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45 * This interface defines a protocol for bidirectional iteration over text.
46 * The iterator iterates over a bounded sequence of characters. Characters
47 * are indexed with values beginning with the value returned by getBeginIndex() and
48 * continuing through the value returned by getEndIndex()-1.
50 * Iterators maintain a current character index, whose valid range is from
51 * getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow
52 * handling of zero-length text ranges and for historical reasons.
53 * The current index can be retrieved by calling getIndex() and set directly
54 * by calling setIndex(), first(), and last().
56 * The methods previous() and next() are used for iteration. They return DONE if
57 * they would move outside the range from getBeginIndex() to getEndIndex() -1,
58 * signaling that the iterator has reached the end of the sequence. DONE is
59 * also returned by other methods to indicate that the current index is
64 * Traverse the text from start to finish
66 * public void traverseForward(CharacterIterator iter) {
67 * for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
73 * Traverse the text backwards, from end to start
75 * public void traverseBackward(CharacterIterator iter) {
76 * for(char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {
82 * Traverse both forward and backward from a given position in the text.
83 * Calls to notBoundary() in this example represents some
84 * additional stopping criteria.
86 * public void traverseOut(CharacterIterator iter, int pos) {
87 * for (char c = iter.setIndex(pos);
88 * c != CharacterIterator.DONE && notBoundary(c);
91 * int end = iter.getIndex();
92 * for (char c = iter.setIndex(pos);
93 * c != CharacterIterator.DONE && notBoundary(c);
94 * c = iter.previous()) {
96 * int start = iter.getIndex();
97 * processSection(start, end);
101 * @see StringCharacterIterator
102 * @see AttributedCharacterIterator
105 public interface CharacterIterator extends Cloneable
109 * Constant that is returned when the iterator has reached either the end
110 * or the beginning of the text. The value is '\\uFFFF', the "not a
111 * character" value which should not occur in any valid Unicode string.
113 public static final char DONE = '\uFFFF';
116 * Sets the position to getBeginIndex() and returns the character at that
118 * @return the first character in the text, or DONE if the text is empty
119 * @see #getBeginIndex()
124 * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
125 * and returns the character at that position.
126 * @return the last character in the text, or DONE if the text is empty
127 * @see #getEndIndex()
132 * Gets the character at the current position (as returned by getIndex()).
133 * @return the character at the current position or DONE if the current
134 * position is off the end of the text.
137 public char current();
140 * Increments the iterator's index by one and returns the character
141 * at the new index. If the resulting index is greater or equal
142 * to getEndIndex(), the current index is reset to getEndIndex() and
143 * a value of DONE is returned.
144 * @return the character at the new position or DONE if the new
145 * position is off the end of the text range.
150 * Decrements the iterator's index by one and returns the character
151 * at the new index. If the current index is getBeginIndex(), the index
152 * remains at getBeginIndex() and a value of DONE is returned.
153 * @return the character at the new position or DONE if the current
154 * position is equal to getBeginIndex().
156 public char previous();
159 * Sets the position to the specified position in the text and returns that
161 * @param position the position within the text. Valid values range from
162 * getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
163 * if an invalid value is supplied.
164 * @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
166 public char setIndex(int position);
169 * Returns the start index of the text.
170 * @return the index at which the text begins.
172 public int getBeginIndex();
175 * Returns the end index of the text. This index is the index of the first
176 * character following the end of the text.
177 * @return the index after the last character in the text
179 public int getEndIndex();
182 * Returns the current index.
183 * @return the current index.
185 public int getIndex();
188 * Create a copy of this iterator
189 * @return A copy of this
191 public Object clone();