public final class CollationElementIterator extends Object
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,
"äb" → 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.
Collator,
RuleBasedCollator| 限定符和类型 | 字段 | 说明 |
|---|---|---|
static int |
NULLORDER |
Null order which indicates the end of string is reached by the
cursor.
|
| 限定符和类型 | 方法 | 说明 |
|---|---|---|
int |
getMaxExpansion(int order) |
Return the maximum length of any expansion sequences that end
with the specified comparison order.
|
int |
getOffset() |
Returns the character offset in the original text corresponding to the next
collation element.
|
int |
next() |
Get the next collation element in the string.
|
int |
previous() |
Get the previous collation element in the string.
|
static int |
primaryOrder(int order) |
Return the primary component of a collation element.
|
void |
reset() |
Resets the cursor to the beginning of the string.
|
static short |
secondaryOrder(int order) |
Return the secondary component of a collation element.
|
void |
setOffset(int newOffset) |
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).
|
void |
setText(String source) |
Set a new string over which to iterate.
|
void |
setText(CharacterIterator source) |
Set a new string over which to iterate.
|
static short |
tertiaryOrder(int order) |
Return the tertiary component of a collation element.
|
public static final int NULLORDER
public void reset()
public int next()
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.
public int previous()
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.
public static int primaryOrder(int order)
order - the collation elementpublic static short secondaryOrder(int order)
order - the collation elementpublic static short tertiaryOrder(int order)
order - the collation elementpublic void setOffset(int newOffset)
newOffset - The new character offset into the original text.public int getOffset()
public int getMaxExpansion(int order)
order - a collation order returned by previous or next.public void setText(String source)
source - the new source textpublic void setText(CharacterIterator source)
source - the new source text.