Added in API level 24

Summary: Constants | Fields | Protected Ctors | Methods | Protected Methods | Inherited Methods

SearchIterator

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Kotlin |Java

public abstract class SearchIterator
extends Object

java.lang.Object
↳	android.icu.text.SearchIterator

Known direct subclasses StringSearch StringSearch StringSearch is a SearchIterator that provides language-sensitive text searching based on the comparison rules defined in a RuleBasedCollator object.

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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.

 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:

• BreakIterator
• RuleBasedCollator

Summary

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 first(), next(), previous(), or last().
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 getIndex()) is the match position if one was found.
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 Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Constants

DONE

Added in API level 24

public static final 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:

• previous()
• next()

Constant Value: -1 (0xffffffff)

Fields

breakIterator

Added in API level 24

protected BreakIterator breakIterator

The BreakIterator to define the boundaries of a logical match. This value can be a null. See class documentation for more information.

See also:

• setBreakIterator(BreakIterator)
• getBreakIterator()
• BreakIterator

matchLength

Added in API level 24

protected int matchLength

Length of the most current match in target text. Value 0 is the default value.

See also:

• setMatchLength(int)
• getMatchLength()

targetText

Added in API level 24

protected CharacterIterator targetText

Target text for searching.

See also:

• setTarget(CharacterIterator)
• getTarget()

Protected constructors

SearchIterator

Added in API level 24

protected 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:

• BreakIterator

Public methods

first

Added in API level 24

public final 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:

• getIndex()

following

Added in API level 24

public final 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:

• getIndex()

getBreakIterator

Added in API level 24

public 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

See also:

• setBreakIterator(BreakIterator)
• BreakIterator

getElementComparisonType

Added in API level 24

public SearchIterator.ElementComparisonType getElementComparisonType ()

Returns the collation element comparison type.

Returns
SearchIterator.ElementComparisonType

See also:

• SearchIterator.ElementComparisonType
• setElementComparisonType(ElementComparisonType)

getIndex

Added in API level 24

public abstract 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.

getMatchLength

Added in API level 24

public 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:

• first()
• next()
• previous()
• last()

getMatchStart

Added in API level 24

public 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:

• first()
• next()
• previous()
• last()

getMatchedText

Added in API level 24

public 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:

• first()
• next()
• previous()
• last()

getTarget

Added in API level 24

public CharacterIterator getTarget ()

Return the string text to be searched.

Returns
CharacterIterator	text string to be searched.

isOverlapping

Added in API level 24

public 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:

• setOverlapping(boolean)

last

Added in API level 24

public final 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:

• getIndex()

next

Added in API level 24

public 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:

• getIndex()

preceding

Added in API level 24

public final 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:

• getIndex()

previous

Added in API level 24

public 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:

• getIndex()

reset

Added in API level 24

public 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.

setBreakIterator

Added in API level 24

public 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:

• BreakIterator

setElementComparisonType

Added in API level 24

public void setElementComparisonType (SearchIterator.ElementComparisonType type)

Sets the collation element comparison type.

The default comparison type is ElementComparisonType.STANDARD_ELEMENT_COMPARISON.

Parameters
type	SearchIterator.ElementComparisonType

See also:

• SearchIterator.ElementComparisonType
• getElementComparisonType()

setIndex

Added in API level 24

public 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:

• getIndex()

setOverlapping

Added in API level 24

public 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:

• isOverlapping()

setTarget

Added in API level 24

public 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:

• getTarget()

Protected methods

handleNext

Added in API level 24

protected abstract 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:

• setMatchLength(int)

handlePrevious

Added in API level 24

protected abstract 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:

• setMatchLength(int)

setMatchLength

Added in API level 24

protected 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:

• handleNext(int)
• handlePrevious(int)