CollationElementIterator class is used as an iterator
* to walk through each character of an international string. Use the iterator
* to return the ordering priority of the positioned character. The ordering
* priority of a character, which we refer to as a key, defines how a character
* is collated in the given collation object.
*
* * For example, consider the following in Spanish: *
*
* "ca" → the first key is key('c') and second key is key('a').
* "cha" → the first key is key('ch') and second key is key('a').
*
*
* And in German,
*
*
* "\u00e4b" → the first key is key('a'), the second key is key('e'), and
* the third key is key('b').
*
*
* The key of a character is an integer composed of primary order(short),
* secondary order(byte), and tertiary order(byte). Java strictly defines
* the size and signedness of its primitive data types. Therefore, the static
* functions primaryOrder, secondaryOrder, and
* tertiaryOrder return int, short,
* and short respectively to ensure the correctness of the key
* value.
*
* * Example of the iterator usage, *
*
*
* String testString = "This is a test";
* Collator col = Collator.getInstance();
* if (col instanceof RuleBasedCollator) {
* RuleBasedCollator ruleBasedCollator = (RuleBasedCollator)col;
* CollationElementIterator collationElementIterator = ruleBasedCollator.getCollationElementIterator(testString);
* int primaryOrder = CollationElementIterator.primaryOrder(collationElementIterator.next());
* :
* }
*
*
*
*
* CollationElementIterator.next returns the collation order
* of the next character. A collation order consists of primary order,
* secondary order and tertiary order. The data type of the collation
* order is int. The first 16 bits of a collation order
* is its primary order; the next 8 bits is the secondary order and the
* last 8 bits is the tertiary order.
*
*
Note: CollationElementIterator is a part of
* RuleBasedCollator implementation. It is only usable
* with RuleBasedCollator instances.
*
* @see Collator
* @see RuleBasedCollator
* @author Helena Shih, Laura Werner, Richard Gillam
*/
public final class CollationElementIterator
{
/**
* Null order which indicates the end of string is reached by the
* cursor.
*/
public final static int NULLORDER = android.icu.text.CollationElementIterator.NULLORDER;
private android.icu.text.CollationElementIterator icuIterator;
CollationElementIterator(android.icu.text.CollationElementIterator iterator) {
icuIterator = iterator;
}
/**
* Resets the cursor to the beginning of the string. The next call
* to next() will return the first collation element in the string.
*/
public void reset()
{
icuIterator.reset();
}
/**
* Get the next collation element in the string.
This iterator iterates * over a sequence of collation elements that were built from the string. * Because there isn't necessarily a one-to-one mapping from characters to * collation elements, this doesn't mean the same thing as "return the * collation element [or ordering priority] of the next character in the * string".
*This function returns the collation element that the iterator is currently * pointing to and then updates the internal pointer to point to the next element. * previous() updates the pointer first and then returns the element. This * means that when you change direction while iterating (i.e., call next() and * then call previous(), or call previous() and then call next()), you'll get * back the same element twice.
* * @return the next collation element */ public int next() { return icuIterator.next(); } /** * Get the previous collation element in the string.This iterator iterates * over a sequence of collation elements that were built from the string. * Because there isn't necessarily a one-to-one mapping from characters to * collation elements, this doesn't mean the same thing as "return the * collation element [or ordering priority] of the previous character in the * string".
*This function updates the iterator's internal pointer to point to the * collation element preceding the one it's currently pointing to and then * returns that element, while next() returns the current element and then * updates the pointer. This means that when you change direction while * iterating (i.e., call next() and then call previous(), or call previous() * and then call next()), you'll get back the same element twice.
* * @return the previous collation element * @since 1.2 */ public int previous() { return icuIterator.previous(); } /** * Return the primary component of a collation element. * @param order the collation element * @return the element's primary component */ public final static int primaryOrder(int order) { return android.icu.text.CollationElementIterator.primaryOrder(order); } /** * Return the secondary component of a collation element. * @param order the collation element * @return the element's secondary component */ public final static short secondaryOrder(int order) { return (short) android.icu.text.CollationElementIterator.secondaryOrder(order); } /** * Return the tertiary component of a collation element. * @param order the collation element * @return the element's tertiary component */ public final static short tertiaryOrder(int order) { return (short) android.icu.text.CollationElementIterator.tertiaryOrder(order); } /** * Sets the iterator to point to the collation element corresponding to * the specified character (the parameter is a CHARACTER offset in the * original string, not an offset into its corresponding sequence of * collation elements). The value returned by the next call to next() * will be the collation element corresponding to the specified position * in the text. If that position is in the middle of a contracting * character sequence, the result of the next call to next() is the * collation element for that sequence. This means that getOffset() * is not guaranteed to return the same value as was passed to a preceding * call to setOffset(). * * @param newOffset The new character offset into the original text. * @since 1.2 */ @SuppressWarnings("deprecation") // getBeginIndex, getEndIndex and setIndex are deprecated public void setOffset(int newOffset) { icuIterator.setOffset(newOffset); } /** * Returns the character offset in the original text corresponding to the next * collation element. (That is, getOffset() returns the position in the text * corresponding to the collation element that will be returned by the next * call to next().) This value will always be the index of the FIRST character * corresponding to the collation element (a contracting character sequence is * when two or more characters all correspond to the same collation element). * This means if you do setOffset(x) followed immediately by getOffset(), getOffset() * won't necessarily return x. * * @return The character offset in the original text corresponding to the collation * element that will be returned by the next call to next(). * @since 1.2 */ public int getOffset() { return icuIterator.getOffset(); } /** * Return the maximum length of any expansion sequences that end * with the specified comparison order. * @param order a collation order returned by previous or next. * @return the maximum length of any expansion sequences ending * with the specified order. * @since 1.2 */ public int getMaxExpansion(int order) { return icuIterator.getMaxExpansion(order); } /** * Set a new string over which to iterate. * * @param source the new source text * @since 1.2 */ public void setText(String source) { icuIterator.setText(source); } /** * Set a new string over which to iterate. * * @param source the new source text. * @since 1.2 */ public void setText(CharacterIterator source) { icuIterator.setText(source); } }