1 00:00:01,110 --> 00:00:07,530 Let's not look at how we can read and write text efficiently and the sort sort of thing here can be 2 00:00:07,530 --> 00:00:14,090 a file or a socket or even a console that is a command prompt in the follow up lessons. 3 00:00:14,120 --> 00:00:21,970 People do the most of most of the stuff we learn in this lesson let's begin with file reader unfiled 4 00:00:21,980 --> 00:00:23,430 either process. 5 00:00:23,490 --> 00:00:29,830 And as the name suggests they are used to handle files that contain text obviously files that is for 6 00:00:29,830 --> 00:00:34,780 reading characters while Filemaker is for writing got actors. 7 00:00:34,860 --> 00:00:37,060 And here is how they are instantiated. 8 00:00:37,110 --> 00:00:41,960 You simply pass a filename to their constructors. 9 00:00:41,970 --> 00:00:48,180 Earlier you said that character streams are built on top of byte streams and these classes are built 10 00:00:48,180 --> 00:00:52,110 on top of file input stream unfiled stream process. 11 00:00:52,140 --> 00:00:58,050 So internally they use these classes to do the actual reading and writing off bytes and they perform 12 00:00:58,050 --> 00:01:02,930 the necessary to and fro cancellations between bytes and characters. 13 00:01:03,990 --> 00:01:10,510 Now JVM has a default Goudeket encoding for reading and writing bytes on these classes use that encoding 14 00:01:11,540 --> 00:01:19,110 and by default JVM actually uses the default character encoding of the underlying operating system. 15 00:01:19,110 --> 00:01:23,570 I believe it is C.P 12:52 on Windows annually of 8 on Linux. 16 00:01:24,120 --> 00:01:31,170 So it is a JVM configuration and if you want to change the JVM to different encoding you can set it 17 00:01:31,170 --> 00:01:32,870 on the command line in this way. 18 00:01:33,420 --> 00:01:39,150 Here find out and coding is referred to as a system property of JVM and the option high Fundy is used 19 00:01:39,150 --> 00:01:40,840 to indicate that. 20 00:01:42,210 --> 00:01:47,910 But if you want to know what encoding your JVM uses you can use either of these two approaches. 21 00:01:47,910 --> 00:01:53,760 One is by invoking the get property method in the system class and you would have to pass a system property 22 00:01:53,760 --> 00:01:57,810 name find and encoding as a method argument. 23 00:01:57,810 --> 00:02:03,630 Second is the default Gobseck matter from the outset class which is from the Djala Dot and I package 24 00:02:03,630 --> 00:02:04,680 . 25 00:02:04,770 --> 00:02:06,540 You can check out the resources section. 26 00:02:06,570 --> 00:02:13,770 Better link is included that has more information on JVM system properties. 27 00:02:13,770 --> 00:02:19,620 Generally it is recommended not to use these classes as you have no control on the carpet and coding 28 00:02:20,540 --> 00:02:25,560 that is you're forced to use the default setting unless you use the command line option to change the 29 00:02:25,560 --> 00:02:28,590 setting so you will be platform dependent. 30 00:02:28,590 --> 00:02:35,090 If you are relying on this process so the preferred approach is to use these two classes. 31 00:02:35,210 --> 00:02:41,750 Input stream reader an output stream writer and they enable you to set the character encoding. 32 00:02:41,880 --> 00:02:47,910 Well if I later unfiled order were specific to files these are general purpose classes for doing the 33 00:02:47,910 --> 00:02:50,970 translations between byte and Carkner streams. 34 00:02:51,430 --> 00:02:56,940 And hence you can see that the input parameters of the constructors of the abstract input stream an 35 00:02:57,000 --> 00:03:04,020 output stream process that is not specific to file streams and hence can be passed any by stream objects 36 00:03:05,340 --> 00:03:08,110 so input stream reader will translate from bytes. 37 00:03:08,100 --> 00:03:13,590 Look at occurs while output stream writer would translate from characters to bytes. 38 00:03:14,190 --> 00:03:19,310 So the benefit of using these two classes is that they are general purpose on modeler. 39 00:03:19,350 --> 00:03:23,220 You can set the carpet encoding off your choice. 40 00:03:23,250 --> 00:03:28,060 There are also overloaded constrictors and you can check them out from the API. 41 00:03:28,920 --> 00:03:30,570 And here is an example. 42 00:03:30,570 --> 00:03:33,290 Here we want to read on benzyl for text file. 43 00:03:33,750 --> 00:03:38,910 So you must create a file input stream object and then we pass it as an argument to the input stream 44 00:03:38,910 --> 00:03:39,820 reader. 45 00:03:40,050 --> 00:03:44,500 Here the character encoding is specified as Eudy of eight. 46 00:03:45,510 --> 00:03:51,930 Since files are on Filemaker are specific to files they actually extend these classes as these classes 47 00:03:51,930 --> 00:03:53,930 are more generic. 48 00:03:54,000 --> 00:04:01,890 Also note is that I do here says Michie's and that's because these classes act as a bridge in the translation 49 00:04:01,890 --> 00:04:09,690 between bytes and characters and to achieve Dopp efficiency you would grab them with that buffered reader 50 00:04:09,780 --> 00:04:15,600 or buffer the writer class which provide additional buffering capability. 51 00:04:15,630 --> 00:04:19,100 And here are the constructors for buffered reader and buffer writer. 52 00:04:19,170 --> 00:04:22,730 They simply take out after streams reader and writers input. 53 00:04:23,040 --> 00:04:30,050 There are also overloaded versions which additionally take the buffer size of them but note that the 54 00:04:30,050 --> 00:04:33,820 default buffer size is around 8000 characters. 55 00:04:33,900 --> 00:04:41,370 That is it is a Carrere with the size of add on 8000 So these are similar to buffer input stream unbuffered 56 00:04:41,430 --> 00:04:49,190 output stream process which are chained to input stream an output stream instances So let's look at 57 00:04:49,190 --> 00:04:53,320 the Bufford reader on here and read methods written before Twitter. 58 00:04:53,550 --> 00:04:56,900 We all get it is because of too while discussing Rueter. 59 00:04:57,170 --> 00:05:02,320 However we now get the additional benefit of buffering just method here. 60 00:05:02,320 --> 00:05:03,930 Returns a single character. 61 00:05:04,190 --> 00:05:10,580 Well the second one reads a group of characters in the input katak it underlines that amount of character 62 00:05:10,580 --> 00:05:18,410 Selecta Turbin is something new and it is probably the most commonly used when reading Cocker's as a 63 00:05:18,410 --> 00:05:19,600 matter of or. 64 00:05:19,700 --> 00:05:24,530 It simply needs a single line of text unrepented as a string. 65 00:05:24,530 --> 00:05:30,230 So if the input character stream has spects with several lines then this method can read on each line 66 00:05:30,230 --> 00:05:31,180 separately. 67 00:05:31,580 --> 00:05:37,970 That is each invocation rodent's one single line and to identify lines. 68 00:05:38,270 --> 00:05:44,270 The matter looks what these lines up added or as a line feed a carriage return or a carriage return 69 00:05:44,270 --> 00:05:47,780 followed immediately by a line feed. 70 00:05:47,780 --> 00:05:53,960 Also just in case if you are not aware of this line separate or guns they happen to come from the typewriter 71 00:05:53,960 --> 00:06:00,800 times where carriage return would signal moving horizontally to the beginning of the same line one line 72 00:06:00,800 --> 00:06:04,140 feet would signal moving to the next line. 73 00:06:04,380 --> 00:06:10,040 So together they give you the effect of moving to the beginning of the next line. 74 00:06:10,300 --> 00:06:16,170 And here is an example of using a buffered reader for reading a text file which is named as go doc. 75 00:06:16,190 --> 00:06:17,530 The XTi. 76 00:06:17,570 --> 00:06:18,930 So the Cripe answers. 77 00:06:18,950 --> 00:06:20,490 We help buffer the reader. 78 00:06:20,600 --> 00:06:26,630 Just change to an input stream reader that is intention to file input stream which actually reached 79 00:06:26,630 --> 00:06:28,010 bytes from the file. 80 00:06:28,520 --> 00:06:31,370 So that's three objects chained together. 81 00:06:31,370 --> 00:06:37,790 So file input stream reef's bytes from the file while input stream leader translates those bytes into 82 00:06:37,790 --> 00:06:44,990 characters using UAP of 8 encoding and finally buffer reader would buffer those characters so that we 83 00:06:44,990 --> 00:06:47,380 get the performance benefit. 84 00:06:47,690 --> 00:06:53,810 Outside that block we are creating a string builder that is used for accumulating that text read from 85 00:06:53,810 --> 00:06:54,750 the file. 86 00:06:55,430 --> 00:07:01,610 So the while loop with each iteration reads a single line of text and we can see that it is using the 87 00:07:01,610 --> 00:07:09,170 read line method of the buffer reader object and with each iteration the line that is read is appended 88 00:07:09,170 --> 00:07:11,710 to the string builder object. 89 00:07:11,720 --> 00:07:18,290 Also notice that we are opening a new line explicitly and that's because Red Line method strips new 90 00:07:18,290 --> 00:07:19,620 lines. 91 00:07:19,670 --> 00:07:26,690 Finally once the entire text is read the relend method were written in and the loop terminated. 92 00:07:26,980 --> 00:07:31,550 And finally we can do it on the string containing the string builder. 93 00:07:31,560 --> 00:07:38,000 Also please make sure we use cringle for such cases as using Pless for concatenation would be very expensive 94 00:07:38,010 --> 00:07:38,620 . 95 00:07:38,940 --> 00:07:46,580 And if the file is very large then it may involve several concatenation operations on here as an example 96 00:07:46,630 --> 00:07:50,130 rendered rendering text from a console that has a command prompt. 97 00:07:50,370 --> 00:07:56,310 Only change here is in the Cripe parenthesis file input stream has been replaced with System Duggin 98 00:07:57,250 --> 00:08:04,430 in is basically a static variable within the system class and it represents an input stream object and 99 00:08:04,430 --> 00:08:09,830 we know that input stream reader is a general purpose bridge class and so it can work with any input 100 00:08:09,830 --> 00:08:15,920 stream object and the text that the user enters in the console will be captured by the read line method 101 00:08:15,920 --> 00:08:16,820 . 102 00:08:16,850 --> 00:08:23,000 So in this case the user will be repeatedly prompted for input on the news user and does the text start 103 00:08:23,630 --> 00:08:27,970 at which point the while loop will terminate. 104 00:08:28,130 --> 00:08:30,860 So we look at how we can read dextro efficiently. 105 00:08:30,860 --> 00:08:33,960 Now let's see how we can write extra efficiently. 106 00:08:34,280 --> 00:08:40,340 Here's an example of using a buffered writer for writing a text file unchaining is very similar to the 107 00:08:40,340 --> 00:08:43,470 read operation in the type parenthesis. 108 00:08:43,580 --> 00:08:49,550 We have a buffered writer that just change to an output stream loader that is in turn change the final 109 00:08:49,550 --> 00:08:56,770 output stream which writes bytes to the destination fine character encoding used for writing bytes is 110 00:08:56,790 --> 00:09:03,520 UTF aid here write methods and work on the buffer to write an object with some text pass doesn't boot 111 00:09:03,530 --> 00:09:04,060 . 112 00:09:04,730 --> 00:09:08,840 You can assume it has a string but it can also be a character in it. 113 00:09:08,930 --> 00:09:13,030 And it means that right is an overloaded method. 114 00:09:13,040 --> 00:09:17,930 In fact this notion of the right method is actually inherited from the writer class. 115 00:09:18,230 --> 00:09:22,510 You can take a look at the API of this class to get more understanding of it. 116 00:09:23,060 --> 00:09:28,280 So that's about it will get Halvard can't read dextro efficiently from an input stream. 117 00:09:28,370 --> 00:09:32,790 And also how we can write text efficiently to some output stream. 118 00:09:32,840 --> 00:09:37,850 Next we are willing to do one AACo the most good test all the stuff we learned in this lesson. 119 00:09:38,060 --> 00:09:38,470 Thank you