public
abstract
class
SearchIterator
extends Object
| java.lang.Object | |
| ↳ | android.icu.text.SearchIterator |
 Known Direct Subclasses
|
SearchIterator is an abstract base class that provides methods to search for a pattern within a text string. Instances of SearchIterator maintain a current position and scan over the target text, returning the indices the pattern is matched and the length of each match.
SearchIterator defines a protocol for text searching. Subclasses provide concrete implementations of various search algorithms. For example, StringSearch implements language-sensitive pattern matching based on the comparison rules defined in a RuleBasedCollator object.
Other options for searching include using a BreakIterator to restrict the points at which matches are detected.
SearchIterator provides an API that is similar to that of other text iteration classes such as BreakIterator. Using this class, it is easy to scan through text looking for all occurrences of a given pattern. The following example uses a StringSearch object to find all instances of "fox" in the target string. Any other subclass of SearchIterator can be used in an identical manner.
Developers
String target = "The quick brown fox jumped over the lazy fox";
String pattern = "fox";
SearchIterator iter = new StringSearch(pattern, target);
for (int pos = iter.first(); pos != SearchIterator.DONE;
pos = iter.next()) {
System.out.println("Found match at " + pos +
", length is " + iter.getMatchLength());
}
See also:
Nested classes | |
|---|---|
enum |
SearchIterator.ElementComparisonType
Option to control how collation elements are compared. |
Constants | |
|---|---|
int |
DONE
DONE is returned by previous() and next() after all valid matches have been returned, and by first() and last() if there are no matches at all. |
Fields | |
|---|---|
protected
BreakIterator |
breakIterator
The BreakIterator to define the boundaries of a logical match. |
protected
int |
matchLength
Length of the most current match in target text. |
protected
CharacterIterator |
targetText
Target text for searching. |
Protected constructors | |
|---|---|
SearchIterator(CharacterIterator target, BreakIterator breaker)
Protected constructor for use by subclasses. |
|
Public methods | |
|---|---|
final
int
|
first()
Returns the first index at which the string text matches the search pattern. |
final
int
|
following(int position)
Returns the first index equal or greater than position at which the string text matches the search pattern. |
BreakIterator
|
getBreakIterator()
Returns the BreakIterator that is used to restrict the indexes at which matches are detected. |
SearchIterator.ElementComparisonType
|
getElementComparisonType()
Returns the collation element comparison type. |
abstract
int
|
getIndex()
Return the current index in the text being searched. |
int
|
getMatchLength()
Returns the length of text in the string which matches the search pattern. |
int
|
getMatchStart()
Returns the index to the match in the text string that was searched. |
String
|
getMatchedText()
Returns the text that was matched by the most recent call to
|
CharacterIterator
|
getTarget()
Return the string text to be searched. |
boolean
|
isOverlapping()
Return true if the overlapping property has been set. |
final
int
|
last()
Returns the last index in the target text at which it matches the search pattern. |
int
|
next()
Returns the index of the next point at which the text matches the
search pattern, starting from the current position
The iterator is adjusted so that its current index (as returned by
|
final
int
|
preceding(int position)
Returns the first index less than position at which the string text matches the search pattern. |
int
|
previous()
Returns the index of the previous point at which the string text matches the search pattern, starting at the current position. |
void
|
reset()
Resets the iteration. |
void
|
setBreakIterator(BreakIterator breakiter)
Set the BreakIterator that will be used to restrict the points at which matches are detected. |
void
|
setElementComparisonType(SearchIterator.ElementComparisonType type)
Sets the collation element comparison type. |
void
|
setIndex(int position)
Sets the position in the target text at which the next search will start. |
void
|
setOverlapping(boolean allowOverlap)
Determines whether overlapping matches are returned. |
void
|
setTarget(CharacterIterator text)
Set the target text to be searched. |
Protected methods | |
|---|---|
abstract
int
|
handleNext(int start)
Abstract method which subclasses override to provide the mechanism for finding the next match in the target text. |
abstract
int
|
handlePrevious(int startAt)
Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text. |
void
|
setMatchLength(int length)
Sets the length of the most recent match in the target text. |
Inherited methods | |
|---|---|
From
class
java.lang.Object
| |
int DONE
DONE is returned by previous() and next() after all valid matches have been returned, and by first() and last() if there are no matches at all.
See also:
Constant Value: -1 (0xffffffff)
BreakIterator breakIterator
The BreakIterator to define the boundaries of a logical match. This value can be a null. See class documentation for more information.
int matchLength
Length of the most current match in target text. Value 0 is the default value.
See also:
SearchIterator (CharacterIterator target, BreakIterator breaker)
Protected constructor for use by subclasses.
Initializes the iterator with the argument target text for searching
and sets the BreakIterator.
See class documentation for more details on the use of the target text
and BreakIterator.
| Parameters | |
|---|---|
target |
CharacterIterator:
The target text to be searched. |
breaker |
BreakIterator:
A BreakIterator that is used to determine the
boundaries of a logical match. This argument can be null. |
| Throws | |
|---|---|
IllegalArgumentException |
thrown when argument target is null, or of length 0 |
See also:
int first ()
Returns the first index at which the string text matches the search
pattern. The iterator is adjusted so that its current index (as
returned by getIndex()) is the match position if one
was found.
If a match is not found, DONE will be returned and
the iterator will be adjusted to the index DONE.
| Returns | |
|---|---|
int |
The character index of the first match, or
DONE if there are no matches. |
See also:
int following (int position)
Returns the first index equal or greater than position at which the
string text matches the search pattern. The iterator is adjusted so
that its current index (as returned by getIndex()) is the
match position if one was found.
If a match is not found, DONE will be returned and the
iterator will be adjusted to the index DONE.
| Parameters | |
|---|---|
position |
int:
where search if to start from. |
| Returns | |
|---|---|
int |
The character index of the first match following
position, or DONE if there are no matches. |
| Throws | |
|---|---|
IndexOutOfBoundsException |
If position is less than or greater than the text range for searching. |
See also:
BreakIterator getBreakIterator ()
Returns the BreakIterator that is used to restrict the indexes at which
matches are detected. This will be the same object that was passed to
the constructor or to setBreakIterator(BreakIterator).
If the BreakIterator has not been set, null will be returned.
See setBreakIterator(BreakIterator) for more information.
| Returns | |
|---|---|
BreakIterator |
the BreakIterator set to restrict logic matches |
SearchIterator.ElementComparisonType getElementComparisonType ()
Returns the collation element comparison type.
| Returns | |
|---|---|
SearchIterator.ElementComparisonType |
|
int getIndex ()
Return the current index in the text being searched.
If the iteration has gone past the end of the text
(or past the beginning for a backwards search), DONE
is returned.
| Returns | |
|---|---|
int |
current index in the text being searched. |
int getMatchLength ()
Returns the length of text in the string which matches the search
pattern. This call returns a valid result only after a successful call
to first(), next(), previous(), or last().
Just after construction, or after a searching method returns
DONE, this method will return 0.
| Returns | |
|---|---|
int |
The length of the match in the target text, or 0 if there is no match currently. |
See also:
int getMatchStart ()
Returns the index to the match in the text string that was searched.
This call returns a valid result only after a successful call to
first(), next(), previous(), or last().
Just after construction, or after a searching method returns
DONE, this method will return DONE.
Use getMatchLength() to get the matched string length.
| Returns | |
|---|---|
int |
index of a substring within the text string that is being searched. |
See also:
String getMatchedText ()
Returns the text that was matched by the most recent call to
first(), next(), previous(), or last().
If the iterator is not pointing at a valid match (e.g. just after
construction or after DONE has been returned,
returns an empty string.
| Returns | |
|---|---|
String |
the substring in the target test of the most recent match, or null if there is no match currently. |
See also:
CharacterIterator getTarget ()
Return the string text to be searched.
| Returns | |
|---|---|
CharacterIterator |
text string to be searched. |
boolean isOverlapping ()
Return true if the overlapping property has been set.
See setOverlapping(boolean) for more information.
| Returns | |
|---|---|
boolean |
true if the overlapping property has been set, false otherwise |
See also:
int last ()
Returns the last index in the target text at which it matches the
search pattern. The iterator is adjusted so that its current index
(as returned by getIndex()) is the match position if one was
found.
If a match is not found, DONE will be returned and
the iterator will be adjusted to the index DONE.
| Returns | |
|---|---|
int |
The index of the first match, or DONE if
there are no matches. |
See also:
int next ()
Returns the index of the next point at which the text matches the
search pattern, starting from the current position
The iterator is adjusted so that its current index (as returned by
getIndex()) is the match position if one was found.
If a match is not found, DONE will be returned and
the iterator will be adjusted to a position after the end of the text
string.
| Returns | |
|---|---|
int |
The index of the next match after the current position,
or DONE if there are no more matches. |
See also:
int preceding (int position)
Returns the first index less than position at which the string
text matches the search pattern. The iterator is adjusted so that its
current index (as returned by getIndex()) is the match
position if one was found. If a match is not found,
DONE will be returned and the iterator will be
adjusted to the index DONE
When the overlapping option (isOverlapping()) is off, the last index of the
result match is always less than position.
When the overlapping option is on, the result match may span across
position.
| Parameters | |
|---|---|
position |
int:
where search is to start from. |
| Returns | |
|---|---|
int |
The character index of the first match preceding
position, or DONE if there are
no matches. |
| Throws | |
|---|---|
IndexOutOfBoundsException |
If position is less than or greater than the text range for searching |
See also:
int previous ()
Returns the index of the previous point at which the string text
matches the search pattern, starting at the current position.
The iterator is adjusted so that its current index (as returned by
getIndex()) is the match position if one was found.
If a match is not found, DONE will be returned and
the iterator will be adjusted to the index DONE.
| Returns | |
|---|---|
int |
The index of the previous match before the current position,
or DONE if there are no more matches. |
See also:
void reset ()
Resets the iteration. Search will begin at the start of the text string if a forward iteration is initiated before a backwards iteration. Otherwise if a backwards iteration is initiated before a forwards iteration, the search will begin at the end of the text string.
void setBreakIterator (BreakIterator breakiter)
Set the BreakIterator that will be used to restrict the points at which matches are detected.
| Parameters | |
|---|---|
breakiter |
BreakIterator:
A BreakIterator that will be used to restrict the
points at which matches are detected. If a match is
found, but the match's start or end index is not a
boundary as determined by the BreakIterator,
the match will be rejected and another will be searched
for. If this parameter is null, no break
detection is attempted. |
See also:
void setElementComparisonType (SearchIterator.ElementComparisonType type)
Sets the collation element comparison type.
The default comparison type is STANDARD_ELEMENT_COMPARISON.
| Parameters | |
|---|---|
type |
SearchIterator.ElementComparisonType
|
void setIndex (int position)
Sets the position in the target text at which the next search will start. This method clears any previous match.
| Parameters | |
|---|---|
position |
int:
position from which to start the next search |
| Throws | |
|---|---|
IndexOutOfBoundsException |
thrown if argument position is out of the target text range. |
See also:
void setOverlapping (boolean allowOverlap)
Determines whether overlapping matches are returned. See the class documentation for more information about overlapping matches.
The default setting of this property is false
| Parameters | |
|---|---|
allowOverlap |
boolean:
flag indicator if overlapping matches are allowed |
See also:
void setTarget (CharacterIterator text)
Set the target text to be searched. Text iteration will then begin at the start of the text string. This method is useful if you want to reuse an iterator to search within a different body of text.
| Parameters | |
|---|---|
text |
CharacterIterator:
new text iterator to look for match, |
| Throws | |
|---|---|
IllegalArgumentException |
thrown when text is null or has 0 length |
See also:
int handleNext (int start)
Abstract method which subclasses override to provide the mechanism for finding the next match in the target text. This allows different subclasses to provide different search algorithms.
If a match is found, the implementation should return the index at
which the match starts and should call
setMatchLength(int) with the number of characters
in the target text that make up the match. If no match is found, the
method should return DONE.
| Parameters | |
|---|---|
start |
int:
The index in the target text at which the search
should start. |
| Returns | |
|---|---|
int |
index at which the match starts, else if match is not found
DONE is returned |
See also:
int handlePrevious (int startAt)
Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text. This allows different subclasses to provide different search algorithms.
If a match is found, the implementation should return the index at
which the match starts and should call
setMatchLength(int) with the number of characters
in the target text that make up the match. If no match is found, the
method should return DONE.
| Parameters | |
|---|---|
startAt |
int:
The index in the target text at which the search
should start. |
| Returns | |
|---|---|
int |
index at which the match starts, else if match is not found
DONE is returned |
See also:
void setMatchLength (int length)
Sets the length of the most recent match in the target text. Subclasses' handleNext() and handlePrevious() methods should call this after they find a match in the target text.
| Parameters | |
|---|---|
length |
int:
new length to set |
See also: