ucar.units.OffsetUnit Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of udunits Show documentation
Show all versions of udunits Show documentation
The ucar.units Java package is for decoding and encoding formatted unit specifications (e.g. "m/s"), converting numeric values between compatible units (e.g. between "m/s" and "knot"), and for performing arithmetic operations on units (e.g. dividing one unit by another, or raising a unit to a power).
The newest version!
/*
* Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata
* See LICENSE for license information.
*/
package ucar.units;
import javax.annotation.concurrent.Immutable;
/**
* Provides support for units that are offset from reference units (ex: as the
* unit "degree Celsius" is offset from the reference unit "kelvin"). Instances
* of this class are immutable.
*
* @author Steven R. Emmerson
*/
@Immutable
public final class OffsetUnit extends UnitImpl implements DerivableUnit {
private static final long serialVersionUID = 1L;
/**
* The origin of this unit in terms of the reference unit.
*
* @serial
*/
private final double _offset;
/**
* The reference unit.
*
* @serial
*/
private final Unit _unit;
/**
* The derived unit that is convertible with this unit.
*
* @serial
*/
private final DerivedUnit _derivedUnit;
/**
* Constructs from a reference unit and an offset.
*
* @param unit
* The reference unit.
* @param offset
* The origin of this unit in terms of the reference unit. For
* example, a degree Celsius unit would be created as "new
* OffsetUnit(kelvin, 273.15).
*/
public OffsetUnit(final Unit unit, final double offset) {
this(unit, offset, null);
}
/**
* Constructs from a reference unit, and offset, and a unit identifier.
*
* @param unit
* The reference unit.
* @param offset
* The origin of this unit in terms of the reference unit. For
* example, a degree Celsius unit would be created as "new
* OffsetUnit(kelvin, 273.15).
* @param id
* The identifier for the new unit.
*/
public OffsetUnit(final Unit unit, final double offset, final UnitName id) {
super(id);
if (!(unit instanceof OffsetUnit)) {
_unit = unit;
_offset = offset;
}
else {
_unit = ((OffsetUnit) unit)._unit;
_offset = ((OffsetUnit) unit)._offset + offset;
}
_derivedUnit = _unit.getDerivedUnit();
}
static Unit getInstance(final Unit unit, final double origin) {
return (origin == 0)
? unit
: new OffsetUnit(unit, origin);
}
/**
* Returns the reference unit.
*
* @return The reference unit.
*/
public Unit getUnit() {
return _unit;
}
/**
* Returns the offset. The offset is the location of the origin of this unit
* in terms of the reference unit.
*
* @return The origin of this unit in terms of the reference unit.
*/
public double getOffset() {
return _offset;
}
/*
* From UnitImpl:
*/
/**
* Clones this unit, changing the identifier.
*
* @param id
* The identifier for the new unit.
* @return This unit with its identifier changed.
*/
public Unit clone(final UnitName id) {
return new OffsetUnit(getUnit(), getOffset(), id);
}
@Override
public Unit multiplyBy(final double scale) throws MultiplyException {
if (scale == 0) {
throw new MultiplyException(scale, this);
}
return getInstance(_unit.multiplyBy(scale), _offset / scale);
}
@Override
public Unit shiftTo(final double origin) {
return getInstance(_unit, origin + _offset);
}
/**
* Multiply this unit by another unit.
*
* @param that
* The unit to multiply this unit by.
* @return The product of this unit and that. The offset of
* this unit will be ignored; thus, for example
* "celsius.myMultiplyBy(day)" is equivalent to
* "kelvin.myMultiplyBy(day)".
* @throws MultiplyException
* Can't multiply these units together.
*/
@Override
protected Unit myMultiplyBy(final Unit that) throws MultiplyException {
return that instanceof OffsetUnit
? getUnit().multiplyBy(((OffsetUnit) that).getUnit())
: getUnit().multiplyBy(that);
}
/**
* Divide this unit by another unit.
*
* @param that
* The unit to divide this unit by.
* @return The quotient of this unit and that. The offset of
* this unit will be ignored; thus, for example
* "celsius.myDivideBy(day)" is equivalent to
* "kelvin.myDivideBy(day)".
* @throws OperationException
* Can't divide these units.
*/
@Override
protected Unit myDivideBy(final Unit that) throws OperationException {
return that instanceof OffsetUnit
? getUnit().divideBy(((OffsetUnit) that).getUnit())
: getUnit().divideBy(that);
}
/**
* Divide this unit into another unit.
*
* @param that
* The unit to divide this unit into.
* @return The quotient of that unit and this unit. The offset
* of this unit will be ignored; thus, for example
* "celsius.myDivideInto(day)" is equivalent to
* "kelvin.myDivideInto(day)".
* @throws OperationException
* Can't divide these units.
*/
@Override
protected Unit myDivideInto(final Unit that) throws OperationException {
return that instanceof OffsetUnit
? getUnit().divideInto(((OffsetUnit) that).getUnit())
: getUnit().divideInto(that);
}
/**
* Raise this unit to a power.
*
* @param power
* The power to raise this unit by.
* @return The result of raising this unit by the power power.
* The offset of this unit will be ignored; thus, for example
* "celsius.myRaiseTo(2)" is equivalent to "kelvin.myRaiseTo(2)".
* @throws RaiseException
* Can't raise this unit to a power.
*/
// Ignore offset (e.g. "Cel2" == "K2")
@Override
protected Unit myRaiseTo(final int power) throws RaiseException {
return getUnit().raiseTo(power);
}
/**
* Returns the derived unit that is convertible with this unit.
*
* @return The derived unit that is convertible with this unit.
*/
public DerivedUnit getDerivedUnit() {
return _derivedUnit;
}
/**
* Converts a value in this unit to the equivalent value in the convertible
* derived unit.
*
* @param amount
* The value in this unit.
* @return The equivalent value in the convertible derived unit.
* @throws ConversionException
* Can't convert between units.
*/
public float toDerivedUnit(final float amount) throws ConversionException {
return (float) toDerivedUnit((double) amount);
}
/**
* Converts a value in this unit to the equivalent value in the convertible
* derived unit.
*
* @param amount
* The value in this unit.
* @return The equivalent value in the convertible derived unit.
* @throws ConversionException
* Can't convert between units.
*/
public double toDerivedUnit(final double amount) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
return ((DerivableUnit) getUnit()).toDerivedUnit(amount + getOffset());
}
/**
* Converts values in this unit to the equivalent values in the convertible
* derived unit.
*
* @param input
* The values in this unit.
* @param output
* The equivalent values in the convertible derived unit. May be
* the same array as input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public float[] toDerivedUnit(final float[] input, final float[] output)
throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
final float origin = (float) getOffset();
for (int i = input.length; --i >= 0;) {
output[i] = input[i] + origin;
}
return ((DerivableUnit) getUnit()).toDerivedUnit(output, output);
}
/**
* Converts values in this unit to the equivalent values in the convertible
* derived unit.
*
* @param input
* The values in this unit.
* @param output
* The equivalent values in the convertible derived unit. May be
* the same array as input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public double[] toDerivedUnit(final double[] input, final double[] output)
throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
final double origin = getOffset();
for (int i = input.length; --i >= 0;) {
output[i] = input[i] + origin;
}
return ((DerivableUnit) getUnit()).toDerivedUnit(output, output);
}
/**
* Converts a value in the convertible derived unit to the equivalent value
* in this unit.
*
* @param amount
* The value in the convertible derived unit.
* @return The equivalent value in this unit.
* @throws ConversionException
* Can't convert between units.
*/
public float fromDerivedUnit(final float amount) throws ConversionException {
return (float) fromDerivedUnit((double) amount);
}
/**
* Converts a value in the convertible derived unit to the equivalent value
* in this unit.
*
* @param amount
* The value in the convertible derived unit.
* @return The equivalent value in this unit.
* @throws ConversionException
* Can't convert between units.
*/
public double fromDerivedUnit(final double amount)
throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
return ((DerivableUnit) getUnit()).fromDerivedUnit(amount)
- getOffset();
}
/**
* Converts values in the convertible derived unit to the equivalent values
* in this unit.
*
* @param input
* The values in the convertible derived unit.
* @param output
* The equivalent values in this unit. May be the same array as
* input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public float[] fromDerivedUnit(final float[] input, final float[] output)
throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
((DerivableUnit) getUnit()).fromDerivedUnit(input, output);
final float origin = (float) getOffset();
for (int i = input.length; --i >= 0;) {
output[i] -= origin;
}
return output;
}
/**
* Converts values in the convertible derived unit to the equivalent values
* in this unit.
*
* @param input
* The values in the convertible derived unit.
* @param output
* The equivalent values in this unit. May be the same array as
* input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public double[] fromDerivedUnit(final double[] input, final double[] output)
throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
((DerivableUnit) getUnit()).fromDerivedUnit(input, output);
final double origin = getOffset();
for (int i = input.length; --i >= 0;) {
output[i] -= origin;
}
return output;
}
/**
* Indicates if this unit is semantically identical to an object.
*
* @param object
* The object.
* @return true if and only if this unit is semantically
* identical to object
* .
*/
@Override
public boolean equals(final Object object) {
if (this == object) {
return true;
}
if (_offset == 0) {
return object.equals(_unit);
}
if (!(object instanceof OffsetUnit)) {
return false;
}
OffsetUnit that = (OffsetUnit) object;
if (Double.compare(that._offset, _offset) != 0) return false;
return _unit.equals(that._unit);
}
/**
* Returns the hash code of this instance.
*
* @return The hash code of this instance.
*/
@Override
public int hashCode() {
return (getOffset() == 0
? 0
: Double.valueOf(getOffset()).hashCode())
^ getUnit().hashCode();
}
/**
* Indicates if this unit is dimensionless.
*
* @return true if and only if this unit is dimensionless.
*/
public boolean isDimensionless() {
return getUnit().isDimensionless();
}
/**
* Returns the string representation of this unit.
*
* @return The string representation of this unit.
*/
@Override
public String toString() {
final String string = super.toString(); // get symbol or name
return string != null
? string
: getCanonicalString();
}
/**
* Returns the canonical string representation of the unit.
*
* @return The canonical string representation.
*/
public String getCanonicalString() {
return "(" + getUnit().toString() + ") @ " + getOffset();
}
}