1 00:00:01,100 --> 00:00:07,580 Let's begin with looking at the July API We will also see how it is structured and we will actually 2 00:00:07,580 --> 00:00:14,080 explore the AP on articles website Bulos or discuss a little bit about third party appeals. 3 00:00:14,300 --> 00:00:22,930 And finally we will look at a gradual sedation by an item an effective Jalla Joe IPY is a library of 4 00:00:22,940 --> 00:00:26,410 hundred softball district classes. 5 00:00:26,480 --> 00:00:34,790 Angela ate for example has over 4200 classes and these classes are read by experts like Josh Knoblock 6 00:00:35,240 --> 00:00:43,090 who's the author of effective gello book and the API is already used by millions of programmers. 7 00:00:43,420 --> 00:00:49,360 So it's really very district court and we can safely use it without having to write any of that court 8 00:00:49,390 --> 00:00:50,370 ourselves. 9 00:00:51,820 --> 00:01:01,070 On from First up don't you know that July be-I is part of both JDK and Jerry enjoy AAPI or in any professional 10 00:01:01,070 --> 00:01:07,310 product classes are grouped into something called package's packages are basically directories on the 11 00:01:07,310 --> 00:01:15,540 file system and you use a particular class you have to load a package that contains the class hit are 12 00:01:15,540 --> 00:01:21,900 some packages within the July B.A. and some of the classes they contain are shown beneath them. 13 00:01:21,900 --> 00:01:28,610 For example John Howard utl package contains classes like our analyst on Hashima later you will understand 14 00:01:28,810 --> 00:01:37,250 why packages are named in this way with multiple keywords supported by Dart's next the question is why 15 00:01:37,250 --> 00:01:45,260 do we need packages instead of providing one horrendously large pile of classes packages provide meaningful 16 00:01:45,260 --> 00:01:46,740 organization. 17 00:01:46,850 --> 00:01:51,520 Just imagine browsing through all the photos in an art classes in the July IPA. 18 00:01:51,950 --> 00:01:53,620 So it's going to be very tedious. 19 00:01:53,950 --> 00:01:58,690 So structuring them in a meaningful way based on their functionality is definitely helpful. 20 00:01:59,480 --> 00:02:03,660 For example all classes that are present because doctors are grouped into that package. 21 00:02:03,710 --> 00:02:07,850 John why don't you do so any time you are looking for a particular data structure. 22 00:02:07,880 --> 00:02:09,910 Then we can go and look in the package. 23 00:02:09,910 --> 00:02:10,780 John what are you. 24 00:02:13,070 --> 00:02:15,490 Packages also help in name scoping. 25 00:02:15,950 --> 00:02:20,380 For example Dallas has two different classes by the same name called deed. 26 00:02:20,450 --> 00:02:22,710 One is inside the package I couldn't. 27 00:02:22,900 --> 00:02:27,800 The other is inside another package called Jawad askew in little packages. 28 00:02:27,800 --> 00:02:30,380 It would not be possible to have both these classes. 29 00:02:32,570 --> 00:02:39,790 An packages also help in security for example you may want to restrict parts of your class to be inaccessible 30 00:02:39,790 --> 00:02:45,660 outside of its package that is only classes within that package should access those parts. 31 00:02:47,150 --> 00:02:55,590 Not Let's quickly look at some commonly used packages in Java IPA hostess delegate line package it includes 32 00:02:55,590 --> 00:02:58,520 classes that are fundamental to Java. 33 00:02:58,590 --> 00:03:05,960 One of the classes in this package is a stringless which we will see pretty soon next is Djala that 34 00:03:05,960 --> 00:03:12,440 you package it mainly classes representing various sophisticated instructors. 35 00:03:12,500 --> 00:03:21,430 Later we will look at different classes and this package next is your package I will hear means input 36 00:03:21,470 --> 00:03:28,230 or clauses in this package are used for doing stuff like reading from a file or writing a file. 37 00:03:29,950 --> 00:03:36,220 Next is dollar dot net package it includes classes to handle networking related to us like downloading 38 00:03:36,220 --> 00:03:44,140 a web page another commonly used one is not as your package and that's used for retrieving and storing 39 00:03:44,140 --> 00:03:46,150 data in databases. 40 00:03:46,210 --> 00:03:48,170 So these are some commonly used packages. 41 00:03:48,170 --> 00:03:54,280 And there are many more as the course progresses be learn about several classes that go into some of 42 00:03:54,280 --> 00:03:55,300 these packages. 43 00:03:56,280 --> 00:04:04,460 Not Let's go ahead and briefly explore the Java API on Oracle's Web site just go ahead and google for 44 00:04:04,460 --> 00:04:11,100 Djala eight API and just click on the first link which is hosted on Oracle's website. 45 00:04:11,120 --> 00:04:18,060 So it's the Java API documentation so this is the API documentation. 46 00:04:18,060 --> 00:04:20,990 And here there are different frames here in the top frame. 47 00:04:21,000 --> 00:04:27,460 You can see all the packages listed here are these are all the packages. 48 00:04:27,560 --> 00:04:30,100 And beneath that you can see all the classes. 49 00:04:30,230 --> 00:04:34,170 So by default it shows all the packages and all the classes. 50 00:04:34,430 --> 00:04:36,260 And here you have some description. 51 00:04:36,560 --> 00:04:39,970 So let's just go ahead and click on one of the packages. 52 00:04:40,010 --> 00:04:45,560 So here you can see a dot like package which is the R which has all the fundamental classes Angello 53 00:04:45,610 --> 00:04:47,120 that I will package. 54 00:04:47,120 --> 00:04:52,740 Now if you click on one of the packages it will show all the classes in that particular package. 55 00:04:52,970 --> 00:04:58,910 And it also shows the interfaces interfaces will be discussed later when covering object oriented concepts 56 00:04:58,910 --> 00:04:59,800 . 57 00:04:59,810 --> 00:05:04,180 So here are all the classes that you can see in Jawa dot line package. 58 00:05:04,220 --> 00:05:10,750 So let's just go ahead and click on string and Asuna also knows you play constraint class. 59 00:05:10,910 --> 00:05:15,330 You will see that all the description of the string class or here. 60 00:05:15,470 --> 00:05:18,280 So this contains all the details about the string class. 61 00:05:18,410 --> 00:05:26,340 Ok so here is the signature of the string class and some description about the string class what what 62 00:05:26,340 --> 00:05:27,670 this class does. 63 00:05:28,020 --> 00:05:32,980 And then if you scroll down you can see the fields that are used within this class. 64 00:05:33,060 --> 00:05:34,870 So this is one feat. 65 00:05:35,100 --> 00:05:42,510 And here is a summary of all the constructors so you can see that there are off constructors and stringless 66 00:05:43,230 --> 00:05:44,880 with different parameters. 67 00:05:44,880 --> 00:05:50,520 So these are all overloaded constructors and if you further scroll down it will show all the methods 68 00:05:50,520 --> 00:05:51,650 that this class has. 69 00:05:51,750 --> 00:05:58,450 OK so these are all the matters that the class has so it just gives the name of the method the method 70 00:05:58,460 --> 00:06:03,360 signatures here are and the written type on a short description about the matter. 71 00:06:03,670 --> 00:06:07,180 So same holds for all the constrictors too. 72 00:06:07,270 --> 00:06:14,430 It has a short description about each of the constructors and if you click on one of these matters so 73 00:06:14,430 --> 00:06:18,590 it gives you the all the details about that particular matter. 74 00:06:18,600 --> 00:06:18,860 OK. 75 00:06:18,870 --> 00:06:21,330 So this is the this includes the entire description. 76 00:06:21,330 --> 00:06:24,100 This is an odd description about this particular matter. 77 00:06:24,630 --> 00:06:27,310 And here is the matter signature. 78 00:06:27,390 --> 00:06:28,710 So that's the API. 79 00:06:28,710 --> 00:06:34,830 So you just browse it on you will be using a lot of this as you double up in products. 80 00:06:34,830 --> 00:06:36,950 This is what you will rely on. 81 00:06:37,050 --> 00:06:46,650 Now here that you are you can actually change this just make it 7 and it will show you the Java 7 API 82 00:06:47,070 --> 00:06:50,680 documentation you can if you change it to six it will show you that. 83 00:06:51,090 --> 00:06:53,570 So that's supported That's the API. 84 00:06:54,060 --> 00:06:58,490 And let's just head back with us Fife's on finished the rest of the lesson. 85 00:07:00,260 --> 00:07:05,770 So something looked at the July API but when we're looking professional projects you will need several 86 00:07:05,860 --> 00:07:10,710 advanced features that may not be supported by the standard July API alone. 87 00:07:11,700 --> 00:07:18,120 Luckily I was blessed with tons of third party appeals most of which are open source so you can freely 88 00:07:18,120 --> 00:07:25,580 use them and even customize them as per your needs this they're going to show the different components 89 00:07:25,730 --> 00:07:32,650 that commonly make up a complex e-commerce website the diagram also shows the third party job be ice 90 00:07:32,650 --> 00:07:32,780 . 91 00:07:32,790 --> 00:07:39,230 These components may use on the abs are shown in parenthesis for example you can see that there are 92 00:07:39,230 --> 00:07:45,850 projects like Apache Commons on Google go to and these projects include specialized libraries for using 93 00:07:45,910 --> 00:07:52,430 advanced data structures or to perform routine programming tasks like string manipulation often says 94 00:07:52,440 --> 00:07:57,950 libraries and group features that are not supported by standard July IPA or even if they're supported 95 00:07:57,950 --> 00:07:58,280 . 96 00:07:58,280 --> 00:08:02,340 These libraries may be providing more efficient alternatives. 97 00:08:02,390 --> 00:08:08,090 Google Goolwa is mostly over by Google engineers and it is very good we are not going to discuss any 98 00:08:08,090 --> 00:08:13,490 of these abs but you can look at the resources section just to learn about what these libraries have 99 00:08:13,490 --> 00:08:14,400 to offer. 100 00:08:15,990 --> 00:08:17,760 Next is it from effective Java. 101 00:08:17,810 --> 00:08:26,710 I am 47 and it says that no I use the libraries according to this item here are some benefits that good 102 00:08:26,750 --> 00:08:33,970 AP ice pro-ID focus on writing new logic without having to reinvent the wheel. 103 00:08:34,410 --> 00:08:40,380 So it's a lot of time as you don't have to write the functionality yourself and deal with any potential 104 00:08:40,380 --> 00:08:42,120 bugs that may come out of it. 105 00:08:43,940 --> 00:08:47,540 Yes also tend to improve their performance over time. 106 00:08:47,760 --> 00:08:52,860 There is performance of existing functionality would be improved in newer versions of the API. 107 00:08:54,470 --> 00:08:55,780 You you know over time. 108 00:08:55,790 --> 00:08:57,980 AP has also gained new functionality. 109 00:08:58,770 --> 00:09:04,560 So you should make yourself familiar with important parts of both standard API and also other third 110 00:09:04,560 --> 00:09:05,790 party API. 111 00:09:06,420 --> 00:09:11,970 So try to be the API documentation for all the classes to be covered in this course although we will 112 00:09:11,970 --> 00:09:14,140 cover all the important details. 113 00:09:14,640 --> 00:09:16,050 So that's about it. 114 00:09:16,050 --> 00:09:20,480 And in the next few lessons we will focus exclusively on packages. 115 00:09:20,490 --> 00:09:21,160 Thank you.