The FieldPosition.java Java example source code
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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/*
* (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
* (C) Copyright IBM Corp. 1996 - 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;
/**
* <code>FieldPosition is a simple class used by Format
* and its subclasses to identify fields in formatted output. Fields can
* be identified in two ways:
* <ul>
* <li>By an integer constant, whose names typically end with
* <code>_FIELD. The constants are defined in the various
* subclasses of <code>Format.
* <li>By a Format.Field constant, see ERA_FIELD
* and its friends in <code>DateFormat for an example.
* </ul>
* <p>
* <code>FieldPosition keeps track of the position of the
* field within the formatted output with two indices: the index
* of the first character of the field and the index of the last
* character of the field.
*
* <p>
* One version of the <code>format method in the various
* <code>Format classes requires a FieldPosition
* object as an argument. You use this <code>format method
* to perform partial formatting or to get information about the
* formatted output (such as the position of a field).
*
* <p>
* If you are interested in the positions of all attributes in the
* formatted string use the <code>Format method
* <code>formatToCharacterIterator.
*
* @author Mark Davis
* @see java.text.Format
*/
public class FieldPosition {
/**
* Input: Desired field to determine start and end offsets for.
* The meaning depends on the subclass of Format.
*/
int field = 0;
/**
* Output: End offset of field in text.
* If the field does not occur in the text, 0 is returned.
*/
int endIndex = 0;
/**
* Output: Start offset of field in text.
* If the field does not occur in the text, 0 is returned.
*/
int beginIndex = 0;
/**
* Desired field this FieldPosition is for.
*/
private Format.Field attribute;
/**
* Creates a FieldPosition object for the given field. Fields are
* identified by constants, whose names typically end with _FIELD,
* in the various subclasses of Format.
*
* @param field the field identifier
* @see java.text.NumberFormat#INTEGER_FIELD
* @see java.text.NumberFormat#FRACTION_FIELD
* @see java.text.DateFormat#YEAR_FIELD
* @see java.text.DateFormat#MONTH_FIELD
*/
public FieldPosition(int field) {
this.field = field;
}
/**
* Creates a FieldPosition object for the given field constant. Fields are
* identified by constants defined in the various <code>Format
* subclasses. This is equivalent to calling
* <code>new FieldPosition(attribute, -1).
*
* @param attribute Format.Field constant identifying a field
* @since 1.4
*/
public FieldPosition(Format.Field attribute) {
this(attribute, -1);
}
/**
* Creates a <code>FieldPosition object for the given field.
* The field is identified by an attribute constant from one of the
* <code>Field subclasses as well as an integer field ID
* defined by the <code>Format subclasses. Format
* subclasses that are aware of <code>Field should give precedence
* to <code>attribute and ignore fieldID if
* <code>attribute is not null. However, older Format
* subclasses may not be aware of <code>Field and rely on
* <code>fieldID. If the field has no corresponding integer
* constant, <code>fieldID should be -1.
*
* @param attribute Format.Field constant identifying a field
* @param fieldID integer constant identifying a field
* @since 1.4
*/
public FieldPosition(Format.Field attribute, int fieldID) {
this.attribute = attribute;
this.field = fieldID;
}
/**
* Returns the field identifier as an attribute constant
* from one of the <code>Field subclasses. May return null if
* the field is specified only by an integer field ID.
*
* @return Identifier for the field
* @since 1.4
*/
public Format.Field getFieldAttribute() {
return attribute;
}
/**
* Retrieves the field identifier.
*
* @return the field identifier
*/
public int getField() {
return field;
}
/**
* Retrieves the index of the first character in the requested field.
*
* @return the begin index
*/
public int getBeginIndex() {
return beginIndex;
}
/**
* Retrieves the index of the character following the last character in the
* requested field.
*
* @return the end index
*/
public int getEndIndex() {
return endIndex;
}
/**
* Sets the begin index. For use by subclasses of Format.
*
* @param bi the begin index
* @since 1.2
*/
public void setBeginIndex(int bi) {
beginIndex = bi;
}
/**
* Sets the end index. For use by subclasses of Format.
*
* @param ei the end index
* @since 1.2
*/
public void setEndIndex(int ei) {
endIndex = ei;
}
/**
* Returns a <code>Format.FieldDelegate instance that is associated
* with the FieldPosition. When the delegate is notified of the same
* field the FieldPosition is associated with, the begin/end will be
* adjusted.
*/
Format.FieldDelegate getFieldDelegate() {
return new Delegate();
}
/**
* Overrides equals
*/
public boolean equals(Object obj)
{
if (obj == null) return false;
if (!(obj instanceof FieldPosition))
return false;
FieldPosition other = (FieldPosition) obj;
if (attribute == null) {
if (other.attribute != null) {
return false;
}
}
else if (!attribute.equals(other.attribute)) {
return false;
}
return (beginIndex == other.beginIndex
&& endIndex == other.endIndex
&& field == other.field);
}
/**
* Returns a hash code for this FieldPosition.
* @return a hash code value for this object
*/
public int hashCode() {
return (field << 24) | (beginIndex << 16) | endIndex;
}
/**
* Return a string representation of this FieldPosition.
* @return a string representation of this object
*/
public String toString() {
return getClass().getName() +
"[field=" + field + ",attribute=" + attribute +
",beginIndex=" + beginIndex +
",endIndex=" + endIndex + ']';
}
/**
* Return true if the receiver wants a <code>Format.Field value and
* <code>attribute is equal to it.
*/
private boolean matchesField(Format.Field attribute) {
if (this.attribute != null) {
return this.attribute.equals(attribute);
}
return false;
}
/**
* Return true if the receiver wants a <code>Format.Field value and
* <code>attribute is equal to it, or true if the receiver
* represents an inteter constant and <code>field equals it.
*/
private boolean matchesField(Format.Field attribute, int field) {
if (this.attribute != null) {
return this.attribute.equals(attribute);
}
return (field == this.field);
}
/**
* An implementation of FieldDelegate that will adjust the begin/end
* of the FieldPosition if the arguments match the field of
* the FieldPosition.
*/
private class Delegate implements Format.FieldDelegate {
/**
* Indicates whether the field has been encountered before. If this
* is true, and <code>formatted is invoked, the begin/end
* are not updated.
*/
private boolean encounteredField;
public void formatted(Format.Field attr, Object value, int start,
int end, StringBuffer buffer) {
if (!encounteredField && matchesField(attr)) {
setBeginIndex(start);
setEndIndex(end);
encounteredField = (start != end);
}
}
public void formatted(int fieldID, Format.Field attr, Object value,
int start, int end, StringBuffer buffer) {
if (!encounteredField && matchesField(attr, fieldID)) {
setBeginIndex(start);
setEndIndex(end);
encounteredField = (start != end);
}
}
}
}
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