* A time-zone offset is the amount of time that a time-zone differs from Greenwich/UTC. * This is usually a fixed number of hours and minutes. *
* Different parts of the world have different time-zone offsets. * The rules for how offsets vary by place and time of year are captured in the * {@link ZoneId} class. *
* For example, Paris is one hour ahead of Greenwich/UTC in winter and two hours * ahead in summer. The {@code ZoneId} instance for Paris will reference two * {@code ZoneOffset} instances - a {@code +01:00} instance for winter, * and a {@code +02:00} instance for summer. *
* In 2008, time-zone offsets around the world extended from -12:00 to +14:00. * To prevent any problems with that range being extended, yet still provide * validation, the range of offsets is restricted to -18:00 to 18:00 inclusive. *
* This class is designed for use with the ISO calendar system. * The fields of hours, minutes and seconds make assumptions that are valid for the * standard ISO definitions of those fields. This class may be used with other * calendar systems providing the definition of the time fields matches those * of the ISO calendar system. *
* Instances of {@code ZoneOffset} must be compared using {@link #equals}. * Implementations may choose to cache certain common offsets, however * applications must not rely on such caching. * *
* This is a value-based
* class; use of identity-sensitive operations (including reference equality
* ({@code ==}), identity hash code, or synchronization) on instances of
* {@code ZoneOffset} may have unpredictable results and should be avoided.
* The {@code equals} method should be used for comparisons.
*
* @implSpec
* This class is immutable and thread-safe.
*
* @since 1.8
*/
public final class ZoneOffset
extends ZoneId
implements TemporalAccessor, TemporalAdjuster, Comparable
* This method parses the string ID of a {@code ZoneOffset} to
* return an instance. The parsing accepts all the formats generated by
* {@link #getId()}, plus some additional formats:
*
* The ID of the returned offset will be normalized to one of the formats
* described by {@link #getId()}.
*
* The maximum supported range is from +18:00 to -18:00 inclusive.
*
* @param offsetId the offset ID, not null
* @return the zone-offset, not null
* @throws DateTimeException if the offset ID is invalid
*/
@SuppressWarnings("fallthrough")
public static ZoneOffset of(String offsetId) {
Objects.requireNonNull(offsetId, "offsetId");
// "Z" is always in the cache
ZoneOffset offset = ID_CACHE.get(offsetId);
if (offset != null) {
return offset;
}
// parse - +h, +hh, +hhmm, +hh:mm, +hhmmss, +hh:mm:ss
final int hours, minutes, seconds;
switch (offsetId.length()) {
case 2:
offsetId = offsetId.charAt(0) + "0" + offsetId.charAt(1); // fallthru
case 3:
hours = parseNumber(offsetId, 1, false);
minutes = 0;
seconds = 0;
break;
case 5:
hours = parseNumber(offsetId, 1, false);
minutes = parseNumber(offsetId, 3, false);
seconds = 0;
break;
case 6:
hours = parseNumber(offsetId, 1, false);
minutes = parseNumber(offsetId, 4, true);
seconds = 0;
break;
case 7:
hours = parseNumber(offsetId, 1, false);
minutes = parseNumber(offsetId, 3, false);
seconds = parseNumber(offsetId, 5, false);
break;
case 9:
hours = parseNumber(offsetId, 1, false);
minutes = parseNumber(offsetId, 4, true);
seconds = parseNumber(offsetId, 7, true);
break;
default:
throw new DateTimeException("Invalid ID for ZoneOffset, invalid format: " + offsetId);
}
char first = offsetId.charAt(0);
if (first != '+' && first != '-') {
throw new DateTimeException("Invalid ID for ZoneOffset, plus/minus not found when expected: " + offsetId);
}
if (first == '-') {
return ofHoursMinutesSeconds(-hours, -minutes, -seconds);
} else {
return ofHoursMinutesSeconds(hours, minutes, seconds);
}
}
/**
* Parse a two digit zero-prefixed number.
*
* @param offsetId the offset ID, not null
* @param pos the position to parse, valid
* @param precededByColon should this number be prefixed by a precededByColon
* @return the parsed number, from 0 to 99
*/
private static int parseNumber(CharSequence offsetId, int pos, boolean precededByColon) {
if (precededByColon && offsetId.charAt(pos - 1) != ':') {
throw new DateTimeException("Invalid ID for ZoneOffset, colon not found when expected: " + offsetId);
}
char ch1 = offsetId.charAt(pos);
char ch2 = offsetId.charAt(pos + 1);
if (ch1 < '0' || ch1 > '9' || ch2 < '0' || ch2 > '9') {
throw new DateTimeException("Invalid ID for ZoneOffset, non numeric characters found: " + offsetId);
}
return (ch1 - 48) * 10 + (ch2 - 48);
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code ZoneOffset} using an offset in hours.
*
* @param hours the time-zone offset in hours, from -18 to +18
* @return the zone-offset, not null
* @throws DateTimeException if the offset is not in the required range
*/
public static ZoneOffset ofHours(int hours) {
return ofHoursMinutesSeconds(hours, 0, 0);
}
/**
* Obtains an instance of {@code ZoneOffset} using an offset in
* hours and minutes.
*
* The sign of the hours and minutes components must match.
* Thus, if the hours is negative, the minutes must be negative or zero.
* If the hours is zero, the minutes may be positive, negative or zero.
*
* @param hours the time-zone offset in hours, from -18 to +18
* @param minutes the time-zone offset in minutes, from 0 to ±59, sign matches hours
* @return the zone-offset, not null
* @throws DateTimeException if the offset is not in the required range
*/
public static ZoneOffset ofHoursMinutes(int hours, int minutes) {
return ofHoursMinutesSeconds(hours, minutes, 0);
}
/**
* Obtains an instance of {@code ZoneOffset} using an offset in
* hours, minutes and seconds.
*
* The sign of the hours, minutes and seconds components must match.
* Thus, if the hours is negative, the minutes and seconds must be negative or zero.
*
* @param hours the time-zone offset in hours, from -18 to +18
* @param minutes the time-zone offset in minutes, from 0 to ±59, sign matches hours and seconds
* @param seconds the time-zone offset in seconds, from 0 to ±59, sign matches hours and minutes
* @return the zone-offset, not null
* @throws DateTimeException if the offset is not in the required range
*/
public static ZoneOffset ofHoursMinutesSeconds(int hours, int minutes, int seconds) {
validate(hours, minutes, seconds);
int totalSeconds = totalSeconds(hours, minutes, seconds);
return ofTotalSeconds(totalSeconds);
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code ZoneOffset} from a temporal object.
*
* This obtains an offset based on the specified temporal.
* A {@code TemporalAccessor} represents an arbitrary set of date and time information,
* which this factory converts to an instance of {@code ZoneOffset}.
*
* A {@code TemporalAccessor} represents some form of date and time information.
* This factory converts the arbitrary temporal object to an instance of {@code ZoneOffset}.
*
* The conversion uses the {@link TemporalQueries#offset()} query, which relies
* on extracting the {@link ChronoField#OFFSET_SECONDS OFFSET_SECONDS} field.
*
* This method matches the signature of the functional interface {@link TemporalQuery}
* allowing it to be used as a query via method reference, {@code ZoneOffset::from}.
*
* @param temporal the temporal object to convert, not null
* @return the zone-offset, not null
* @throws DateTimeException if unable to convert to an {@code ZoneOffset}
*/
public static ZoneOffset from(TemporalAccessor temporal) {
Objects.requireNonNull(temporal, "temporal");
ZoneOffset offset = temporal.query(TemporalQueries.offset());
if (offset == null) {
throw new DateTimeException("Unable to obtain ZoneOffset from TemporalAccessor: " +
temporal + " of type " + temporal.getClass().getName());
}
return offset;
}
//-----------------------------------------------------------------------
/**
* Validates the offset fields.
*
* @param hours the time-zone offset in hours, from -18 to +18
* @param minutes the time-zone offset in minutes, from 0 to ±59
* @param seconds the time-zone offset in seconds, from 0 to ±59
* @throws DateTimeException if the offset is not in the required range
*/
private static void validate(int hours, int minutes, int seconds) {
if (hours < -18 || hours > 18) {
throw new DateTimeException("Zone offset hours not in valid range: value " + hours +
" is not in the range -18 to 18");
}
if (hours > 0) {
if (minutes < 0 || seconds < 0) {
throw new DateTimeException("Zone offset minutes and seconds must be positive because hours is positive");
}
} else if (hours < 0) {
if (minutes > 0 || seconds > 0) {
throw new DateTimeException("Zone offset minutes and seconds must be negative because hours is negative");
}
} else if ((minutes > 0 && seconds < 0) || (minutes < 0 && seconds > 0)) {
throw new DateTimeException("Zone offset minutes and seconds must have the same sign");
}
if (minutes < -59 || minutes > 59) {
throw new DateTimeException("Zone offset minutes not in valid range: value " +
minutes + " is not in the range -59 to 59");
}
if (seconds < -59 || seconds > 59) {
throw new DateTimeException("Zone offset seconds not in valid range: value " +
seconds + " is not in the range -59 to 59");
}
if (Math.abs(hours) == 18 && (minutes | seconds) != 0) {
throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
}
}
/**
* Calculates the total offset in seconds.
*
* @param hours the time-zone offset in hours, from -18 to +18
* @param minutes the time-zone offset in minutes, from 0 to ±59, sign matches hours and seconds
* @param seconds the time-zone offset in seconds, from 0 to ±59, sign matches hours and minutes
* @return the total in seconds
*/
private static int totalSeconds(int hours, int minutes, int seconds) {
return hours * SECONDS_PER_HOUR + minutes * SECONDS_PER_MINUTE + seconds;
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code ZoneOffset} specifying the total offset in seconds
*
* The offset must be in the range {@code -18:00} to {@code +18:00}, which corresponds to -64800 to +64800.
*
* @param totalSeconds the total time-zone offset in seconds, from -64800 to +64800
* @return the ZoneOffset, not null
* @throws DateTimeException if the offset is not in the required range
*/
public static ZoneOffset ofTotalSeconds(int totalSeconds) {
if (totalSeconds < -MAX_SECONDS || totalSeconds > MAX_SECONDS) {
throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
}
if (totalSeconds % (15 * SECONDS_PER_MINUTE) == 0) {
Integer totalSecs = totalSeconds;
ZoneOffset result = SECONDS_CACHE.get(totalSecs);
if (result == null) {
result = new ZoneOffset(totalSeconds);
SECONDS_CACHE.putIfAbsent(totalSecs, result);
result = SECONDS_CACHE.get(totalSecs);
ID_CACHE.putIfAbsent(result.getId(), result);
}
return result;
} else {
return new ZoneOffset(totalSeconds);
}
}
//-----------------------------------------------------------------------
/**
* Constructor.
*
* @param totalSeconds the total time-zone offset in seconds, from -64800 to +64800
*/
private ZoneOffset(int totalSeconds) {
super();
this.totalSeconds = totalSeconds;
id = buildId(totalSeconds);
}
private static String buildId(int totalSeconds) {
if (totalSeconds == 0) {
return "Z";
} else {
int absTotalSeconds = Math.abs(totalSeconds);
StringBuilder buf = new StringBuilder();
int absHours = absTotalSeconds / SECONDS_PER_HOUR;
int absMinutes = (absTotalSeconds / SECONDS_PER_MINUTE) % MINUTES_PER_HOUR;
buf.append(totalSeconds < 0 ? "-" : "+")
.append(absHours < 10 ? "0" : "").append(absHours)
.append(absMinutes < 10 ? ":0" : ":").append(absMinutes);
int absSeconds = absTotalSeconds % SECONDS_PER_MINUTE;
if (absSeconds != 0) {
buf.append(absSeconds < 10 ? ":0" : ":").append(absSeconds);
}
return buf.toString();
}
}
//-----------------------------------------------------------------------
/**
* Gets the total zone offset in seconds.
*
* This is the primary way to access the offset amount.
* It returns the total of the hours, minutes and seconds fields as a
* single offset that can be added to a time.
*
* @return the total zone offset amount in seconds
*/
public int getTotalSeconds() {
return totalSeconds;
}
/**
* Gets the normalized zone offset ID.
*
* The ID is minor variation to the standard ISO-8601 formatted string
* for the offset. There are three formats:
*
* The rules will always return this offset when queried.
* The implementation class is immutable, thread-safe and serializable.
*
* @return the rules, not null
*/
@Override
public ZoneRules getRules() {
return ZoneRules.of(this);
}
//-----------------------------------------------------------------------
/**
* Checks if the specified field is supported.
*
* This checks if this offset can be queried for the specified field.
* If false, then calling the {@link #range(TemporalField) range} and
* {@link #get(TemporalField) get} methods will throw an exception.
*
* If the field is a {@link ChronoField} then the query is implemented here.
* The {@code OFFSET_SECONDS} field returns true.
* All other {@code ChronoField} instances will return false.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the field is supported is determined by the field.
*
* @param field the field to check, null returns false
* @return true if the field is supported on this offset, false if not
*/
@Override
public boolean isSupported(TemporalField field) {
if (field instanceof ChronoField) {
return field == OFFSET_SECONDS;
}
return field != null && field.isSupportedBy(this);
}
/**
* Gets the range of valid values for the specified field.
*
* The range object expresses the minimum and maximum valid values for a field.
* This offset is used to enhance the accuracy of the returned range.
* If it is not possible to return the range, because the field is not supported
* or for some other reason, an exception is thrown.
*
* If the field is a {@link ChronoField} then the query is implemented here.
* The {@link #isSupported(TemporalField) supported fields} will return
* appropriate range instances.
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the range can be obtained is determined by the field.
*
* @param field the field to query the range for, not null
* @return the range of valid values for the field, not null
* @throws DateTimeException if the range for the field cannot be obtained
* @throws UnsupportedTemporalTypeException if the field is not supported
*/
@Override // override for Javadoc
public ValueRange range(TemporalField field) {
return TemporalAccessor.super.range(field);
}
/**
* Gets the value of the specified field from this offset as an {@code int}.
*
* This queries this offset for the value of the specified field.
* The returned value will always be within the valid range of values for the field.
* If it is not possible to return the value, because the field is not supported
* or for some other reason, an exception is thrown.
*
* If the field is a {@link ChronoField} then the query is implemented here.
* The {@code OFFSET_SECONDS} field returns the value of the offset.
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained or
* the value is outside the range of valid values for the field
* @throws UnsupportedTemporalTypeException if the field is not supported or
* the range of values exceeds an {@code int}
* @throws ArithmeticException if numeric overflow occurs
*/
@Override // override for Javadoc and performance
public int get(TemporalField field) {
if (field == OFFSET_SECONDS) {
return totalSeconds;
} else if (field instanceof ChronoField) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return range(field).checkValidIntValue(getLong(field), field);
}
/**
* Gets the value of the specified field from this offset as a {@code long}.
*
* This queries this offset for the value of the specified field.
* If it is not possible to return the value, because the field is not supported
* or for some other reason, an exception is thrown.
*
* If the field is a {@link ChronoField} then the query is implemented here.
* The {@code OFFSET_SECONDS} field returns the value of the offset.
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained
* @throws UnsupportedTemporalTypeException if the field is not supported
* @throws ArithmeticException if numeric overflow occurs
*/
@Override
public long getLong(TemporalField field) {
if (field == OFFSET_SECONDS) {
return totalSeconds;
} else if (field instanceof ChronoField) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return field.getFrom(this);
}
//-----------------------------------------------------------------------
/**
* Queries this offset using the specified query.
*
* This queries this offset using the specified query strategy object.
* The {@code TemporalQuery} object defines the logic to be used to
* obtain the result. Read the documentation of the query to understand
* what the result of this method will be.
*
* The result of this method is obtained by invoking the
* {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
* specified query passing {@code this} as the argument.
*
* @param
* This returns a temporal object of the same observable type as the input
* with the offset changed to be the same as this.
*
* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
* passing {@link ChronoField#OFFSET_SECONDS} as the field.
*
* In most cases, it is clearer to reverse the calling pattern by using
* {@link Temporal#with(TemporalAdjuster)}:
*
* This instance is immutable and unaffected by this method call.
*
* @param temporal the target object to be adjusted, not null
* @return the adjusted object, not null
* @throws DateTimeException if unable to make the adjustment
* @throws ArithmeticException if numeric overflow occurs
*/
@Override
public Temporal adjustInto(Temporal temporal) {
return temporal.with(OFFSET_SECONDS, totalSeconds);
}
//-----------------------------------------------------------------------
/**
* Compares this offset to another offset in descending order.
*
* The offsets are compared in the order that they occur for the same time
* of day around the world. Thus, an offset of {@code +10:00} comes before an
* offset of {@code +09:00} and so on down to {@code -18:00}.
*
* The comparison is "consistent with equals", as defined by {@link Comparable}.
*
* @param other the other date to compare to, not null
* @return the comparator value, negative if less, positive if greater
* @throws NullPointerException if {@code other} is null
*/
@Override
public int compareTo(ZoneOffset other) {
// abs(totalSeconds) <= MAX_SECONDS, so no overflow can happen here
return other.totalSeconds - totalSeconds;
}
//-----------------------------------------------------------------------
/**
* Checks if this offset is equal to another offset.
*
* The comparison is based on the amount of the offset in seconds.
* This is equivalent to a comparison by ID.
*
* @param obj the object to check, null returns false
* @return true if this is equal to the other offset
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof ZoneOffset) {
return totalSeconds == ((ZoneOffset) obj).totalSeconds;
}
return false;
}
/**
* A hash code for this offset.
*
* @return a suitable hash code
*/
@Override
public int hashCode() {
return totalSeconds;
}
//-----------------------------------------------------------------------
/**
* Outputs this offset as a {@code String}, using the normalized ID.
*
* @return a string representation of this offset, not null
*/
@Override
public String toString() {
return id;
}
// -----------------------------------------------------------------------
/**
* Writes the object using a
* dedicated serialized form.
* @serialData
*
*
* Note that ± means either the plus or minus symbol.
*
*
*
* @return the zone offset ID, not null
*/
@Override
public String getId() {
return id;
}
/**
* Gets the associated time-zone rules.
*
* // these two lines are equivalent, but the second approach is recommended
* temporal = thisOffset.adjustInto(temporal);
* temporal = temporal.with(thisOffset);
*
*
* out.writeByte(8); // identifies a ZoneOffset
* int offsetByte = totalSeconds % 900 == 0 ? totalSeconds / 900 : 127;
* out.writeByte(offsetByte);
* if (offsetByte == 127) {
* out.writeInt(totalSeconds);
* }
*
*
* @return the instance of {@code Ser}, not null
*/
private Object writeReplace() {
return new Ser(Ser.ZONE_OFFSET_TYPE, this);
}
/**
* Defend against malicious streams.
*
* @param s the stream to read
* @throws InvalidObjectException always
*/
private void readObject(ObjectInputStream s) throws InvalidObjectException {
throw new InvalidObjectException("Deserialization via serialization delegate");
}
@Override
void write(DataOutput out) throws IOException {
out.writeByte(Ser.ZONE_OFFSET_TYPE);
writeExternal(out);
}
void writeExternal(DataOutput out) throws IOException {
final int offsetSecs = totalSeconds;
int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127; // compress to -72 to +72
out.writeByte(offsetByte);
if (offsetByte == 127) {
out.writeInt(offsetSecs);
}
}
static ZoneOffset readExternal(DataInput in) throws IOException {
int offsetByte = in.readByte();
return (offsetByte == 127 ? ZoneOffset.ofTotalSeconds(in.readInt()) : ZoneOffset.ofTotalSeconds(offsetByte * 900));
}
}