1 00:00:05,200 --> 00:00:06,200 Welcome back. 2 00:00:06,500 --> 00:00:10,000 We're now ready to change our MainActivityFragment class 3 00:00:10,400 --> 00:00:14,600 to restore the SwipeTask if the user cancels the deletion. 4 00:00:20,850 --> 00:00:23,150 The RecyclerView will do most of the work. 5 00:00:23,650 --> 00:00:27,350 All we have to do is call NotifyItemChanged 6 00:00:27,350 --> 00:00:28,350 on our adapter. 7 00:00:29,050 --> 00:00:31,350 The RecyclerView observes its adapter 8 00:00:31,350 --> 00:00:34,250 and will redraw the item that was removed from the list. 9 00:00:35,050 --> 00:00:37,350 We need to tell it which item was changed, 10 00:00:37,710 --> 00:00:40,010 and we do that by passing the position 11 00:00:40,310 --> 00:00:43,310 when we call NotifyItemChanged. 12 00:00:44,200 --> 00:00:46,100 I'm going to write this code backwards. 13 00:00:46,760 --> 00:00:49,960 Now I don't mean I'm going to be typing nuf instead of fun. 14 00:00:50,360 --> 00:00:54,660 I'm going to assume we have the items position and write the code to use it. 15 00:00:55,210 --> 00:00:59,760 We'll worry about getting the position once we've seen how we're going to use it. 16 00:01:00,460 --> 00:01:03,450 I think it will be easier to understand that bit of code 17 00:01:03,450 --> 00:01:05,650 if we've seen what we're trying to do. 18 00:01:06,850 --> 00:01:09,850 We'll restore the item the DeletedTask 19 00:01:09,850 --> 00:01:13,420 in the dialogues onNegativeDialogResult function 20 00:01:14,020 --> 00:01:17,220 that's called when the user taps the dialog's cancel button. 21 00:01:18,420 --> 00:01:22,220 I'll use control O to generate the function after 22 00:01:22,220 --> 00:01:24,220 OnPositiveDialogResult. 23 00:02:51,220 --> 00:02:53,120 On line 126, 24 00:02:53,270 --> 00:02:56,770 we'll call the adapter's NotifyItemChanged function 25 00:02:57,170 --> 00:02:59,570 passing in the position of the item that changed. 26 00:03:00,270 --> 00:03:02,630 That's the position of the task that was swiped. 27 00:03:03,290 --> 00:03:05,890 It should be obvious from line 123 28 00:03:05,890 --> 00:03:09,090 that we're going to pass the position in the dialog's arguments. 29 00:03:09,970 --> 00:03:13,470 The arguments are passed into this function in the args bundle. 30 00:03:13,970 --> 00:03:16,170 We've seen this before a few times now. 31 00:03:17,170 --> 00:03:20,570 I'll create the DialogTaskPosition constant 32 00:03:20,930 --> 00:03:23,130 up with the others at the top of the file. 33 00:03:44,130 --> 00:03:48,230 Okay. That's fixed the error. Of course, the code won't work yet. 34 00:03:48,730 --> 00:03:51,720 We haven't added the position to the dialog's arguments. 35 00:03:52,380 --> 00:03:56,380 The dialog is created in our OnDeleteClick function, 36 00:03:56,980 --> 00:03:59,180 so that's where we'll add the position to the bundle. 37 00:04:27,780 --> 00:04:30,780 The OnDeleteClick will get the position as an argument, 38 00:04:31,440 --> 00:04:34,540 it then puts it into the bundle ready for us to retrieve 39 00:04:34,540 --> 00:04:36,340 if the deletion is cancelled. 40 00:04:37,540 --> 00:04:40,240 Now we're left with the problem of how to get the position. 41 00:04:41,120 --> 00:04:43,120 Fortunately, that's easy. 42 00:04:43,120 --> 00:04:45,420 It's an attribute of the ViewHolder 43 00:04:45,420 --> 00:04:48,020 that's passed to the OnSwiped function. 44 00:04:48,620 --> 00:04:52,420 Let's have a look at that function. Up on line 74, 45 00:04:54,620 --> 00:04:56,920 we get past two arguments; 46 00:04:57,520 --> 00:04:59,720 the ViewHolder of the item that was swiped 47 00:05:00,270 --> 00:05:02,270 and the direction in which it was swiped. 48 00:05:03,070 --> 00:05:07,170 Passing the ViewHoldersAdapter position to OnDeleteClick 49 00:05:07,470 --> 00:05:08,470 will fix the error. 50 00:05:08,830 --> 00:05:10,080 On line 78. 51 00:05:22,880 --> 00:05:25,180 We get the position in OnSwiped 52 00:05:25,180 --> 00:05:28,180 and we pass it to our OnDeleteClicked function. 53 00:05:28,980 --> 00:05:32,480 That puts it into the dialog's bundle, so that we can retrieve it 54 00:05:32,480 --> 00:05:36,080 in the OnNegativeDialogResult function and use it 55 00:05:36,080 --> 00:05:38,880 when we call NotifyItemChanged. 56 00:05:39,680 --> 00:05:43,280 The RecyclerView and RecycleRviewAdapter classes 57 00:05:43,280 --> 00:05:45,780 were designed with this kind of use in mind, 58 00:05:46,180 --> 00:05:49,180 which makes it very easy to implement swiping operations. 59 00:05:50,170 --> 00:05:54,370 Let's see if it works. Run the application and swipe the task. 60 00:05:58,670 --> 00:06:01,570 Notice that it disappears from the RecyclerView 61 00:06:01,570 --> 00:06:04,970 before the dialog appears. That's how swiping works 62 00:06:05,370 --> 00:06:09,770 but it's still in the database and it also still exists in the adapter. 63 00:06:10,170 --> 00:06:11,770 We haven't deleted it yet. 64 00:06:12,370 --> 00:06:15,370 It's only the RecyclerViewsDisplay that's changed. 65 00:06:15,970 --> 00:06:16,960 Tap cancel 66 00:06:19,660 --> 00:06:21,160 and the task reappears. 67 00:06:21,960 --> 00:06:23,860 Okay. All that's left to do 68 00:06:23,860 --> 00:06:26,840 is edit the task list items layout and delete 69 00:06:27,140 --> 00:06:29,040 the delete button. 70 00:06:29,740 --> 00:06:33,540 That will leave the tli edit button unconstrained 71 00:06:33,940 --> 00:06:36,640 so constrain it to the right edge of the layout 72 00:06:36,640 --> 00:06:38,300 with a margin of 8DP. 73 00:06:38,800 --> 00:06:41,900 Its top constraint should be to the top of the layout 74 00:06:41,900 --> 00:06:44,100 again with the margin of 8dp. 75 00:07:15,100 --> 00:07:19,000 Clicking the plus icons in the constraint widget diagram on the right 76 00:07:19,000 --> 00:07:21,200 is a quick way to create those constraints 77 00:07:21,600 --> 00:07:25,960 but watch the margins and change them to 8 if another value is assigned. 78 00:07:26,860 --> 00:07:29,220 Run the app again and test it thoroughly. 79 00:07:46,220 --> 00:07:49,520 When you've found the bug your challenge is to fix it. 80 00:08:03,320 --> 00:08:07,020 Here's a hint: try swiping to delete the task that's being edited 81 00:08:07,220 --> 00:08:08,720 when you're in landscape mode. 82 00:08:09,080 --> 00:08:12,580 I'll go over my solution in the next video. I'll see you there.