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BufferedReader/Writer
Posted on: July 26, 2006 at 12:00 AM

java.io.BufferedReader and java.io.BufferedWriter are used to read/write Strings from/to text files.

Java Notes

BufferedReader/Writer

Example code of BufferedReader and BufferedWriter class in Java. In this example code you will learn how to use these classes to perform basic read and write operations.

Java BufferedReader class is used to read the data in buffer.

The BufferedWriter class is used for buffered writing writing of data.

`BufferedReader` and `BufferedWriter` methods

java.io.BufferedReader and java.io.BufferedWriter are used to read/write Strings from/to text files.

Assume

BufferedReader br;
BufferedWriter bw;
File f;
char[] ca;
String s;
int c;         // This is an int to hold either a char or -1.
int offset, len, size;

BufferedReader

BufferedReader Constructor -- see examples
br =	new BufferedReader(new FileReader(f));
BufferedReader Methods
s =	br.readLine()	Returns next input line without newline char(s) or null if no more input. May throw IOException.
c =	br.read()	Reads and returns one char. Returns -1 on end-of-file. Note that that this returns an `int`, which is necessary so that the -1 value indicating EOF can be stored. The int value can be cast to a char. May throw IOException.
size =	br.read(ca, offset, len)	Read up to len chars into ca starting at index offset. Returns -1 on end-of-file. May throw IOException.
	br.close()	Close when finished reading to unlock file.

BufferedWriter

BufferedWriter Constructor -- see examples
bw =	new BufferedWriter(new FileWriter(f));
BufferedWriter Methods
	bw.write(s, offset, len)	Writes len chars from s starting at index offset. May throw IOException.
	bw.write(ca, offset, len)	Writes len chars from ca starting at index offset. May throw IOException.
	bw.write(s)	Writes s to file. Doesn't add newline char. May throw IOException.
	bw.write(c)	Writes single character c to file. May throw IOException.
	bw.newLine()	Writes operating-system dependent newline (CR, LF, or CRLF).
	bw.close()	Call `close()` when finished writing, otherwise data may not be written to disk.

Example

See File I/O - Text Files for an example of reading and writing text files.

Copyleft 2005 Fred Swartz MIT License

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