Java tutorial
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See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved * * The original version of this source code and documentation * is copyrighted and owned by Taligent, Inc., a wholly-owned * subsidiary of IBM. These materials are provided under terms * of a License Agreement between Taligent and Sun. This technology * is protected by multiple US and International patents. * * This notice and attribution to Taligent may not be removed. * Taligent is a registered trademark of Taligent, Inc. * */ package java.text; /** * This interface defines a protocol for bidirectional iteration over text. * The iterator iterates over a bounded sequence of characters. Characters * are indexed with values beginning with the value returned by getBeginIndex() and * continuing through the value returned by getEndIndex()-1. * <p> * Iterators maintain a current character index, whose valid range is from * getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow * handling of zero-length text ranges and for historical reasons. * The current index can be retrieved by calling getIndex() and set directly * by calling setIndex(), first(), and last(). * <p> * The methods previous() and next() are used for iteration. They return DONE if * they would move outside the range from getBeginIndex() to getEndIndex() -1, * signaling that the iterator has reached the end of the sequence. DONE is * also returned by other methods to indicate that the current index is * outside this range. * * <P>Examples:<P> * * Traverse the text from start to finish * <pre>{@code * public void traverseForward(CharacterIterator iter) { * for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) { * processChar(c); * } * } * }</pre> * * Traverse the text backwards, from end to start * <pre>{@code * public void traverseBackward(CharacterIterator iter) { * for(char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) { * processChar(c); * } * } * }</pre> * * Traverse both forward and backward from a given position in the text. * Calls to notBoundary() in this example represents some * additional stopping criteria. * <pre>{@code * public void traverseOut(CharacterIterator iter, int pos) { * for (char c = iter.setIndex(pos); * c != CharacterIterator.DONE && notBoundary(c); * c = iter.next()) { * } * int end = iter.getIndex(); * for (char c = iter.setIndex(pos); * c != CharacterIterator.DONE && notBoundary(c); * c = iter.previous()) { * } * int start = iter.getIndex(); * processSection(start, end); * } * }</pre> * * @since 1.1 * @see StringCharacterIterator * @see AttributedCharacterIterator */ public interface CharacterIterator extends Cloneable { /** * Constant that is returned when the iterator has reached either the end * or the beginning of the text. The value is '\\uFFFF', the "not a * character" value which should not occur in any valid Unicode string. */ public static final char DONE = '\uFFFF'; /** * Sets the position to getBeginIndex() and returns the character at that * position. * @return the first character in the text, or DONE if the text is empty * @see #getBeginIndex() */ public char first(); /** * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty) * and returns the character at that position. * @return the last character in the text, or DONE if the text is empty * @see #getEndIndex() */ public char last(); /** * Gets the character at the current position (as returned by getIndex()). * @return the character at the current position or DONE if the current * position is off the end of the text. * @see #getIndex() */ public char current(); /** * Increments the iterator's index by one and returns the character * at the new index. If the resulting index is greater or equal * to getEndIndex(), the current index is reset to getEndIndex() and * a value of DONE is returned. * @return the character at the new position or DONE if the new * position is off the end of the text range. */ public char next(); /** * Decrements the iterator's index by one and returns the character * at the new index. If the current index is getBeginIndex(), the index * remains at getBeginIndex() and a value of DONE is returned. * @return the character at the new position or DONE if the current * position is equal to getBeginIndex(). */ public char previous(); /** * Sets the position to the specified position in the text and returns that * character. * @param position the position within the text. Valid values range from * getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown * if an invalid value is supplied. * @return the character at the specified position or DONE if the specified position is equal to getEndIndex() */ public char setIndex(int position); /** * Returns the start index of the text. * @return the index at which the text begins. */ public int getBeginIndex(); /** * Returns the end index of the text. This index is the index of the first * character following the end of the text. * @return the index after the last character in the text */ public int getEndIndex(); /** * Returns the current index. * @return the current index. */ public int getIndex(); /** * Create a copy of this iterator * @return A copy of this */ public Object clone(); }