1 00:00:01,160 --> 00:00:03,220 OK let's not write them off on a list. 2 00:00:03,540 --> 00:00:09,090 So in the last lesson bilabiate brought another list is an buter looked at few methods from the list 3 00:00:09,090 --> 00:00:11,820 interface and also in this class. 4 00:00:11,820 --> 00:00:16,260 So in this demo we'll be looking at all of those methods and we You'll also look at a few methods from 5 00:00:16,260 --> 00:00:19,900 the collection interface which is the root interface. 6 00:00:19,950 --> 00:00:25,680 So for this demo I have created this new package called Comdex semantics credit collections and I have 7 00:00:25,680 --> 00:00:29,080 also created a new class within that package called list them all. 8 00:00:29,490 --> 00:00:34,440 And within the this demo class we have this method called us our deadliest demo which we are going to 9 00:00:34,560 --> 00:00:36,070 fill in this in this demo. 10 00:00:36,150 --> 00:00:40,920 So we are going to write some code here and it's a pirate's topic matter that is invoked from the main 11 00:00:40,920 --> 00:00:42,060 method. 12 00:00:42,300 --> 00:00:43,880 So we're going to write some code. 13 00:00:44,100 --> 00:00:47,420 And we also have some code that has already been written. 14 00:00:47,940 --> 00:00:50,810 So that is done in the interest of time. 15 00:00:50,840 --> 00:00:55,150 So when we get here we'll be just looking at the court and we'll just run the program. 16 00:00:55,500 --> 00:00:58,430 But before doing that we will write some code here. 17 00:00:58,440 --> 00:01:01,080 So let's go ahead and first let's create an idealist 18 00:01:01,080 --> 00:01:06,630 . 19 00:01:08,510 --> 00:01:08,880 OK. 20 00:01:08,880 --> 00:01:15,150 He had the name of the artlessness list one and here that referenced this collection which is an interface 21 00:01:15,690 --> 00:01:21,390 and we have created an Adela's OK so we should always try to program plan interface. 22 00:01:21,390 --> 00:01:25,640 We know that because if you do that we can easily change the implementation. 23 00:01:25,680 --> 00:01:32,110 So if we want to use linguist all we need to do is change this to a linked list and collection interface 24 00:01:32,110 --> 00:01:33,390 since it is the root interface. 25 00:01:33,420 --> 00:01:36,040 It gives us the maximum generality. 26 00:01:36,270 --> 00:01:38,250 And we know that these facts are related to generics. 27 00:01:38,250 --> 00:01:39,520 So let's not worry about it. 28 00:01:39,660 --> 00:01:45,300 But for now it would suffice to understand that since we have integer here in between the stocks it 29 00:01:45,300 --> 00:01:47,860 means that it's an other list of India. 30 00:01:48,090 --> 00:01:52,090 So this list this particular analyst can store only integers. 31 00:01:52,260 --> 00:01:57,780 So if we try to add any other object other than an integer then we get a compiler error. 32 00:01:57,780 --> 00:02:02,030 Now if you want to Ardelia's to store to store on these strings then we simply have to change just a 33 00:02:02,040 --> 00:02:02,900 string. 34 00:02:03,060 --> 00:02:05,830 And if it needs to be double we just change it to double. 35 00:02:06,400 --> 00:02:10,010 So in that sense it is genetic. 36 00:02:10,050 --> 00:02:16,280 So the idealist can store anything any any particular object and all we need to do is do this through 37 00:02:16,280 --> 00:02:20,390 of genetics notation we need to indicate the kind of objects that we want to store. 38 00:02:20,640 --> 00:02:23,240 And that's the reason why it is Carlist genetics. 39 00:02:23,430 --> 00:02:27,970 It makes our Clausius genetic to distort anything anything that we want. 40 00:02:28,290 --> 00:02:31,190 So that's about it for now with regard to genetics. 41 00:02:31,240 --> 00:02:33,310 And we will discuss it when we get there. 42 00:02:33,690 --> 00:02:34,790 But all that he does. 43 00:02:35,070 --> 00:02:39,210 So let's just go ahead and add few elements to do this or at least 44 00:02:45,660 --> 00:02:46,060 sort of. 45 00:02:46,090 --> 00:02:47,780 I do. 46 00:02:48,270 --> 00:02:50,420 Let's add a duplicate here. 47 00:02:50,810 --> 00:02:56,450 And let's And not since honorless can store both duplicates as well as null. 48 00:02:56,730 --> 00:02:59,880 Let's go ahead and print the elements. 49 00:02:59,890 --> 00:03:03,700 No the mirror on it. 50 00:03:04,500 --> 00:03:09,900 So as you can see they're distorting all these elements and it can store duplicate as well as other 51 00:03:09,900 --> 00:03:11,190 values. 52 00:03:11,190 --> 00:03:15,340 Now let's go ahead and remove the element at that third index. 53 00:03:15,360 --> 00:03:18,290 This is 0 1 2 and 3 it needs to remove this one. 54 00:03:18,300 --> 00:03:27,570 So let's go ahead and say at least one board read more. 55 00:03:27,570 --> 00:03:31,030 So that element or that third position has been removed. 56 00:03:31,390 --> 00:03:35,510 Now the set list. 57 00:03:35,760 --> 00:03:37,520 So let's do this one more time. 58 00:03:37,590 --> 00:03:47,760 In that case it has to remove the value knowledge since it is at the third position in 0 1 2 and 3. 59 00:03:47,910 --> 00:03:53,820 Now as you can see it did not remove nutten but it removed the elementary. 60 00:03:53,820 --> 00:03:58,880 So the reason for that is because it is due to metal binding. 61 00:03:58,950 --> 00:04:04,620 If you recall our lesson on method binding we said that there is this method signature binding which 62 00:04:04,620 --> 00:04:06,990 happens at compile time itself. 63 00:04:06,990 --> 00:04:12,900 So at compile time the compiler is looking at the reference type which is collection in this case and 64 00:04:12,900 --> 00:04:17,200 collection has this method called remote island. 65 00:04:17,250 --> 00:04:19,140 It has this parameter object. 66 00:04:19,140 --> 00:04:27,210 So at compile time the compiler will try to find an exact match a method with which has the exact parameter 67 00:04:27,210 --> 00:04:28,760 which is an NPR remote off. 68 00:04:28,770 --> 00:04:32,570 And but the collection interface does not have that method. 69 00:04:32,700 --> 00:04:37,010 The removal of a method is present only in the list interface. 70 00:04:37,170 --> 00:04:39,130 Ok but not in the collection interface. 71 00:04:39,480 --> 00:04:45,870 But then compiler sees that it did not find the exact match and method with the exact matching signature 72 00:04:45,900 --> 00:04:49,470 but it found a method having compatible signature. 73 00:04:49,630 --> 00:04:55,770 OK so in that case in the bike code it's going to write that the method that needs to be invoked should 74 00:04:55,770 --> 00:04:56,840 have the signature. 75 00:04:56,970 --> 00:04:58,860 OK I don't mind the JVM. 76 00:04:58,860 --> 00:05:06,420 Well really try to find the most specific method having the signature which is also present in the list 77 00:05:06,450 --> 00:05:08,880 interface in other districts. 78 00:05:09,450 --> 00:05:15,900 So if you don't recall just go back to the coalescent on method binding and you can under the topic 79 00:05:15,900 --> 00:05:18,600 on the method signature binding will explain this. 80 00:05:18,600 --> 00:05:19,130 So. 81 00:05:19,130 --> 00:05:19,890 So that's about it. 82 00:05:19,890 --> 00:05:21,400 So that's the reason why. 83 00:05:21,660 --> 00:05:27,570 So actually even when we invoke up here in the first instance it was not removing the element of purpose 84 00:05:27,700 --> 00:05:27,900 . 85 00:05:27,930 --> 00:05:30,960 But it was actually removing the element 3 itself. 86 00:05:30,990 --> 00:05:31,740 OK. 87 00:05:31,860 --> 00:05:35,220 And the same happened here it remove are the elementary. 88 00:05:35,220 --> 00:05:42,600 Now if you want to make make it are the element at the Toti next door be removed then we need to change 89 00:05:42,600 --> 00:05:44,090 this list. 90 00:05:44,130 --> 00:05:50,480 In fact let's change it to list and that's because the the methods that we are going to invoke math 91 00:05:50,500 --> 00:05:50,580 . 92 00:05:50,640 --> 00:05:56,250 Next we are going to write next are specific to our position specific methods. 93 00:05:56,430 --> 00:06:02,740 So we each have an index number as the parameter on disposition specific methods are specified only 94 00:06:02,750 --> 00:06:04,550 and the list interface. 95 00:06:04,800 --> 00:06:10,890 Now if I run this you can see the non-God to look at which means that it didn't work the method. 96 00:06:11,370 --> 00:06:13,720 This particular mother more off and. 97 00:06:13,920 --> 00:06:14,710 OK. 98 00:06:14,910 --> 00:06:21,780 So that's that's the metric signature of a lot of people in order to understand that how them at their 99 00:06:21,780 --> 00:06:23,440 signature binding works. 100 00:06:23,490 --> 00:06:29,250 So you can go back and refer to that particular lecture and object oriented programming. 101 00:06:29,250 --> 00:06:34,730 Now let's go ahead and write some positions specific methods. 102 00:06:36,660 --> 00:06:40,820 Let's add an element at zero. 103 00:06:42,780 --> 00:06:45,450 So you have a new element here added at zero. 104 00:06:45,600 --> 00:06:46,680 It's. 105 00:06:46,800 --> 00:06:51,060 So that's the I'd mutter that an index here is zero. 106 00:06:51,060 --> 00:06:55,960 Now let's try the set matter. 107 00:06:56,490 --> 00:07:03,690 So let's set the element of zero position with just 10 to nine. 108 00:07:03,700 --> 00:07:10,230 There you go so nine has been added and this method would return the previous elements stored at that 109 00:07:10,230 --> 00:07:12,010 position which would be then. 110 00:07:12,030 --> 00:07:16,280 OK so these are the new elements that we have 9 1 2 and 3. 111 00:07:16,350 --> 00:07:18,940 So those are the items segment. 112 00:07:19,090 --> 00:07:21,790 Now let's look at some bulk operations. 113 00:07:21,900 --> 00:07:25,060 So we know that the collection interface are some bulk methods. 114 00:07:25,200 --> 00:07:26,670 So here it is. 115 00:07:26,670 --> 00:07:27,900 So let me uncomment this. 116 00:07:27,930 --> 00:07:29,280 So it's already there. 117 00:07:29,280 --> 00:07:31,300 So here we are creating a new list. 118 00:07:31,500 --> 00:07:31,800 OK. 119 00:07:31,810 --> 00:07:32,610 In New Collection. 120 00:07:32,610 --> 00:07:39,580 It's called us let's do I've got two elements 9 and three iron from list 1. 121 00:07:39,660 --> 00:07:45,760 We are woking we are invoking the remove all method on list 1 and we are passing listed as the input 122 00:07:45,810 --> 00:07:47,710 barometer input argument. 123 00:07:47,760 --> 00:07:51,330 So we want to remote If list one has both these elements. 124 00:07:51,330 --> 00:07:53,800 We want to remove them from list 1. 125 00:07:54,450 --> 00:07:57,750 So let me just run this. 126 00:07:58,240 --> 00:08:01,960 So we only lost 100 only 9 1 2 and 3. 127 00:08:02,160 --> 00:08:03,770 So list 2 had 9 and 3. 128 00:08:03,780 --> 00:08:05,620 So we have removed the bench. 129 00:08:05,700 --> 00:08:07,840 So we are left with only one and 2. 130 00:08:08,220 --> 00:08:09,500 Now go let's go. 131 00:08:09,600 --> 00:08:11,800 Iron I have one Boulis too. 132 00:08:11,820 --> 00:08:14,390 So let's to had already had nine and three. 133 00:08:14,400 --> 00:08:17,890 Let's also add one to it and let's. 134 00:08:17,970 --> 00:08:19,490 In order to retain All-Met there. 135 00:08:19,530 --> 00:08:23,370 So we'll have more on NEXT is reading all matter. 136 00:08:23,400 --> 00:08:25,030 Here it is written on. 137 00:08:25,380 --> 00:08:26,270 So read in. 138 00:08:26,270 --> 00:08:32,310 All well written all the elements present and list do on that word remove all the remaining elements 139 00:08:32,330 --> 00:08:32,480 . 140 00:08:32,640 --> 00:08:41,330 OK so list one right now has only 1 1 and 2 and a list to list one has one undo unless Drew has a 93 141 00:08:41,340 --> 00:08:42,220 on one. 142 00:08:42,330 --> 00:08:44,060 So the only common element is 1. 143 00:08:44,190 --> 00:08:47,700 So it will retain that and really move to. 144 00:08:47,820 --> 00:08:48,670 Here it is. 145 00:08:48,720 --> 00:08:53,570 So it retained one deleted element. 146 00:08:54,300 --> 00:08:56,340 So we are done with the remote all undereating on. 147 00:08:56,340 --> 00:08:58,220 Let's look at at all. 148 00:08:58,290 --> 00:09:01,330 So let's just go ahead and simply add the elements off list to do list 1 149 00:09:04,560 --> 00:09:12,100 because you can see the three elements mind three and one which were part of list 2 are ordered to list 150 00:09:12,170 --> 00:09:12,900 1. 151 00:09:12,930 --> 00:09:15,160 So that's the ideal method. 152 00:09:15,240 --> 00:09:18,270 And let's also do this. 153 00:09:18,300 --> 00:09:21,080 So this is just pure setting the value. 154 00:09:21,180 --> 00:09:28,810 Enlist one element at indexable they do is reset to two which means that this tree gets changed to sort 155 00:09:28,810 --> 00:09:31,620 of try on it once again. 156 00:09:31,620 --> 00:09:34,350 And here it is here. 157 00:09:34,390 --> 00:09:41,160 The set met there simply returns the search the value at that particular index to do under the previous 158 00:09:41,160 --> 00:09:44,190 element the previous element of the next Wall Street. 159 00:09:44,190 --> 00:09:45,340 So it's district running back. 160 00:09:45,360 --> 00:09:47,360 So you're just printing out that value. 161 00:09:47,730 --> 00:09:49,140 So those are the bulk operations. 162 00:09:49,170 --> 00:09:51,200 And this was just a set operation. 163 00:09:51,240 --> 00:09:54,540 Now let's go ahead and look at some such methods. 164 00:09:54,630 --> 00:10:01,220 Here we are so the first one as the contains mentored and we are just checking if the element one is 165 00:10:01,220 --> 00:10:08,930 present and the last one second is index off which gives the first utterance of the element of the next 166 00:10:08,930 --> 00:10:12,710 number of the first occurrence of this particular element if it is present. 167 00:10:12,770 --> 00:10:18,350 If not it would read and a minus one third one is lost and next off which would give the last index 168 00:10:18,350 --> 00:10:21,090 off the goodness of this element. 169 00:10:21,140 --> 00:10:23,010 So let's run this. 170 00:10:23,500 --> 00:10:29,520 Now as you can see the element 1 is present and the last one and the last one. 171 00:10:29,570 --> 00:10:32,960 So it returns a true here on the index position. 172 00:10:32,960 --> 00:10:34,630 When we do index off it is zero. 173 00:10:34,640 --> 00:10:41,160 But when we do the last index off it gives three because the last element here is one. 174 00:10:41,210 --> 00:10:41,450 OK. 175 00:10:41,450 --> 00:10:44,220 So it gives up in next three. 176 00:10:44,240 --> 00:10:45,980 So those are the search operations. 177 00:10:45,980 --> 00:10:49,470 Now we also discussed a broader range view the sublist method. 178 00:10:49,820 --> 00:10:51,890 So let's also try that. 179 00:10:53,030 --> 00:10:56,700 So range rules just because that's part of the list interface listen. 180 00:10:56,870 --> 00:11:06,890 So here we are calling the sublist matter and we are saying we are asking for a sublist and the element 181 00:11:07,220 --> 00:11:13,120 indexes are the lets us do the two indexes three so it will return only one element Element 2. 182 00:11:13,120 --> 00:11:14,590 Because this is exclusive. 183 00:11:14,870 --> 00:11:18,450 So the the name of this list is list 3. 184 00:11:18,450 --> 00:11:20,420 That's the sublist. 185 00:11:20,450 --> 00:11:23,440 We said that the list 3 when we do a sublist. 186 00:11:23,480 --> 00:11:29,200 This particular list is backed up by the origin of that original idlest which is a list 1. 187 00:11:29,380 --> 00:11:34,760 So which means that any changes that we make to this new list will be reflected in that list. 188 00:11:35,330 --> 00:11:38,920 So let's go ahead and run this. 189 00:11:39,230 --> 00:11:40,460 Here it is. 190 00:11:41,090 --> 00:11:50,270 So in the list 3 Initially it had only it had only the element at index position to know we are setting 191 00:11:50,270 --> 00:11:54,020 it to 6 and we are printing list one here. 192 00:11:54,050 --> 00:12:01,100 So as you can see when we have said the value industry it also got to reflect it and list one on that 193 00:12:01,100 --> 00:12:05,850 particular value at position you got updated. 194 00:12:05,930 --> 00:12:06,490 OK. 195 00:12:06,860 --> 00:12:09,860 Now we are updating the value we are. 196 00:12:09,860 --> 00:12:13,030 I think a value to list three. 197 00:12:13,270 --> 00:12:17,010 Now when we do that it also gets reflected in list 1. 198 00:12:17,180 --> 00:12:18,270 So we're adding it. 199 00:12:18,380 --> 00:12:24,770 The position zero but that position zero is actually the index position to and list one. 200 00:12:24,770 --> 00:12:30,890 So as you can see the elements 7 what I did on the other two elements got shifted to right. 201 00:12:31,120 --> 00:12:37,250 So any change that you'll make in this new list will be reflected in that and that put you in the back 202 00:12:37,500 --> 00:12:41,890 of a list which is the original list which just listed them. 203 00:12:41,990 --> 00:12:45,350 So we have made some changes in the new order list in the sublist. 204 00:12:45,350 --> 00:12:46,890 And that got reflected here. 205 00:12:46,930 --> 00:12:53,540 No need to make some change in the original list and see that it gets reflected in the industry. 206 00:12:53,570 --> 00:12:55,560 So here we are making a change. 207 00:12:55,630 --> 00:13:03,350 We are setting we are resetting the value of the element at position to 8 under to see if it gets reflected 208 00:13:03,350 --> 00:13:05,370 in industry. 209 00:13:05,420 --> 00:13:06,980 So we are printing a history here. 210 00:13:06,980 --> 00:13:13,630 And as you can see the history the value at zero at the position index 0 got changed to 8. 211 00:13:13,850 --> 00:13:18,520 So the change was made in this one and it got reflected in history. 212 00:13:18,770 --> 00:13:27,260 Now let's see if we can I add an element and last one on whether it gets reflected in industry. 213 00:13:27,770 --> 00:13:36,120 So we're adding an element at index position zero in the last one and it doesn't. 214 00:13:36,130 --> 00:13:40,120 So we are we have we just tried to add an element and to list one. 215 00:13:40,340 --> 00:13:46,260 But when we tried to prend the elements of history it did not look. 216 00:13:46,490 --> 00:13:51,200 So we can only make non-structural changes in a just one. 217 00:13:51,230 --> 00:13:54,700 Only then we can access the elements in history. 218 00:13:54,710 --> 00:13:59,360 Now let's say we made a structural change here a structural changes adding an element or deleting an 219 00:13:59,360 --> 00:14:06,260 element and when we do that then if we try to do when we try to access any of them at industry then 220 00:14:06,260 --> 00:14:09,950 we get an exception under System and modification exception. 221 00:14:09,950 --> 00:14:18,140 So anything we can do as analyst one we can or we can set something in that case it is fine but if we 222 00:14:18,130 --> 00:14:24,100 make any structural change in the back array then the new order the sublist will throw an exception 223 00:14:24,110 --> 00:14:26,610 when we try to access any of its methods. 224 00:14:27,320 --> 00:14:28,790 So that's the thing. 225 00:14:29,210 --> 00:14:33,140 But if we make any changes in the in the sublist then it is fine. 226 00:14:33,140 --> 00:14:36,050 We can I'd also be we can make structural changes. 227 00:14:36,050 --> 00:14:39,830 Also industry then that gets reflected in last one. 228 00:14:40,020 --> 00:14:40,690 Okay. 229 00:14:40,900 --> 00:14:42,730 So that's the thing. 230 00:14:42,730 --> 00:14:46,030 Now let me uncommon this. 231 00:14:46,120 --> 00:14:52,010 I think we are just printing the same elements not as it it through the elements of the of the list 232 00:14:52,010 --> 00:14:52,180 . 233 00:14:52,190 --> 00:14:57,340 So we are simply having a For Each loop here. 234 00:14:59,300 --> 00:15:02,740 But let me just Carmen this note. 235 00:15:03,130 --> 00:15:04,590 My read on it. 236 00:15:05,270 --> 00:15:10,560 So as you can see we are just iterating through the elements and I'm just printing all these five elements 237 00:15:10,610 --> 00:15:12,280 and the last one. 238 00:15:12,320 --> 00:15:14,660 Now let's see if element is nine. 239 00:15:14,690 --> 00:15:17,520 So the 11 element minus here the second element. 240 00:15:17,670 --> 00:15:22,270 Let's say we want to remove that element from the last one. 241 00:15:22,280 --> 00:15:22,720 OK. 242 00:15:22,790 --> 00:15:24,480 So we are iterating through last one. 243 00:15:24,740 --> 00:15:30,440 But if the element current element happens to be 9 we want to read more and see what happens. 244 00:15:30,950 --> 00:15:32,940 As you can see we get an exception here. 245 00:15:33,020 --> 00:15:35,370 It's a concussion modification exception. 246 00:15:35,730 --> 00:15:40,420 So and So that element 1 got printed here here and then element 9. 247 00:15:40,430 --> 00:15:41,720 The second element was 9. 248 00:15:41,750 --> 00:15:47,570 It also got printed but if element is nine we are trying to remove it and then it throws in concurrent 249 00:15:47,570 --> 00:15:49,400 modification exception. 250 00:15:49,390 --> 00:15:54,920 So the thing is when we are iterating if we want to remove a particular element during the iteration 251 00:15:55,550 --> 00:15:57,920 then we cannot do it using a for each statement. 252 00:15:58,040 --> 00:16:03,320 And for that we need to use it for that matter which is the subject of next lesson. 253 00:16:03,400 --> 00:16:03,980 OK. 254 00:16:03,980 --> 00:16:04,800 Using an editor to. 255 00:16:04,810 --> 00:16:05,970 We can do that. 256 00:16:06,050 --> 00:16:08,550 And so that we will see in the next lesson. 257 00:16:08,650 --> 00:16:09,310 So thank you. 258 00:16:09,320 --> 00:16:13,400 And this code is available in the resources section for download and you can download our and you can 259 00:16:13,390 --> 00:16:15,150 run it on happy coding. 260 00:16:15,140 --> 00:16:16,450 And thank you.