Java Notes

BufferedReader/Writer

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.