Java Reference
In-Depth Information
ited with single quotes. XPath provides the
=
and
!=
operators for comparing strings.
XPathalsopredefinesthe
string()
functiontoconvertitsargumenttoastring,
con-
cat()
to return a concatenation of its string arguments,
starts-with()
to return
true when the first argument string starts with the second argument string (and other-
wisereturnsfalse),
contains()
toreturntruewhenthefirstargumentstringcontains
thesecondargumentstring(andotherwisereturnsfalse),
substring-before()
to
returnthesubstringofthefirstargumentstringthatprecedesthefirstoccurrenceofthe
second argument string in the first argument string, or the empty string when the first
argumentstringdoesnotcontainthesecondargumentstring,
substring-after()
toreturnthesubstringofthefirstargumentstringthatfollowsthefirstoccurrenceofthe
second argument string in the first argument string, or the empty string when the first
argumentstringdoesnotcontainthesecondargumentstring,
substring()
toreturn
thesubstringofthefirst(string)argumentstartingatthepositionspecifiedinthesecond
(number) argument with length specified in the third (number) argument,
string-
length()
toreturnthenumberofcharactersinitsstringargument(orthelengthofthe
contextnodewhenconvertedtoastringintheabsenceofanargument),
normalize-
space()
toreturntheargumentstringwithwhitespacenormalizedbystrippinglead-
ingandtrailingwhitespaceandreplacingsequencesofwhitespacecharactersbyasingle
space (or performing the same action on the context node when converted to a string
intheabsenceofanargument),and
translate()
toreturnthefirstargumentstring
withoccurrencesofcharactersinthesecondargumentstringreplacedbythecharacter
at the corresponding position in the third argument string.
Finally,XPathpredefinesseveralfunctionsforusewithnodesets:
last()
returnsa
numberidentifyingthelastnode,
position()
returnsanumberidentifyinganode's
position,
count()
returnsthenumberofnodesinitsnodesetargument,
id()
selects
elementsbytheiruniqueIDsandreturnsanodesetoftheseelements,
local-name()
returns the local part of the qualified name of the first node in its nodeset argument,
namespace-uri()
returnsthenamespacepartofthequalifiednameofthefirstnode
initsnodesetargument,and
name()
returnsthequalifiednameofthefirstnodeinits
nodeset argument.
XPath and DOM
Suppose you need someone in your home to purchase a bag of sugar. You can tell
thispersonto“Pleasebuymesomesugar.”Alternatively,youcouldsaythefollowing:
“Pleaseopenthefrontdoor.Walkdowntothesidewalk.Turnleft.Walkupthesidewalk
for three blocks. Turn right. Walk up the sidewalk one block. Enter the store. Go to
