Java Reference
In-Depth Information
}
return false;
}
}
methods.
main()
validatesthenumberofcommand-linearguments,whichmustbetwo.The
firstargumentidentifiesthestartinglocationwithinthefilesystemforthesearch,andis
used to construct a
File
object. The second argument specifies search text.
main()
thenpassesthe
File
objectandthesearchtextto
findAll()
toperformasearchfor
all files containing this text.
The recursive
findAll()
method first invokes
listFiles()
on the
File
ob-
ject passed to this method, to obtain the names of all files in the current directory. If
listFiles()
returnsnull,meaningthatthe
File
objectdoesn'trefertoanexisting
directory,
findAll()
returns false and a suitable error message is output.
Foreachnameinthereturnedlist,
findAll()
eitherrecursivelyinvokesitselfwhen
thenamerepresentsadirectory,orinvokesthe
find()
methodtosearchthefileforthe
text; the file's pathname string is output when the file contains this text.
The
find()
method first opens the file identified by its first argument via the
FileReader
class, and then passes the
FileReader
instance to a
BufferedReader
instancetoimprovefile-readingperformance.Itthenentersaloop
that continues to read characters from the file until the end of the file is reached.
Ifthecurrentlyreadcharactermatchesthefirstcharacterinthesearchtext,aninner
loopisenteredtoreadsubsequentcharactersfromthefileandcomparethemwithsub-
sequentcharactersinthesearchtext.Whenallcharactersmatch,
find()
returnstrue.
Otherwise,thelabeledcontinuestatementisusedtoskiptheremainingiterationsofthe
innerloopandtransferexecutiontothelabeledouterloop.Afterthelastcharacterhas
been read and there's still no match,
find()
returns false.
Nowthatyouknowhow
FindAll
works,you'llprobablywanttotryitout.Thefol-
lowing examples show you how I might use this application on my XP platform:
java FindAll \prj\dev OpenGL
Thisexamplesearchesthe
\prj\dev
directoryonmydefaultdrive(C:)forallfiles
that contain the word
OpenGL
(case is significant) and generates the following output:
