> 00:06:16,080 I've used a constant to store the value in the args bundle. 66 00:06:16,630 --> 00:06:19,930 We'll use the same constant to get the value back out again 67 00:06:20,290 --> 00:06:22,890 so I'd better declare it up at the start of the file. 68 00:06:42,890 --> 00:06:46,390 All right. If the user confirms the deletion, 69 00:06:46,390 --> 00:06:50,690 app dialog will call our on PositiveDialogResult function. 70 00:06:51,490 --> 00:06:54,990 I'll make the class implement the dialog events interface. 71 00:06:55,980 --> 00:06:58,980 We'll get an error until we implement the interface functions. 72 00:07:14,480 --> 00:07:18,580 Android studio can generate the stub for the implementation function 73 00:07:18,580 --> 00:07:21,080 just below the OnDateSet function, 74 00:07:21,330 --> 00:07:22,530 then I'll add the code. 75 00:07:58,730 --> 00:08:00,390 If we get confirmation 76 00:08:00,690 --> 00:08:03,920 and the dialog calls OnPositiveDialogResult, 77 00:08:04,420 --> 00:08:07,080 we can tell the view model to delete the records. 78 00:08:08,070 --> 00:08:11,170 We'll get an error until we write the delete function 79 00:08:11,170 --> 00:08:13,670 in the DurationsViewModel class, of course, 80 00:08:14,070 --> 00:08:15,370 I'll put it right at the end. 81 00:09:14,870 --> 00:09:16,270 That's the code finished. 82 00:09:16,730 --> 00:09:20,170 In the next video, we'll run the app and test it. 83 00:09:20,170 --> 00:09:21,070 I'll see you there.