java.text.ChoiceFormat Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.text;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;
import libcore.util.EmptyArray;
/**
* Returns a fixed string based on a numeric value. The class can be used in
* conjunction with the {@link MessageFormat} class to handle plurals in
* messages. {@code ChoiceFormat} enables users to attach a format to a range of
* numbers. The choice is specified with an ascending list of doubles, where
* each item specifies a half-open interval up to the next item as in the
* following: X matches j if and only if {@code limit[j] <= X < limit[j+1]}.
*
* If there is no match, then either the first or last index is used. The first
* or last index is used depending on whether the number is too low or too high.
* The length of the format array must be the same as the length of the limits
* array.
*
Examples:
*
*
*
* double[] limits = {1, 2, 3, 4, 5, 6, 7};
* String[] fmts = {"Sun", "Mon", "Tue", "Wed", "Thur", "Fri", "Sat"};
*
* double[] limits2 = {0, 1, ChoiceFormat.nextDouble(1)};
* String[] fmts2 = {"no files", "one file", "many files"};
*
*
*
* ChoiceFormat.nextDouble(double) allows to get the double following the one
* passed to the method. This is used to create half open intervals.
*
* {@code ChoiceFormat} objects also may be converted to and from patterns.
* The conversion can be done programmatically, as in the example above, or
* by using a pattern like the following:
*
*
*
* "1#Sun|2#Mon|3#Tue|4#Wed|5#Thur|6#Fri|7#Sat"
* "0#are no files|1#is one file|1<are many files"
*
*
*
*
* where:
*
* "#" specifies an inclusive limit value;"<" specifies an exclusive limit value.
*/
public class ChoiceFormat extends NumberFormat {
private static final long serialVersionUID = 1795184449645032964L;
private double[] choiceLimits;
private String[] choiceFormats;
/**
* Constructs a new {@code ChoiceFormat} with the specified double values
* and associated strings. When calling
* {@link #format(double, StringBuffer, FieldPosition) format} with a double
* value {@code d}, then the element {@code i} in {@code formats} is
* selected where {@code i} fulfills {@code limits[i] <= d < limits[i+1]}.
*
* The length of the {@code limits} and {@code formats} arrays must be the
* same.
*
* @param limits
* an array of doubles in ascending order. The lowest and highest
* possible values are negative and positive infinity.
* @param formats
* the strings associated with the ranges defined through {@code
* limits}. The lower bound of the associated range is at the
* same index as the string.
*/
public ChoiceFormat(double[] limits, String[] formats) {
setChoices(limits, formats);
}
/**
* Constructs a new {@code ChoiceFormat} with the strings and limits parsed
* from the specified pattern.
*
* @param template
* the pattern of strings and ranges.
* @throws IllegalArgumentException
* if an error occurs while parsing the pattern.
*/
public ChoiceFormat(String template) {
applyPattern(template);
}
/**
* Parses the pattern to determine new strings and ranges for this
* {@code ChoiceFormat}.
*
* @param template
* the pattern of strings and ranges.
* @throws IllegalArgumentException
* if an error occurs while parsing the pattern.
*/
public void applyPattern(String template) {
double[] limits = new double[5];
List formats = new ArrayList();
int length = template.length(), limitCount = 0, index = 0;
StringBuffer buffer = new StringBuffer();
NumberFormat format = NumberFormat.getInstance(Locale.US);
ParsePosition position = new ParsePosition(0);
while (true) {
index = skipWhitespace(template, index);
if (index >= length) {
if (limitCount == limits.length) {
choiceLimits = limits;
} else {
choiceLimits = new double[limitCount];
System.arraycopy(limits, 0, choiceLimits, 0, limitCount);
}
choiceFormats = new String[formats.size()];
for (int i = 0; i < formats.size(); i++) {
choiceFormats[i] = formats.get(i);
}
return;
}
position.setIndex(index);
Number value = format.parse(template, position);
index = skipWhitespace(template, position.getIndex());
if (position.getErrorIndex() != -1 || index >= length) {
// Fix Harmony 540
choiceLimits = EmptyArray.DOUBLE;
choiceFormats = EmptyArray.STRING;
return;
}
char ch = template.charAt(index++);
if (limitCount == limits.length) {
double[] newLimits = new double[limitCount * 2];
System.arraycopy(limits, 0, newLimits, 0, limitCount);
limits = newLimits;
}
double next;
switch (ch) {
case '#':
case '\u2264':
next = value.doubleValue();
break;
case '<':
next = nextDouble(value.doubleValue());
break;
default:
throw new IllegalArgumentException("Bad character '" + ch + "' in template: " + template);
}
if (limitCount > 0 && next <= limits[limitCount - 1]) {
throw new IllegalArgumentException("Bad template: " + template);
}
buffer.setLength(0);
position.setIndex(index);
upTo(template, position, buffer, '|');
index = position.getIndex();
limits[limitCount++] = next;
formats.add(buffer.toString());
}
}
/**
* Returns a new instance of {@code ChoiceFormat} with the same ranges and
* strings as this {@code ChoiceFormat}.
*
* @return a shallow copy of this {@code ChoiceFormat}.
*
* @see java.lang.Cloneable
*/
@Override
public Object clone() {
ChoiceFormat clone = (ChoiceFormat) super.clone();
clone.choiceLimits = choiceLimits.clone();
clone.choiceFormats = choiceFormats.clone();
return clone;
}
/**
* Compares the specified object with this {@code ChoiceFormat}. The object
* must be an instance of {@code ChoiceFormat} and have the same limits and
* formats to be equal to this instance.
*
* @param object
* the object to compare with this instance.
* @return {@code true} if the specified object is equal to this instance;
* {@code false} otherwise.
* @see #hashCode
*/
@Override
public boolean equals(Object object) {
if (this == object) {
return true;
}
if (!(object instanceof ChoiceFormat)) {
return false;
}
ChoiceFormat choice = (ChoiceFormat) object;
return Arrays.equals(choiceLimits, choice.choiceLimits)
&& Arrays.equals(choiceFormats, choice.choiceFormats);
}
/**
* Appends the string associated with the range in which the specified
* double value fits to the specified string buffer.
*
* @param value
* the double to format.
* @param buffer
* the target string buffer to append the formatted value to.
* @param field
* a {@code FieldPosition} which is ignored.
* @return the string buffer.
*/
@Override
public StringBuffer format(double value, StringBuffer buffer,
FieldPosition field) {
for (int i = choiceLimits.length - 1; i >= 0; i--) {
if (choiceLimits[i] <= value) {
return buffer.append(choiceFormats[i]);
}
}
return choiceFormats.length == 0 ? buffer : buffer
.append(choiceFormats[0]);
}
/**
* Appends the string associated with the range in which the specified long
* value fits to the specified string buffer.
*
* @param value
* the long to format.
* @param buffer
* the target string buffer to append the formatted value to.
* @param field
* a {@code FieldPosition} which is ignored.
* @return the string buffer.
*/
@Override
public StringBuffer format(long value, StringBuffer buffer,
FieldPosition field) {
return format((double) value, buffer, field);
}
/**
* Returns the strings associated with the ranges of this {@code
* ChoiceFormat}.
*
* @return an array of format strings.
*/
public Object[] getFormats() {
return choiceFormats;
}
/**
* Returns the limits of this {@code ChoiceFormat}.
*
* @return the array of doubles which make up the limits of this {@code
* ChoiceFormat}.
*/
public double[] getLimits() {
return choiceLimits;
}
/**
* Returns an integer hash code for the receiver. Objects which are equal
* return the same value for this method.
*
* @return the receiver's hash.
*
* @see #equals
*/
@Override
public int hashCode() {
int hashCode = 0;
for (int i = 0; i < choiceLimits.length; i++) {
long v = Double.doubleToLongBits(choiceLimits[i]);
hashCode += (int) (v ^ (v >>> 32)) + choiceFormats[i].hashCode();
}
return hashCode;
}
/**
* Returns the double value which is closest to the specified double but
* larger.
*
* @param value
* a double value.
* @return the next larger double value.
*/
public static final double nextDouble(double value) {
if (value == Double.POSITIVE_INFINITY) {
return value;
}
long bits;
// Handle -0.0
if (value == 0) {
bits = 0;
} else {
bits = Double.doubleToLongBits(value);
}
return Double.longBitsToDouble(value < 0 ? bits - 1 : bits + 1);
}
/**
* Returns the double value which is closest to the specified double but
* either larger or smaller as specified.
*
* @param value
* a double value.
* @param increment
* {@code true} to get the next larger value, {@code false} to
* get the previous smaller value.
* @return the next larger or smaller double value.
*/
public static double nextDouble(double value, boolean increment) {
return increment ? nextDouble(value) : previousDouble(value);
}
/**
* Parses a double from the specified string starting at the index specified
* by {@code position}. The string is compared to the strings of this
* {@code ChoiceFormat} and if a match occurs then the lower bound of the
* corresponding range in the limits array is returned. If the string is
* successfully parsed then the index of the {@code ParsePosition} passed to
* this method is updated to the index following the parsed text.
*
* If one of the format strings of this {@code ChoiceFormat} instance is
* found in {@code string} starting at {@code position.getIndex()} then
*
* - the index in {@code position} is set to the index following the
* parsed text;
*
- the {@link java.lang.Double Double} corresponding to the format
* string is returned.
*
*
* If none of the format strings is found in {@code string} then
*
* - the error index in {@code position} is set to the current index in
* {@code position};
* - {@link java.lang.Double#NaN Double.NaN} is returned.
*
* @param string
* the source string to parse.
* @param position
* input/output parameter, specifies the start index in {@code
* string} from where to start parsing. See the Returns
* section for a description of the output values.
* @return a Double resulting from the parse, or Double.NaN if there is an
* error
*/
@Override
public Number parse(String string, ParsePosition position) {
int offset = position.getIndex();
for (int i = 0; i < choiceFormats.length; i++) {
if (string.startsWith(choiceFormats[i], offset)) {
position.setIndex(offset + choiceFormats[i].length());
return new Double(choiceLimits[i]);
}
}
position.setErrorIndex(offset);
return new Double(Double.NaN);
}
/**
* Returns the double value which is closest to the specified double but
* smaller.
*
* @param value
* a double value.
* @return the next smaller double value.
*/
public static final double previousDouble(double value) {
if (value == Double.NEGATIVE_INFINITY) {
return value;
}
long bits;
// Handle 0.0
if (value == 0) {
bits = 0x8000000000000000L;
} else {
bits = Double.doubleToLongBits(value);
}
return Double.longBitsToDouble(value <= 0 ? bits + 1 : bits - 1);
}
/**
* Sets the double values and associated strings of this ChoiceFormat. When
* calling {@link #format(double, StringBuffer, FieldPosition) format} with
* a double value {@code d}, then the element {@code i} in {@code formats}
* is selected where {@code i} fulfills
* {@code limits[i] <= d < limits[i+1]}.
*
* The length of the {@code limits} and {@code formats} arrays must be the
* same.
*
* @param limits
* an array of doubles in ascending order. The lowest and highest
* possible values are negative and positive infinity.
* @param formats
* the strings associated with the ranges defined through {@code
* limits}. The lower bound of the associated range is at the
* same index as the string.
*/
public void setChoices(double[] limits, String[] formats) {
if (limits.length != formats.length) {
throw new IllegalArgumentException("limits.length != formats.length: " +
limits.length + " != " + formats.length);
}
choiceLimits = limits;
choiceFormats = formats;
}
private int skipWhitespace(String string, int index) {
int length = string.length();
while (index < length && Character.isWhitespace(string.charAt(index))) {
index++;
}
return index;
}
/**
* Returns the pattern of this {@code ChoiceFormat} which specifies the
* ranges and their associated strings.
*
* @return the pattern.
*/
public String toPattern() {
StringBuilder buffer = new StringBuilder();
for (int i = 0; i < choiceLimits.length; i++) {
if (i != 0) {
buffer.append('|');
}
String previous = String.valueOf(previousDouble(choiceLimits[i]));
String limit = String.valueOf(choiceLimits[i]);
if (previous.length() < limit.length()) {
buffer.append(previous);
buffer.append('<');
} else {
buffer.append(limit);
buffer.append('#');
}
boolean quote = (choiceFormats[i].indexOf('|') != -1);
if (quote) {
buffer.append('\'');
}
buffer.append(choiceFormats[i]);
if (quote) {
buffer.append('\'');
}
}
return buffer.toString();
}
}