Class UCharacterIterator

java.lang.Object
com.ibm.icu.text.UCharacterIterator
All Implemented Interfaces:
UForwardCharacterIterator, Cloneable

public abstract class UCharacterIterator extends Object implements Cloneable, UForwardCharacterIterator
Abstract class that defines an API for iteration on text objects.This is an interface for forward and backward iteration and random access into a text object. Forward iteration is done with post-increment and backward iteration is done with pre-decrement semantics, while the java.text.CharacterIterator interface methods provided forward iteration with "pre-increment" and backward iteration with pre-decrement semantics. This API is more efficient for forward iteration over code points. The other major difference is that this API can do both code unit and code point iteration, java.text.CharacterIterator can only iterate over code units and is limited to BMP (0 - 0xFFFF)
Author:
Ram
  • Field Summary

    Fields inherited from interface com.ibm.icu.text.UForwardCharacterIterator

    DONE
  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    Protected default constructor for the subclasses
  • Method Summary

    Modifier and Type
    Method
    Description
    Creates a copy of this iterator, independent from other iterators.
    abstract int
    Returns the code unit at the current index.
    int
    Returns the codepoint at the current index.
    Returns a java.text.CharacterIterator object for the underlying text of this iterator.
    abstract int
    Gets the current index in text.
    static final UCharacterIterator
    getInstance(char[] source)
    Returns a UCharacterIterator object given a source character array.
    static final UCharacterIterator
    getInstance(char[] source, int start, int limit)
    Returns a UCharacterIterator object given a source character array.
    static final UCharacterIterator
    Returns a UCharacterIterator object given a Replaceable object.
    static final UCharacterIterator
    Returns a UCharacterIterator object given a source string.
    static final UCharacterIterator
    Returns a UCharacterIterator object given a source StringBuffer.
    static final UCharacterIterator
    Returns a UCharacterIterator object given a CharacterIterator.
    abstract int
    Returns the length of the text
    Convenience method for returning the underlying text storage as as string
    final int
    getText(char[] fillIn)
    Convenience override for getText(char[], int) that provides an offset of 0.
    abstract int
    getText(char[] fillIn, int offset)
    Fills the buffer with the underlying text storage of the iterator If the buffer capacity is not enough a exception is thrown.
    int
    moveCodePointIndex(int delta)
    Moves the current position by the number of code points specified, either forward or backward depending on the sign of delta (positive or negative respectively).
    int
    moveIndex(int delta)
    Moves the current position by the number of code units specified, either forward or backward depending on the sign of delta (positive or negative respectively).
    abstract int
    Returns the UTF16 code unit at index, and increments to the next code unit (post-increment semantics).
    int
    Returns the code point at index, and increments to the next code point (post-increment semantics).
    abstract int
    Decrement to the position of the previous code unit in the text, and return it (pre-decrement semantics).
    int
    Retreat to the start of the previous code point in the text, and return it (pre-decrement semantics).
    abstract void
    setIndex(int index)
    Sets the index to the specified index in the text.
    void
    Sets the current index to the limit.
    void
    Sets the current index to the start.

    Methods inherited from class java.lang.Object

    equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • UCharacterIterator

      protected UCharacterIterator()
      Protected default constructor for the subclasses
  • Method Details

    • getInstance

      public static final UCharacterIterator getInstance(Replaceable source)
      Returns a UCharacterIterator object given a Replaceable object.
      Parameters:
      source - a valid source as a Replaceable object
      Returns:
      UCharacterIterator object
      Throws:
      IllegalArgumentException - if the argument is null
    • getInstance

      public static final UCharacterIterator getInstance(String source)
      Returns a UCharacterIterator object given a source string.
      Parameters:
      source - a string
      Returns:
      UCharacterIterator object
      Throws:
      IllegalArgumentException - if the argument is null
    • getInstance

      public static final UCharacterIterator getInstance(char[] source)
      Returns a UCharacterIterator object given a source character array.
      Parameters:
      source - an array of UTF-16 code units
      Returns:
      UCharacterIterator object
      Throws:
      IllegalArgumentException - if the argument is null
    • getInstance

      public static final UCharacterIterator getInstance(char[] source, int start, int limit)
      Returns a UCharacterIterator object given a source character array.
      Parameters:
      source - an array of UTF-16 code units
      Returns:
      UCharacterIterator object
      Throws:
      IllegalArgumentException - if the argument is null
    • getInstance

      public static final UCharacterIterator getInstance(StringBuffer source)
      Returns a UCharacterIterator object given a source StringBuffer.
      Parameters:
      source - an string buffer of UTF-16 code units
      Returns:
      UCharacterIterator object
      Throws:
      IllegalArgumentException - if the argument is null
    • getInstance

      public static final UCharacterIterator getInstance(CharacterIterator source)
      Returns a UCharacterIterator object given a CharacterIterator.
      Parameters:
      source - a valid CharacterIterator object.
      Returns:
      UCharacterIterator object
      Throws:
      IllegalArgumentException - if the argument is null
    • getCharacterIterator

      public CharacterIterator getCharacterIterator()
      Returns a java.text.CharacterIterator object for the underlying text of this iterator. The returned iterator is independent of this iterator.
      Returns:
      java.text.CharacterIterator object
    • current

      public abstract int current()
      Returns the code unit at the current index. If index is out of range, returns DONE. Index is not changed.
      Returns:
      current code unit
    • currentCodePoint

      public int currentCodePoint()
      Returns the codepoint at the current index. If the current index is invalid, DONE is returned. If the current index points to a lead surrogate, and there is a following trail surrogate, then the code point is returned. Otherwise, the code unit at index is returned. Index is not changed.
      Returns:
      current codepoint
    • getLength

      public abstract int getLength()
      Returns the length of the text
      Returns:
      length of the text
    • getIndex

      public abstract int getIndex()
      Gets the current index in text.
      Returns:
      current index in text.
    • next

      public abstract int next()
      Returns the UTF16 code unit at index, and increments to the next code unit (post-increment semantics). If index is out of range, DONE is returned, and the iterator is reset to the limit of the text.
      Specified by:
      next in interface UForwardCharacterIterator
      Returns:
      the next UTF16 code unit, or DONE if the index is at the limit of the text.
    • nextCodePoint

      public int nextCodePoint()
      Returns the code point at index, and increments to the next code point (post-increment semantics). If index does not point to a valid surrogate pair, the behavior is the same as next(). Otherwise the iterator is incremented past the surrogate pair, and the code point represented by the pair is returned.
      Specified by:
      nextCodePoint in interface UForwardCharacterIterator
      Returns:
      the next codepoint in text, or DONE if the index is at the limit of the text.
    • previous

      public abstract int previous()
      Decrement to the position of the previous code unit in the text, and return it (pre-decrement semantics). If the resulting index is less than 0, the index is reset to 0 and DONE is returned.
      Returns:
      the previous code unit in the text, or DONE if the new index is before the start of the text.
    • previousCodePoint

      public int previousCodePoint()
      Retreat to the start of the previous code point in the text, and return it (pre-decrement semantics). If the index is not preceded by a valid surrogate pair, the behavior is the same as previous(). Otherwise the iterator is decremented to the start of the surrogate pair, and the code point represented by the pair is returned.
      Returns:
      the previous code point in the text, or DONE if the new index is before the start of the text.
    • setIndex

      public abstract void setIndex(int index)
      Sets the index to the specified index in the text.
      Parameters:
      index - the index within the text.
      Throws:
      IndexOutOfBoundsException - is thrown if an invalid index is supplied
    • setToLimit

      public void setToLimit()
      Sets the current index to the limit.
    • setToStart

      public void setToStart()
      Sets the current index to the start.
    • getText

      public abstract int getText(char[] fillIn, int offset)
      Fills the buffer with the underlying text storage of the iterator If the buffer capacity is not enough a exception is thrown. The capacity of the fill in buffer should at least be equal to length of text in the iterator obtained by calling getLength()). Usage:
               UChacterIterator iter = new UCharacterIterator.getInstance(text);
               char[] buf = new char[iter.getLength()];
               iter.getText(buf);
      
               OR
               char[] buf= new char[1];
               int len = 0;
               for(;;){
                   try{
                       len = iter.getText(buf);
                       break;
                   }catch(IndexOutOfBoundsException e){
                       buf = new char[iter.getLength()];
                   }
               }
       
      Parameters:
      fillIn - an array of chars to fill with the underlying UTF-16 code units.
      offset - the position within the array to start putting the data.
      Returns:
      the number of code units added to fillIn, as a convenience
      Throws:
      IndexOutOfBoundsException - exception if there is not enough room after offset in the array, or if offset < 0.
    • getText

      public final int getText(char[] fillIn)
      Convenience override for getText(char[], int) that provides an offset of 0.
      Parameters:
      fillIn - an array of chars to fill with the underlying UTF-16 code units.
      Returns:
      the number of code units added to fillIn, as a convenience
      Throws:
      IndexOutOfBoundsException - exception if there is not enough room in the array.
    • getText

      public String getText()
      Convenience method for returning the underlying text storage as as string
      Returns:
      the underlying text storage in the iterator as a string
    • moveIndex

      public int moveIndex(int delta)
      Moves the current position by the number of code units specified, either forward or backward depending on the sign of delta (positive or negative respectively). If the resulting index would be less than zero, the index is set to zero, and if the resulting index would be greater than limit, the index is set to limit.
      Parameters:
      delta - the number of code units to move the current index.
      Returns:
      the new index.
      Throws:
      IndexOutOfBoundsException - is thrown if an invalid index is supplied
    • moveCodePointIndex

      public int moveCodePointIndex(int delta)
      Moves the current position by the number of code points specified, either forward or backward depending on the sign of delta (positive or negative respectively). If the current index is at a trail surrogate then the first adjustment is by code unit, and the remaining adjustments are by code points. If the resulting index would be less than zero, the index is set to zero, and if the resulting index would be greater than limit, the index is set to limit.
      Parameters:
      delta - the number of code units to move the current index.
      Returns:
      the new index
      Throws:
      IndexOutOfBoundsException - is thrown if an invalid delta is supplied
    • clone

      public Object clone() throws CloneNotSupportedException
      Creates a copy of this iterator, independent from other iterators. If it is not possible to clone the iterator, returns null.
      Overrides:
      clone in class Object
      Returns:
      copy of this iterator
      Throws:
      CloneNotSupportedException