1 00:00:05,240 --> 00:00:09,760 so lets just run this program again just to make sure that it is showing the four 2 00:00:09,760 --> 00:00:14,940 field variables that we have defined and you can see down their we got the fourth fields putting 3 00:00:14,940 --> 00:00:19,570 up the artist field the album field the year field and the song field so that's 4 00:00:19,570 --> 00:00:25,000 working fine so the first approach that I'll take to putting 5 00:00:25,000 --> 00:00:29,380 the data into the classes follows naturally from the data in other words 6 00:00:29,380 --> 00:00:34,730 as each row is read we are gonna create a song object and then add that to the album and when 7 00:00:34,730 --> 00:00:38,790 a new album is found in the data the current album is gonna be stored in the 8 00:00:38,790 --> 00:00:43,960 artist's album list and a new album object created with that current rows 9 00:00:43,960 --> 00:00:49,130 details and likewise the same things can happen when a record for a new artist is 10 00:00:49,130 --> 00:00:55,200 read the current artist is gonna be saved in the artists list and new artist objects 11 00:00:55,200 --> 00:01:00,660 is gonna be then created with the data in the current row and we are gonna put all the code to populate 12 00:01:00,660 --> 00:01:05,129 the objects from the data file in a function and that function will return a list 13 00:01:05,129 --> 00:01:11,570 of artists objects when we are finishing processing the file so lets start by expanding the 14 00:01:11,570 --> 00:01:15,900 existing code that we got in our load data so we got this code we wrote 15 00:01:15,900 --> 00:01:23,920 in the previous video I'm gonna change this a bit now actually what will do is change it 16 00:01:23,920 --> 00:01:28,960 a little bit lets just expanded and put some formatting in their so its easier to read so 17 00:01:28,960 --> 00:01:31,960 I'm going to add some formatting code..... 18 00:01:38,550 --> 00:02:25,600 .... 19 00:02:25,600 --> 00:02:36,600 ....and what that means 20 00:02:36,600 --> 00:02:42,460 at this point is that we just read details for a new artist so we've just read 21 00:02:42,460 --> 00:02:51,250 details from new artist so what we want to do their is to store the current album in 22 00:02:51,250 --> 00:02:56,070 the current artist collection and create a new artist object so will just put our 23 00:02:56,070 --> 00:02:59,070 documentation..... 24 00:03:00,560 --> 00:03:03,880 .... 25 00:03:05,030 --> 00:03:32,730 ..... 26 00:03:32,730 --> 00:03:39,150 .... 27 00:03:39,790 --> 00:03:45,230 .... 28 00:03:45,230 --> 00:03:55,590 .....and then moving down here so we are going to do 29 00:03:55,590 --> 00:04:05,310 a test here....remembering the previous if was on line 30 00:04:05,310 --> 00:04:10,340 94 we are testing for artists we are not doing the test for album so.... 31 00:04:10,340 --> 00:04:17,760 .... 32 00:04:17,760 --> 00:04:33,860 ..... 33 00:04:33,860 --> 00:04:44,830 .... 34 00:04:44,830 --> 00:04:49,360 ....just like before when we are reading details about a new artist in this case we've just read a 35 00:04:49,360 --> 00:04:54,750 new album for the current artists so.... 36 00:04:54,750 --> 00:04:57,860 .... 37 00:04:57,860 --> 00:05:07,020 ....so we want to store the current album in 38 00:05:07,020 --> 00:05:15,910 the artist collection and then create a new album object so.... 39 00:05:15,910 --> 00:06:01,090 .... 40 00:06:01,090 --> 00:06:06,440 ... 41 00:06:06,440 --> 00:06:15,860 .... 42 00:06:19,410 --> 00:06:39,910 .... 43 00:06:39,910 --> 00:06:49,690 ....ok so that is 44 00:06:49,690 --> 00:06:53,950 going through the entire code going through the entire text file albums.txt 45 00:06:53,950 --> 00:07:00,160 which we started doing it or started the with open on line 87 so 46 00:07:00,160 --> 00:07:05,280 down here then what we want to do after we finished reading the last line of 47 00:07:05,280 --> 00:07:09,010 that albums.txt text file then we're gonna have an artist and an album that 48 00:07:09,010 --> 00:07:17,470 haven't been stored so we need to do that now so... 49 00:07:17,470 --> 00:07:43,170 ..... 50 00:07:44,920 --> 00:07:53,390 ... 51 00:07:53,390 --> 00:08:12,490 .... 52 00:08:13,750 --> 00:08:22,900 .... 53 00:08:22,900 --> 00:08:41,929 ..... 54 00:08:41,929 --> 00:08:48,480 ....so we want the 4 to execute to go 55 00:08:48,480 --> 00:08:53,490 through the entire file then this code here is going to start executing after that 56 00:08:53,490 --> 00:08:57,560 4 is complete so its process the file and we are just processing the last line there 57 00:08:57,560 --> 00:09:02,620 that's fixed that up and then returning as I mentioned the artist list that we've 58 00:09:02,620 --> 00:09:08,030 created from this code from reading in that file one thing to be aware of 59 00:09:08,030 --> 00:09:12,690 with this approach is that the objects aren't stored in their collections until a new 60 00:09:12,690 --> 00:09:16,620 record is read from the file now for example the current album is only added 61 00:09:16,620 --> 00:09:22,110 to the artists album list when a record containing a different album is read that's 62 00:09:22,110 --> 00:09:26,210 just the way that we set this up to process so ultimately what that means is the 63 00:09:26,210 --> 00:09:30,920 last set of data won't be stored and that's why I've added this code from line 118 64 00:09:30,920 --> 00:09:36,320 down to process that lasted bit of code to check if theirs a valid artist object on that 65 00:09:36,320 --> 00:09:40,760 last line adds that to the global list of artist and also adds the current album 66 00:09:40,760 --> 00:09:46,970 the last one read into the artists list of albums so let's make a change so we just load data 67 00:09:46,970 --> 00:09:55,180 here so lets test to see whether this works and we are going to do it differently we gonna put.... 68 00:09:55,180 --> 00:10:04,890 ...so we are gonna save the result the artist list that has been returned and print out how many their is so... 69 00:10:04,890 --> 00:10:07,890 .... 70 00:10:09,320 --> 00:10:19,480 ....so lets running this and see what happens we can see it says 71 00:10:19,480 --> 00:10:24,050 there's twenty eight artist and that seems to be working ok but how can we have be 72 00:10:24,050 --> 00:10:28,530 sure that it is well theirs a number of ways we could validate the data contained 73 00:10:28,530 --> 00:10:32,760 in the artist the album the song objects but this sort of checking is probably 74 00:10:32,760 --> 00:10:37,160 best left to the computer because the ability to compare two or more files has 75 00:10:37,160 --> 00:10:40,780 been provided with most operating systems for years but rather than using 76 00:10:40,780 --> 00:10:45,980 command-line tools we can do we can now used the compare files feature 77 00:10:45,980 --> 00:10:50,120 of IntelliJ to do this comparison for us much better to get the computer to be 78 00:10:50,120 --> 00:10:54,130 doing this sort of comparison checking rather than using you 79 00:10:54,630 --> 00:10:58,640 know ourselves to do that so to achieve this all we really have to do is use our objects to 80 00:10:58,640 --> 00:11:03,730 write a new file in the same format as the original and getting IntelliJ to check 81 00:11:03,730 --> 00:11:05,580 for differences 82 00:11:05,580 --> 00:11:10,290 so lets go and write a function to write the check file and then we are gonna call it in the main program 83 00:11:10,290 --> 00:11:20,470 after we got this print out here so close that down and write that method will start down here... 84 00:11:20,470 --> 00:11:28,930 ....so we define a file called... 85 00:11:28,930 --> 00:12:05,920 .... 86 00:12:06,830 --> 00:12:31,350 .... 87 00:12:31,350 --> 00:12:40,950 ..... 88 00:12:40,950 --> 00:13:27,020 .... 89 00:13:27,020 --> 00:13:32,890 ....and that really should be all we need to do to write that out and that should be in the same format as 90 00:13:32,890 --> 00:13:37,830 the original albums.txt files because we've printed it out and with 91 00:13:37,830 --> 00:13:44,010 the relevant information separated by tabs of course as the original file had so to 92 00:13:44,010 --> 00:13:51,330 test this we can then add a call after the print here.... 93 00:13:51,330 --> 00:14:03,460 .....so let's just run that you can see there 94 00:14:03,460 --> 00:14:11,710 I made a mistake in 1.name and I got a bracket there instead of a right brace.... 95 00:14:12,510 --> 00:14:21,190 and run it again....ok we've now got a check file txt that's been created so that's good we have just a quick 96 00:14:21,190 --> 00:14:25,070 look to see that it looks roughly the same theirs the original albums.txt 97 00:14:25,070 --> 00:14:31,560 check file does seem to look pretty good but lets end the video here and in the 98 00:14:31,560 --> 00:14:38,500 next video will start going through and we'll use IntelliJ compare files option to confirm 99 00:14:38,500 --> 00:14:41,150 that these files are identical so let's do that in the next video