Can anyone explain me the difference between the class BufferedReader
, FileReader
and Scanner
? and which one to use when I want to read a text file?
Scanner and BufferReader both classes are used to read input from external system. Scanner is normally used when we know input is of type string or of primitive types and BufferReader is used to read text from character streams while buffering the characters for efficient reading of characters.
BufferedReader is a bit faster as compared to scanner because scanner does parsing of input data and BufferedReader simply reads sequence of characters.
The main difference between BufferedReader and BufferedInputStream is that BufferedReader reads characters (text), whereas the BufferedInputStream reads raw bytes. The Java BufferedReader class is a subclass of the Java Reader class, so you can use a BufferedReader anywhere a Reader is required.
BufferedReader reads a couple of characters from the Input Stream and stores them in a buffer. InputStreamReader reads only one character from the input stream and the remaining characters still remain in the streams hence There is no buffer in this case.
Well:
FileReader
is just a Reader
which reads a file, using the platform-default encoding (urgh)BufferedReader
is a wrapper around another Reader
, adding buffering and the ability to read a line at a timeScanner
reads from a variety of different sources, but is typically used for interactive input. Personally I find the API of Scanner
to be pretty painful and obscure.To read a text file, I would suggest using a FileInputStream
wrapped in an InputStreamReader
(so you can specify the encoding) and then wrapped in a BufferedReader
for buffering and the ability to read a line at a time.
Alternatively, you could use a third-party library which makes it simpler, such as Guava:
File file = new File("foo.txt");
List<String> lines = Files.readLines(file, Charsets.UTF_8);
Or if you're using Java 7, it's already available for you in java.nio.file.Files
:
Path path = FileSystems.getDefault().getPath("foo.txt");
List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
And as per your question for reading a text file you should use BufferedReader
because Scanner
hides IOException while BufferedReader
throws it immediately.
BufferedReader
is synchronized and Scanner
is not.
Scanner
is used for parsing tokens from the contents of the stream.
BufferedReader
just reads the stream.
For more info follow the link (http://en.allexperts.com/q/Java-1046/2009/2/Difference-Scanner-Method-Buffered.htm)
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