Scanner vs BufferedReader

Question

As far I know  the two most common methods of reading character-based data from a file in Java is using Scanner or BufferedReader  I also know that the BufferedReader reads files efficiently by using a buffer to avoid physical disk operations   My questions are    Does Scanner perform as well as BufferedReader  Why would you choose Scanner over BufferedReader or vice versa

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I prefer Scanner because it doesn t throw checked exceptions and therefore it s usage results in a more streamlined code

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The answer below is taken from Reading from Console  JAVA Scanner vs BufferedReader  When read an input from console  there are two options exists to achieve that  First using Scanner  another using BufferedReader  Both of them have different characteristics  It means differences how to use it   Scanner treated given input as token  BufferedReader just read line by line given input as string  Scanner it self provide parsing capabilities just like nextInt    nextFloat     But  what is others differences between    Scanner treated given input as token  BufferedReader as stream line String Scanner tokenized given input using regex  Using BufferedReader must write extra code BufferedReader faster than Scanner  point no  2 Scanner isn   t synchronized  BufferedReader synchronized   Scanner come with since JDK version 1 5 higher   When should use Scanner  or Buffered Reader   Look at the main differences between both of them  one using tokenized  others using stream line  When you need parsing capabilities  use Scanner instead  But  i am more comfortable with BufferedReader  When you need to read from a File  use BufferedReader  because it   s use buffer when read a file  Or you can use BufferedReader as input to Scanner

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BufferedReader has significantly larger buffer memory than Scanner  Use BufferedReader if you want to get long strings from a stream  and use Scanner if you want to parse specific type of token from a stream  Scanner can use tokenize using custom delimiter and parse the stream into primitive types of data  while BufferedReader can only read and store String  BufferedReader is synchronous while Scanner is not  Use BufferedReader if you re working with multiple threads  Scanner hides IOException while BufferedReader throws it immediately

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Difference between BufferedReader and Scanner are following    BufferedReader is synchronized but Scanner is not synchronized  BufferedReader is thread safe but Scanner is not thread safe  BufferedReader has larger buffer memory but Scanner has smaller buffer memory  BufferedReader is faster but Scanner is slower in execution  Code to read a line from console   BufferedReader    InputStreamReader isr new InputStreamReader System in    BufferedReader br  new BufferedReader isr    String st  br readLine      Scanner   Scanner sc  new Scanner System in   String st  sc nextLine

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BufferedReader will probably give you better performance  because Scanner is based on InputStreamReader  look sources   ups  for reading from files it uses nio  When I tested nio performance against BufferedReader performance for big files nio shows a bit better performance  For reading from file try Apache Commons IO

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Following are the differences between BufferedReader and Scanner   BufferedReader only read data but scanner also parse data  you can only read String using BufferedReader  but you can read int  long or float using Scanner  BufferedReader is older from Scanner it exists from jdk 1 1 while Scanner was added on JDK 5 release  The Buffer size of BufferedReader is large 8KB  as compared to 1KB of Scanner  BufferedReader is more suitable for reading file with long String while Scanner is more suitable for reading small user input from command prompt  BufferedReader is synchronized but Scanner is not  which means you cannot share Scanner among multiple threads  BufferedReader is faster than Scanner because it doesn t spent time on parsing BufferedReader is a bit faster as compared to Scanner BufferedReader is from java io package and Scanner is from java util package  on basis of the points we can select our choice    Thanks

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The Main Differences    Scanner      A simple text scanner which can parse primitive types and strings using regular expressions  A Scanner breaks its input into tokens using a delimiter pattern  which by default matches whitespace  The resulting tokens may then be converted into values of different types using the various next methods    Example   String input    1 fish 2 fish red fish blue fish    Scanner s   new Scanner input  useDelimiter    s fish  s      System out println s nextInt      System out println s nextInt      System out println s next      System out println s next      s close       prints the following output    1  2  red  blue    The same output can be generated with this code  which uses a regular expression to parse all four tokens at once    String input    1 fish 2 fish red fish blue fish     Scanner s   new Scanner input    s findInLine     d   fish    d   fish    w   fish    w       MatchResult result   s match     for  int i 1  i lt  result groupCount    i         System out println result group i     s close             BufferedReader    Reads text from a character-input stream  buffering characters so as to provide for the efficient reading of characters  arrays  and lines  The buffer size may be specified  or the default size may be used  The default is large enough for most purposes     In general  each read request made of a Reader causes a corresponding read request to be made of the underlying character or byte stream  It is therefore advisable to wrap a BufferedReader around any Reader whose read   operations may be costly  such as FileReaders and InputStreamReaders  For example   BufferedReader in      new BufferedReader new FileReader  foo in       will buffer the input from the specified file  Without buffering  each invocation of read   or readLine   could cause bytes to be read from the file  converted into characters  and then returned  which can be very inefficient  Programs that use DataInputStreams for textual input can be localized by replacing each DataInputStream with an appropriate BufferedReader   Source Link

User · Answer

Scanner is used for parsing tokens from the contents of the stream while BufferedReader just reads the stream and does not do any special parsing   In fact you can pass a BufferedReader to a scanner as the source of characters to parse

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In currently latest JDK6 release build  b27   the Scanner has a smaller buffer  1024 chars  as opposed to the BufferedReader  8192 chars   but it s more than sufficient   As to the choice  use the Scanner if you want to parse the file  use the BufferedReader if you want to read the file line by line  Also see the introductory text of their aforelinked API documentations    Parsing   interpreting the given input as tokens  parts   It s able to give back you specific parts directly as int  string  decimal  etc  See also all those nextXxx   methods in Scanner class   Reading   dumb streaming  It keeps giving back you all characters  which you in turn have to manually inspect if you d like to match or compose something useful  But if you don t need to do that anyway  then reading is sufficient

User · Answer

I suggest to use BufferedReader for reading text  Scanner hides IOException while BufferedReader throws it immediately

User · Answer

There are different ways of taking input in java like   1  BufferedReader 2  Scanner 3  Command Line Arguments  BufferedReader Read text from a character-input stream  buffering characters so as to provide for the efficient reading of characters  arrays  and lines   Where Scanner is a simple text scanner which can parse primitive types and strings using regular expressions   if you are writing a simple log reader Buffered reader is adequate  if you are writing an XML parser Scanner is the more natural choice   For more information please refer   http   java meritcampus com t 240 Bufferedreader tc mm69

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See this link  following is quoted from there      A BufferedReader is a simple class meant to efficiently read from the    underling stream  Generally  each read request made of a Reader like a   FileReader causes a corresponding read request to be made to   underlying stream   Each invocation of read   or readLine   could   cause bytes to be read  from the file  converted into characters  and   then returned  which can be very  inefficient  Efficiency is improved   appreciably if a Reader is warped in a  BufferedReader       BufferedReader is synchronized  so read operations on a BufferedReader   can safely be done from multiple threads       A scanner on the other hand has a lot more cheese built into it   it   can do all that a BufferedReader can do and at the same level of    efficiency as well  However  in addition a Scanner can parse  the   underlying stream for primitive types and strings using regular   expressions   It can also tokenize the underlying stream with the   delimiter of your choice   It can also do forward scanning of the   underlying stream disregarding  the delimiter       A scanner however is not thread safe  it has to be externally   synchronized       The choice of using a BufferedReader or a Scanner depends on the code    you are writing  if you are writing a simple log reader Buffered   reader  is adequate  However if you are writing an XML parser Scanner   is  the more natural choice       Even while reading the input  if want to accept user input line by   line and  say just add it to a file  a BufferedReader is good enough     On the other hand if you want to accept user input as a command with    multiple options  and then intend to perform different operations   based  on the command and options specified  a Scanner will suit   better

[java] Scanner vs. BufferedReader

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