Package java.text

Class CollationElementIterator

  • public final class CollationElementIterator
extends Object
    Created by a RuleBasedCollator to iterate through a string. The result of each iteration is a 32-bit collation element that defines the ordering priority of the next character or sequence of characters in the source string.

    For illustration, consider the following in Spanish:

    "ca": the first collation element is collation_element('c') and second collation element is collation_element('a').

    Since "ch" in Spanish sorts as one entity, the example below returns one collation element for the two characters 'c' and 'h':

    "cha": the first collation element is collation_element('ch') and the second one is collation_element('a').

    In German, since the character '\u0086' is a composed character of 'a' and 'e', the iterator returns two collation elements for the single character '\u0086':

    "\u0086b": the first collation element is collation_element('a'), the second one is collation_element('e'), and the third collation element is collation_element('b').

    Note that calls to next and previous can not be mixed. To change iteration direction, reset, setOffset or setText must be called to reset the iterator. If a change of direction is done without one of these calls, the result is undefined.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int NULLORDER
      This constant is returned by the iterator in the methods next() and previous() when the end or the beginning of the source string has been reached, and there are no more valid collation elements to return.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int getMaxExpansion​(int order)
      Returns the maximum length of any expansion sequence that ends with the specified collation element.
      int getOffset()
      Returns the character offset in the source string corresponding to the next collation element.
      int next()
      Returns the next collation element in the source string or NULLORDER if the end of the iteration has been reached.
      int previous()
      Returns the previous collation element in the source string or NULLORDER if the start of the iteration has been reached.
      static int primaryOrder​(int order)
      Returns the primary order of the specified collation element, i.e. the first 16 bits.
      void reset()
      Repositions the cursor to point at the first element of the current string.
      static short secondaryOrder​(int order)
      Returns the secondary order of the specified collation element, i.e. the 16th to 23th bits, inclusive.
      void setOffset​(int newOffset)
      Points the iterator at the collation element associated with the character in the source string which is found at the supplied offset.
      void setText​(String source)
      Sets a new source string for iteration, and resets the offset to the beginning of the text.
      void setText​(CharacterIterator source)
      Sets a new source string iterator for iteration, and resets the offset to the beginning of the text.
      static short tertiaryOrder​(int order)
      Returns the tertiary order of the specified collation element, i.e. the last 8 bits.

    • Field Detail

      • NULLORDER

        public static final int NULLORDER
        This constant is returned by the iterator in the methods next() and previous() when the end or the beginning of the source string has been reached, and there are no more valid collation elements to return.
        See Also:
        Constant Field Values

    • Method Detail

      • getMaxExpansion

        public int getMaxExpansion​(int order)
        Returns the maximum length of any expansion sequence that ends with the specified collation element. Returns 1 if there is no expansion with this collation element as the last element.
        Parameters:
        order - a collation element that has been previously obtained from a call to either the next() or previous() method.

      • getOffset

        public int getOffset()
        Returns the character offset in the source string corresponding to the next collation element. This value could be any of:
        • The index of the first character in the source string that matches the value of the next collation element. This means that if setOffset(offset) sets the index in the middle of a contraction, getOffset() returns the index of the first character in the contraction, which may not be equal to the original offset that was set. Hence calling getOffset() immediately after setOffset(offset) does not guarantee that the original offset set will be returned.
        • If normalization is on, the index of the immediate subsequent character, or composite character with the first character, having a combining class of 0.
        • The length of the source string, if iteration has reached the end.

      • next

        public int next()
        Returns the next collation element in the source string or NULLORDER if the end of the iteration has been reached.

      • previous

        public int previous()
        Returns the previous collation element in the source string or NULLORDER if the start of the iteration has been reached.

      • primaryOrder

        public static final int primaryOrder​(int order)
        Returns the primary order of the specified collation element, i.e. the first 16 bits. This value is unsigned.
        Parameters:
        order - the element of the collation.

      • reset

        public void reset()
        Repositions the cursor to point at the first element of the current string. The next call to next() or previous() will return the first and last collation element in the string, respectively.

        If the RuleBasedCollator used by this iterator has had its attributes changed, calling reset() reinitializes the iterator to use the new attributes.

      • secondaryOrder

        public static final short secondaryOrder​(int order)
        Returns the secondary order of the specified collation element, i.e. the 16th to 23th bits, inclusive. This value is unsigned.
        Parameters:
        order - the element of the collator.

      • setOffset

        public void setOffset​(int newOffset)
        Points the iterator at the collation element associated with the character in the source string which is found at the supplied offset. After this call completes, an invocation of the next() method will return this collation element.

        If newOffset corresponds to a character which is part of a sequence that maps to a single collation element then the iterator is adjusted to the start of that sequence. As a result of this, any subsequent call made to getOffset() may not return the same value set by this method.

        If the decomposition mode is on, and offset is in the middle of a decomposable range of source text, the iterator may not return a correct result for the next forwards or backwards iteration. The user must ensure that the offset is not in the middle of a decomposable range.

        Parameters:
        newOffset - the character offset into the original source string to set. Note that this is not an offset into the corresponding sequence of collation elements.

      • setText

        public void setText​(CharacterIterator source)
        Sets a new source string iterator for iteration, and resets the offset to the beginning of the text.
        Parameters:
        source - the new source string iterator for iteration.

      • setText

        public void setText​(String source)
        Sets a new source string for iteration, and resets the offset to the beginning of the text.
        Parameters:
        source - the new source string for iteration.

      • tertiaryOrder

        public static final short tertiaryOrder​(int order)
        Returns the tertiary order of the specified collation element, i.e. the last 8 bits. This value is unsigned.
        Parameters:
        order - the element of the collation.