Class FileCorrector

java.lang.Object

Corrector

FileCorrector

public class FileCorrector
extends Corrector

A Corrector whose spelling suggestions are given in a text file.

One way to get corrections for a misspelled word is to consult an external resource. This kind of Corrector uses a file that contains pairs of words on each line (a misspelled word and a correction for that misspelling) to generate corrections.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FileCorrector.FormatException A special purpose exception class to indicate errors when reading the input for the FileCorrector.

Constructor Summary

Constructors

Constructor and Description
FileCorrector(java.io.Reader r) Constructs a FileCorrector from the argued Reader.

Method Summary

Methods

Modifier and Type	Method and Description
java.util.Set<java.lang.String>	getCorrections(java.lang.String wrong) Returns a set of proposed corrections for an incorrectly spelled word.
static FileCorrector	make(java.lang.String filename) Constructs a FileCorrecotr from a file.

Methods inherited from class Corrector

matchCase

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FileCorrector

public FileCorrector(java.io.Reader r)
              throws java.io.IOException,
                     FileCorrector.FormatException

Constructs a FileCorrector from the argued Reader. Instead of using the TokenScanner to parse this input, you should read the input line by line using a BufferedReader. This way you will practice with an alternative approach to working with text. For methods useful in parsing the lines of the file, see the String class javadocs in java.lang.String

Each line in the input should have a single comma that separates two parts in the form: misspelled_word,corrected_version

For example:

 aligatur,alligator

 baloon,balloon

 inspite,in spite

 who'ev,who've

 ther,their

 ther,there

 

The lines are not case-sensitive, so all of the following lines should function equivalently:

 baloon,balloon

 Baloon,balloon

 Baloon,Balloon

 BALOON,balloon

 bAlOon,BALLOON

 

You should ignore any leading or trailing whitespace around the misspelled and corrected parts of each line. Thus, the following lines should all be equivalent:

 inspite,in spite

    inspite,in spite

 inspite   ,in spite

  inspite ,   in spite  

 

Note that spaces are allowed inside the corrected word. (In general, the FileCorrector is allowed to suggest Strings that are not words according to TokenScanner.)

You should throw a FileCorrector.FormatException if you encounter input that is invalid. For example, the FileCorrector constructor should throw an exception if any of these inputs are encountered:

 ,correct

 wrong,

 wrong correct

 wrong,correct,

 

Parameters:

r - The sequence of characters to parse

Throws:

java.io.IOException - If error while reading

FileCorrector.FormatException - If an invalid line is encountered

java.lang.IllegalArgumentException - If the provided reader is null

Method Detail

make

public static FileCorrector make(java.lang.String filename)
                          throws java.io.IOException,
                                 FileCorrector.FormatException

Constructs a FileCorrecotr from a file.

Parameters:

filename - Location of file from which to read

Returns:

A FileCorrector with corrections from the argued file

Throws:

java.io.FileNotFoundException - If the file does not exist

java.io.IOException - If error while reading

FileCorrector.FormatException - If an invalid line is encountered

getCorrections

public java.util.Set<java.lang.String> getCorrections(java.lang.String wrong)

Returns a set of proposed corrections for an incorrectly spelled word. The corrections should match the case of the input; the matchCase method is helpful here.

For any input that is *not* a valid word, throw an IllegalArgumentException. A valid word is any sequence of letters (as determined by Character.isLetter) or apostrophes characters.

Specified by:

getCorrections in class Corrector

Parameters:

wrong - The misspelled word

Returns:

A (potentially empty) set of proposed corrections

Throws:

java.lang.IllegalArgumentException - If the input is not a valid word (i.e. not composed of only letters and/or apostrophes)