SearchIterator (ICU4J 76)

java.lang.Object
- com.ibm.icu.text.SearchIterator

Direct Known Subclasses:

StringSearch
```
public abstract class SearchIterator
extends Object
```
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());
 }
 
```
Author:

Laura Werner, synwee

See Also:

BreakIterator, RuleBasedCollator

Status:
Stable ICU 2.0.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class SearchIterator.ElementComparisonType
Option to control how collation elements are compared.

Nested Classes
Modifier and Type	Class and Description
`static class`	`SearchIterator.ElementComparisonType` Option to control how collation elements are compared.

Field Summary

Fields
Modifier and Type	Field and Description
`protected BreakIterator`	`breakIterator` The BreakIterator to define the boundaries of a logical match.
`static 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.
`protected int`	`matchLength` Length of the most current match in target text.
`protected CharacterIterator`	`targetText` Target text for searching.

Constructor Summary

Constructors
Modifier Constructor and Description

protected SearchIterator(CharacterIterator target, BreakIterator breaker)
Protected constructor for use by subclasses.

Constructors
Modifier	Constructor and Description
`protected`	`SearchIterator(CharacterIterator target, BreakIterator breaker)` Protected constructor for use by subclasses.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`int`	`first()` Returns the first index at which the string text matches the search pattern.
`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.
`String`	`getMatchedText()` Returns the text that was matched by the most recent call to `first()`, `next()`, `previous()`, or `last()`.
`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.
`CharacterIterator`	`getTarget()` Return the string text to be searched.
`protected abstract int`	`handleNext(int start)` Abstract method which subclasses override to provide the mechanism for finding the next match in the target text.
`protected abstract int`	`handlePrevious(int startAt)` Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text.
`boolean`	`isOverlapping()` Return true if the overlapping property has been set.
`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.
`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.
`protected void`	`setMatchLength(int length)` Sets the length of the most recent match in the target text.
`protected void`	`setMatchNotFound()` Deprecated. This API is ICU internal only.
`void`	`setOverlapping(boolean allowOverlap)` Determines whether overlapping matches are returned.
`void`	`setTarget(CharacterIterator text)` Set the target text to be searched.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - breakIterator
```
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
    
    Status:
    Stable ICU 2.0.
  - targetText
```
protected CharacterIterator targetText
```
    Target text for searching.
    
    See Also:
    
    setTarget(CharacterIterator), getTarget()
    
    Status:
    Stable ICU 2.0.
  - matchLength
```
protected int matchLength
```
    Length of the most current match in target text. Value 0 is the default value.
    
    See Also:
    
    setMatchLength(int), getMatchLength()
    
    Status:
    Stable ICU 2.0.
  - DONE
```
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 Field Values
    
    Status:
    Stable ICU 2.0.
- Constructor Detail
  - SearchIterator
```
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 - The target text to be searched.
    
    breaker - 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
    
    Status:
    Stable ICU 2.0.
- Method Detail
  - setIndex
```
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 - position from which to start the next search
    
    Throws:
    
    IndexOutOfBoundsException - thrown if argument position is out of the target text range.
    
    See Also:
    
    getIndex()
    
    Status:
    Stable ICU 2.8.
  - setOverlapping
```
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 - flag indicator if overlapping matches are allowed
    
    See Also:
    
    isOverlapping()
    
    Status:
    Stable ICU 2.8.
  - setBreakIterator
```
public void setBreakIterator(BreakIterator breakiter)
```
    Set the BreakIterator that will be used to restrict the points at which matches are detected.
    
    Parameters:
    
    breakiter - 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
    
    Status:
    Stable ICU 2.0.
  - setTarget
```
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 - new text iterator to look for match,
    
    Throws:
    
    IllegalArgumentException - thrown when text is null or has 0 length
    
    See Also:
    
    getTarget()
    
    Status:
    Stable ICU 2.4.
  - getMatchStart
```
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:
    
    index of a substring within the text string that is being searched.
    
    See Also:
    
    first(), next(), previous(), last()
    
    Status:
    Stable ICU 2.0.
  - getIndex
```
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:
    
    current index in the text being searched.
    
    Status:
    Stable ICU 2.8.
  - getMatchLength
```
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:
    
    The length of the match in the target text, or 0 if there is no match currently.
    
    See Also:
    
    first(), next(), previous(), last()
    
    Status:
    Stable ICU 2.0.
  - getBreakIterator
```
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(com.ibm.icu.text.BreakIterator). If the BreakIterator has not been set, null will be returned. See setBreakIterator(com.ibm.icu.text.BreakIterator) for more information.
    
    Returns:
    
    the BreakIterator set to restrict logic matches
    
    See Also:
    
    setBreakIterator(com.ibm.icu.text.BreakIterator), BreakIterator
    
    Status:
    Stable ICU 2.0.
  - getTarget
```
public CharacterIterator getTarget()
```
    Return the string text to be searched.
    
    Returns:
    
    text string to be searched.
    
    Status:
    Stable ICU 2.0.
  - getMatchedText
```
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:
    
    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()
    
    Status:
    Stable ICU 2.0.
  - next
```
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:
    
    The index of the next match after the current position, or DONE if there are no more matches.
    
    See Also:
    
    getIndex()
    
    Status:
    Stable ICU 2.0.
  - previous
```
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:
    
    The index of the previous match before the current position, or DONE if there are no more matches.
    
    See Also:
    
    getIndex()
    
    Status:
    Stable ICU 2.0.
  - isOverlapping
```
public boolean isOverlapping()
```
    Return true if the overlapping property has been set. See setOverlapping(boolean) for more information.
    
    Returns:
    
    true if the overlapping property has been set, false otherwise
    
    See Also:
    
    setOverlapping(boolean)
    
    Status:
    Stable ICU 2.8.
  - reset
```
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.
    
    Status:
    Stable ICU 2.0.
  - first
```
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:
    
    The character index of the first match, or DONE if there are no matches.
    
    See Also:
    
    getIndex()
    
    Status:
    Stable ICU 2.0.
  - following
```
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 - where search if to start from.
    
    Returns:
    
    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()
    
    Status:
    Stable ICU 2.0.
  - last
```
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:
    
    The index of the first match, or DONE if there are no matches.
    
    See Also:
    
    getIndex()
    
    Status:
    Stable ICU 2.0.
  - preceding
```
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 - where search is to start from.
    
    Returns:
    
    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()
    
    Status:
    Stable ICU 2.0.
  - setMatchLength
```
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 - new length to set
    
    See Also:
    
    handleNext(int), handlePrevious(int)
    
    Status:
    Stable ICU 2.0.
  - handleNext
```
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 - The index in the target text at which the search should start.
    
    Returns:
    
    index at which the match starts, else if match is not found DONE is returned
    
    See Also:
    
    setMatchLength(int)
    
    Status:
    Stable ICU 2.0.
  - handlePrevious
```
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 - The index in the target text at which the search should start.
    
    Returns:
    
    index at which the match starts, else if match is not found DONE is returned
    
    See Also:
    
    setMatchLength(int)
    
    Status:
    Stable ICU 2.0.
  - setMatchNotFound
```
@Deprecated
protected void setMatchNotFound()
```
    Deprecated. This API is ICU internal only.
    
    Status:
    Internal. This API is ICU internal only.
  - setElementComparisonType
```
public void setElementComparisonType(SearchIterator.ElementComparisonType type)
```
    Sets the collation element comparison type.
    The default comparison type is SearchIterator.ElementComparisonType.STANDARD_ELEMENT_COMPARISON.
    
    See Also:
    
    SearchIterator.ElementComparisonType, getElementComparisonType()
    
    Status:
    Stable ICU 53.
  - getElementComparisonType
```
public SearchIterator.ElementComparisonType getElementComparisonType()
```
    Returns the collation element comparison type.
    
    See Also:
    
    SearchIterator.ElementComparisonType, setElementComparisonType(ElementComparisonType)
    
    Status:
    Stable ICU 53.

Class SearchIterator

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

breakIterator

targetText

matchLength

DONE

Constructor Detail

SearchIterator

Method Detail

setIndex

setOverlapping

setBreakIterator

setTarget

getMatchStart

getIndex

getMatchLength

getBreakIterator

getTarget

getMatchedText

next

previous

isOverlapping

reset

first

following

last

preceding

setMatchLength

handleNext

handlePrevious

setMatchNotFound

setElementComparisonType

getElementComparisonType