joshua.util.io.LineReader Class Reference

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List of all members.

Public Member Functions
	LineReader (String filename) throws IOException
	LineReader (InputStream in)
	LineReader (BufferedReader reader)
void	close () throws IOException
boolean	ready () throws IOException
String	readLine () throws IOException
Iterator< String >	iterator ()
boolean	hasNext ()
String	next () throws NoSuchElementException
void	remove () throws UnsupportedOperationException
int	countLines () throws IOException
Static Public Member Functions
static final InputStream	getInputStream (String filename) throws IOException
static void	main (String[] args)
Protected Member Functions
void	finalize () throws Throwable
Private Attributes
BufferedReader	reader
String	buffer
IOException	error
Static Private Attributes
static final Charset	FILE_ENCODING = Charset.forName("UTF-8")

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Detailed Description

This class provides an Iterator interface to a BufferedReader. This covers the most common use-cases for reading from files without ugly code to check whether we got a line or not.

Author:

wren ng thornton wren@.nosp@m.user.nosp@m.s.sou.nosp@m.rcef.nosp@m.orge..nosp@m.net

Version:

LastChangedDate:

2009-03-26 15:06:57 -0400 (Thu, 26 Mar 2009)

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Constructor & Destructor Documentation

joshua.util.io.LineReader.LineReader

(

String

filename

)

throws IOException

Opens a file for iterating line by line. If the file name ends in ".gz" then we automatically open it with GZIP. File encoding is assumed to be UTF-8.

Parameters:

filename

the file to be opened

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joshua.util.io.LineReader.LineReader

(

InputStream

in

)

Wraps an InputStream for iterating line by line. Stream encoding is assumed to be UTF-8.

joshua.util.io.LineReader.LineReader

(

BufferedReader

reader

)

Uses a BufferedReader for iterating line by line.

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Member Function Documentation

void joshua.util.io.LineReader.close

(

)

throws IOException

This method will close the file handle, and will raise any exceptions that occured during iteration. The method is idempotent, and all calls after the first are no-ops (unless the thread was interrupted or killed). For correctness, you must call this method before the object falls out of scope.

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int joshua.util.io.LineReader.countLines

(

)

throws IOException

Iterates over all lines, ignoring their contents, and returns the count of lines. If some lines have already been read, this will return the count of remaining lines. Because no lines will remain after calling this method, we implicitly call close.

Returns:

the number of lines read

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void joshua.util.io.LineReader.finalize

(

)

throws Throwable [protected]

We attempt to avoid leaking file descriptors if you fail to call close before the object falls out of scope. However, the language spec makes no guarantees about timeliness of garbage collection. It is a bug to rely on this method to release the resources. Also, the garbage collector will discard any exceptions that have queued up, without notifying the application in any way.

Having a finalizer means the JVM can't do "fast allocation" of LineReader objects (or subclasses). This isn't too important due to disk latency, but may be worth noting.

See also:

Performance Tips

Techniques

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static final InputStream joshua.util.io.LineReader.getInputStream

(

String

filename

)

throws IOException [static]

Returns an InputStream for a filename, using Joshua's canonical means for interpreting that name (e.g\ detecting gzipped files). This is used by the LineReader constructor that accepts a String argument.

Deprecated:

This method is provided in order for joshua.decoder.DecoderThread to open files in the canonical way for handing off to joshua.decoder.segment_file.SegmentFileParser. The SegmentFileParser interface can't be made more liberal (e.g. to accept a java.io.Reader) because javax.xml.parsers.SAXParser can't parse that argument and no common java.io.Reader gives access to the underlying InputStream. This method is considered a hack which should be removed once a better solution presents itself.

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boolean joshua.util.io.LineReader.hasNext

(

)

Returns true if the iteration has more elements. (In other words, returns true if next would return an element rather than throwing an exception.)

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Iterator<String> joshua.util.io.LineReader.iterator

(

)

Return self as an iterator.

static void joshua.util.io.LineReader.main

(

String[]

args

)

[static]

Example usage code.

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String joshua.util.io.LineReader.next

(

)

throws NoSuchElementException

Return the next line of the file. If an error is encountered, NoSuchElementException is thrown. The actual IOException encountered will be thrown later, when the LineReader is closed. Also if there is no line to be read then NoSuchElementException is thrown.

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String joshua.util.io.LineReader.readLine

(

)

throws IOException

This method is like next() except that it throws the IOException directly. If there are no lines to be read then null is returned.

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boolean joshua.util.io.LineReader.ready

(

)

throws IOException

Determine if the reader is ready to read a line.

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void joshua.util.io.LineReader.remove

(

)

throws UnsupportedOperationException

Unsupported.

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Member Data Documentation

String joshua.util.io.LineReader.buffer [private]

IOException joshua.util.io.LineReader.error [private]

final Charset joshua.util.io.LineReader.FILE_ENCODING = Charset.forName("UTF-8") [static, private]

BufferedReader joshua.util.io.LineReader.reader [private]