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BufferedReaderCheat.java
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73 lines (58 loc) · 2.18 KB
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/*
# BufferedReader
Automagically prefetches reads larger chunks than immediately required.
Faster than a non-buffered reader if you are going to read the whole file anyways.
http://docs.oracle.com/javase/7/docs/api/java/io/BufferedReader.html
Is itself a reader, and simply acts as a wraper around another `Reader`:
http://docs.oracle.com/javase/7/docs/api/java/io/Reader.html
The most common reader to use wrap around is `FileReader`.
*/
import java.io.BufferedReader;
import java.io.StringReader;
import java.io.IOException;
public class BufferedReaderCheat {
public static void main(String[] args) {
/*
# Read file line-by-line
# readLine
A line is considered to be terminated by any one of a line feed ('\n'),
a carriage return ('\r'), or a carriage return followed immediately by a linefeed.
Using BufferedReader + FileReader is the most common combo.
Readers must be used instead of the stream because this operation
is encoding dependant.
*/
{
BufferedReader br = new BufferedReader(new StringReader("ab\ncd\n"));
try {
assert(br.readLine().equals("ab"));
assert(br.readLine().equals("cd"));
assert(br.readLine() == null);
} catch (IOException e) {}
// Loop usage.
{
// Good method: line has small scope.
/*
for (String line; (line = br.readLine()) != null;) {
// line
}
*/
// Saner version.
/*
String line = null;
do {
line = br.readLine();
} while (line != null);
*/
// Another possibility.
/*
String line;
while ((line = br.readLine()) != null) {}
*/
}
/*
Check if reader is at EOF: not possible without reading.
http://stackoverflow.com/questions/3714090/how-to-see-if-a-reader-is-at-eof
*/
}
}
}