WEBVTT 00:01.240 --> 00:01.780 Hi everyone. 00:01.780 --> 00:03.100 Welcome back to this tutorial. 00:03.100 --> 00:08.440 In this tutorial I will compare the collections with streams and highlight some of the key differences 00:08.440 --> 00:09.310 between them. 00:11.300 --> 00:12.260 As the table denotes. 00:12.260 --> 00:17.510 The left hand side represents a collection, and the right hand side represents the stream. 00:17.510 --> 00:18.350 In collections. 00:18.350 --> 00:21.470 We can add, remove and modify elements. 00:21.740 --> 00:28.400 That is not the case with streams you cannot modify or you cannot add elements to the stream. 00:28.400 --> 00:31.040 Once you have the stream created. 00:31.370 --> 00:33.860 Let's go ahead and run this by an example. 00:34.710 --> 00:36.690 Have the IntelliJ open in here. 00:36.690 --> 00:42.420 What I'm going to do, I'm going to create a class called Collection. 00:43.970 --> 00:47.250 Elections versus string. 00:48.180 --> 00:50.000 Want to make this class executable? 00:50.690 --> 00:52.040 Public static void Main. 00:53.040 --> 00:56.270 I want to put this in presentation mode so that the code will be clear. 00:58.080 --> 01:02.940 The first step, which I'm going to do, I'm going to create another list, which is a collection. 01:04.330 --> 01:07.800 Spring, then I'm going to name it as names. 01:07.810 --> 01:09.250 Let's import this. 01:10.420 --> 01:13.380 This one is going to be a new array list. 01:13.980 --> 01:15.600 So we have the instance ready. 01:15.610 --> 01:17.970 The next step is I'm going to add some elements to it. 01:17.980 --> 01:19.510 Name Dot Add. 01:19.960 --> 01:21.670 I'm going to add the name as Adam. 01:23.870 --> 01:25.460 The second name is going to be Jim. 01:26.120 --> 01:27.860 The third name is going to be Jenny. 01:28.400 --> 01:29.270 So. 01:30.100 --> 01:34.780 I created the collection here and then I added the elements here if we want to remove. 01:35.140 --> 01:40.150 Let's say I want to remove the element in the first index, I'm going to pass zero. 01:41.460 --> 01:42.840 Then if I do a print. 01:46.210 --> 01:47.170 It's going to. 01:48.130 --> 01:50.440 And only the two names, Jim and Jenny. 01:51.100 --> 01:56.860 So in collections you can add, you can remove or you can modify the values also. 01:57.340 --> 01:59.230 That is not the case with streams. 01:59.260 --> 02:04.360 What I'm going to do, I'm going to create a stream names, dot stream. 02:04.840 --> 02:09.940 As soon as I created this, it's going to give me access to all the stream methods it support. 02:10.660 --> 02:12.700 It's a Is there a method called Add? 02:13.060 --> 02:14.530 There are a method called remove. 02:15.330 --> 02:25.710 So scream doesn't allow you to add, modify or delete elements from the stream once it is created. 02:26.010 --> 02:27.660 That is the first thing which. 02:28.440 --> 02:29.880 We have to register in our mind. 02:30.780 --> 02:35.100 Let's go back to the presentation and talk about the remaining points in the table. 02:35.870 --> 02:43.820 The next point in the comparison is about accessing the elements from the collection and stream in collections. 02:43.970 --> 02:46.700 The elements can be accessed in any order. 02:46.730 --> 02:52.880 Let's say you have an array list of five elements and you want to check what's there in the fifth element. 02:52.970 --> 02:57.380 Then in that case you will use list dot get and you pass the index. 02:57.380 --> 03:00.110 So array list index starts from zero. 03:00.140 --> 03:06.050 You pass the index value as four, then it is going to give you the fifth element in that list. 03:06.760 --> 03:09.110 That is not the case in streams. 03:09.130 --> 03:14.590 In streams you can only access the elements one by one in a sequence. 03:16.070 --> 03:23.030 The next point is elections is eagerly constructed and streams are lazily constructed. 03:23.060 --> 03:24.230 What does it mean? 03:25.880 --> 03:31.400 It means that you have to populate the collection with the values if you want to manipulate it. 03:31.610 --> 03:37.130 That is not the case with strings unless and until a terminal operation is invoked. 03:37.160 --> 03:40.460 The stream doesn't starts its process at all. 03:40.490 --> 03:43.160 We saw that in our previous tutorial. 03:44.400 --> 03:46.260 The next one is an important point. 03:46.650 --> 03:49.740 Elections can be traversed any number of times. 03:49.950 --> 03:52.470 That is not the case with streams. 03:52.500 --> 03:54.630 It can be traversed only once. 03:54.660 --> 03:57.480 Let's take a look at an example of this one. 03:58.370 --> 04:00.650 I'm going to use the same example that we quoted. 04:02.380 --> 04:02.970 There you go. 04:02.980 --> 04:04.150 So in here. 04:05.510 --> 04:09.140 Let's say you want to iterate this collection, what do we do? 04:09.680 --> 04:10.880 We create a for loop. 04:12.120 --> 04:16.440 Spring, want to give it a name and then pass the collection. 04:16.710 --> 04:21.150 And then if we want to print all the names, we just print the name. 04:22.490 --> 04:22.870 There you go. 04:24.590 --> 04:26.690 So we printed all the names. 04:26.750 --> 04:29.240 We want to iterate the collection again. 04:29.840 --> 04:30.770 I can do that. 04:32.850 --> 04:34.410 The had printed the names again. 04:34.650 --> 04:36.760 That is not the case with streams. 04:36.780 --> 04:38.210 I'll give you an example of that. 04:38.760 --> 04:43.290 So I'm going to create a stream names, dot stream. 04:43.740 --> 04:51.150 Basically, this stream is of type collection of type list, which holds a type as string. 04:51.480 --> 04:55.620 So this is going to return me a stream of string. 04:58.690 --> 05:01.000 To name this one as name stream. 05:03.270 --> 05:05.070 And I'm going to import this. 05:05.100 --> 05:05.560 There you go. 05:05.580 --> 05:07.320 This is what it represents. 05:07.350 --> 05:14.640 Now, if I want to iterate, right, so what I'm going to do, I'm going to do name stream dot for each 05:14.910 --> 05:16.470 and I'm going to print the value. 05:17.750 --> 05:18.320 System. 05:18.320 --> 05:20.750 Dot out Colon. 05:20.750 --> 05:21.800 Colon print. 05:21.950 --> 05:25.490 Ellen I'm using the method reference syntax. 05:26.390 --> 05:29.240 So if I run this program, it's going to work. 05:29.240 --> 05:31.250 It's going to print all the results here. 05:31.310 --> 05:34.640 It's good if we want to iterate the stream again. 05:36.220 --> 05:36.760 Right. 05:36.880 --> 05:38.820 We want to do the same operation again. 05:38.830 --> 05:42.340 If I run the program, you'll be having some exception here. 05:42.370 --> 05:45.940 The exception here is Java Dot Lang. 05:45.970 --> 05:51.430 Illegal state exception stream has already been operated upon or closed. 05:51.610 --> 05:58.090 Basically you have a stream created here and with this stream you can use it only once. 05:58.090 --> 06:02.830 That's the meaning of you can only traverse the stream only once. 06:03.860 --> 06:05.390 Let's go back to the next point. 06:07.220 --> 06:15.430 It's about how iteration happens in collections and stream collections, perform external iteration 06:15.430 --> 06:17.680 to iterate through all the elements. 06:18.280 --> 06:22.620 Streams perform internal iteration to iterate through all the elements. 06:22.630 --> 06:23.680 What does it mean? 06:23.800 --> 06:31.210 So in this example, we have explicitly created this for loop and we are instructing that to iterate 06:31.210 --> 06:34.720 through the collection and print all the values in here. 06:35.410 --> 06:41.290 We didn't code anything for it, we just use the method call for each which is part of the streams API. 06:41.560 --> 06:45.010 It performs the internal iteration for you. 06:46.200 --> 06:50.870 That's the difference between the iteration, between collection and streams. 06:51.880 --> 06:56.890 So this is all the differences to remember between collections and streams. 06:57.400 --> 06:58.780 With this, we came to the end of this.