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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).
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/*
* 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 a unit that is a mutiplicative factor of a reference
* unit.
*
* Instances of this class are immutable.
*
* @author Steven R. Emmerson
*/
@Immutable
public final class ScaledUnit extends UnitImpl implements DerivableUnit {
private static final long serialVersionUID = 1L;
/**
* The multiplicative factor.
*
* @serial
*/
private final double _scale;
/**
* The reference unit.
*
* @serial
*/
private final Unit _unit;
/**
* Constructs from a multiplicative factor. Returns a dimensionless unit
* whose value is the multiplicative factor rather than unity.
*
* @param scale
* The multiplicative factor.
*/
public ScaledUnit(final double scale) {
this(scale, DerivedUnitImpl.DIMENSIONLESS);
}
/**
* Constructs from a multiplicative factor and a reference unit.
*
* @param scale
* The multiplicative factor.
* @param unit
* The reference unit.
*/
public ScaledUnit(final double scale, final Unit unit) {
this(scale, unit, null);
}
/**
* Constructs from a multiplicative factor, a reference unit, and an
* identifier.
*
* @param scale
* The multiplicative factor.
* @param unit
* The reference unit.
* @param id
* The identifier for the unit.
*/
public ScaledUnit(final double scale, final Unit unit, final UnitName id) {
super(id);
if (!(unit instanceof ScaledUnit)) {
_unit = unit;
_scale = scale;
}
else {
_unit = ((ScaledUnit) unit)._unit;
_scale = ((ScaledUnit) unit)._scale * scale;
}
}
static Unit getInstance(final double scale, final Unit unit)
throws MultiplyException {
if (scale == 0) {
throw new MultiplyException(scale, unit);
}
return scale == 1
? unit
: new ScaledUnit(scale, unit);
}
/**
* Returns the multiplicative factor.
*
* @return The multiplicative factor.
*/
public double getScale() {
return _scale;
}
/**
* Returns the reference unit.
*
* @return The reference unit.
*/
public Unit getUnit() {
return _unit;
}
/*
* From UnitImpl:
*/
/**
* Clones this unit, changing the identifier.
*
* @param id
* The new identifier.
* @return A ScaledUnit with the new identifier.
*/
public Unit clone(final UnitName id) {
return new ScaledUnit(_scale, getUnit(), id);
}
@Override
public Unit multiplyBy(final double scale) throws MultiplyException {
return getInstance(scale * _scale, _unit);
}
/**
* Multiplies this unit by another unit.
*
* @param that
* The other unit.
* @return The product of this unit and the other unit.
* @throws MultiplyException
* Can't multiply these units together.
*/
@Override
protected Unit myMultiplyBy(final Unit that) throws MultiplyException {
return that instanceof ScaledUnit
? new ScaledUnit(getScale() * ((ScaledUnit) that).getScale(),
getUnit().multiplyBy(((ScaledUnit) that).getUnit()))
: new ScaledUnit(getScale(), getUnit().multiplyBy(that));
}
/**
* Divides this unit by another unit.
*
* @param that
* The other unit.
* @return The quotient of this unit divided by the other unit.
* @throws OperationException
* Can't divide these units.
*/
@Override
protected Unit myDivideBy(final Unit that) throws OperationException {
return that instanceof ScaledUnit
? new ScaledUnit(getScale() / ((ScaledUnit) that).getScale(),
getUnit().divideBy(((ScaledUnit) that).getUnit()))
: new ScaledUnit(getScale(), getUnit().divideBy(that));
}
/**
* Divides this unit into another unit.
*
* @param that
* The other unit.
* @return The quotient of this unit divided into the other unit.
* @throws OperationException
* Can't divide these units.
*/
@Override
protected Unit myDivideInto(final Unit that) throws OperationException {
return that instanceof ScaledUnit
? new ScaledUnit(((ScaledUnit) that).getScale() / getScale(),
getUnit().divideInto(((ScaledUnit) that).getUnit()))
: new ScaledUnit(1 / getScale(), getUnit().divideInto(that));
}
/**
* Raises this unit to a power.
*
* @param power
* The power.
* @return The result of raising this unit to the power.
* @throws RaiseException
* Can't raise this unit to a power.
*/
@Override
protected Unit myRaiseTo(final int power) throws RaiseException {
return new ScaledUnit(Math.pow(getScale(), power), getUnit().raiseTo(
power));
}
/**
* Gets the derived unit underlying this unit.
*
* @return The derived unit which underlies this unit.
*/
public DerivedUnit getDerivedUnit() {
return getUnit().getDerivedUnit();
}
/**
* Converts a numeric value from this unit to the underlying derived unit.
*
* @param amount
* The numeric value in this unit.
* @return The equivalent value in the underlying derived unit.
* @throws ConversionException
* Can't convert value to the underlying derived unit.
*/
public float toDerivedUnit(final float amount) throws ConversionException {
return (float) toDerivedUnit((double) amount);
}
/**
* Converts a numeric value from this unit to the underlying derived unit.
*
* @param amount
* The numeric value in this unit.
* @return The equivalent value in the underlying derived unit.
* @throws ConversionException
* Can't convert value to the underlying derived unit.
*/
public double toDerivedUnit(final double amount) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
return ((DerivableUnit) _unit).toDerivedUnit(amount * getScale());
}
/**
* Converts numeric values from this unit to the underlying derived unit.
*
* @param input
* The numeric values in this unit.
* @param output
* The equivalent values in the underlying derived unit.
* @return output.
* @throws ConversionException
* Can't convert values to the underlying derived unit.
*/
public float[] toDerivedUnit(final float[] input, final float[] output)
throws ConversionException {
final float scale = (float) getScale();
for (int i = input.length; --i >= 0;) {
output[i] = input[i] * scale;
}
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
return ((DerivableUnit) getUnit()).toDerivedUnit(output, output);
}
/**
* Converts numeric values from this unit to the underlying derived unit.
*
* @param input
* The numeric values in this unit.
* @param output
* The equivalent values in the underlying derived unit.
* @return output.
* @throws ConversionException
* Can't convert values to the underlying derived unit.
*/
public double[] toDerivedUnit(final double[] input, final double[] output)
throws ConversionException {
final double scale = getScale();
for (int i = input.length; --i >= 0;) {
output[i] = input[i] * scale;
}
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
return ((DerivableUnit) getUnit()).toDerivedUnit(output, output);
}
/**
* Converts a numeric value from the underlying derived unit to this unit.
*
* @param amount
* The numeric value in the underlying derived unit.
* @return The equivalent value in this unit.
* @throws ConversionException
* Can't convert value.
*/
public float fromDerivedUnit(final float amount) throws ConversionException {
return (float) fromDerivedUnit((double) amount);
}
/**
* Converts a numeric value from the underlying derived unit to this unit.
*
* @param amount
* The numeric value in the underlying derived unit.
* @return The equivalent value in this unit.
* @throws ConversionException
* Can't convert value.
*/
public double fromDerivedUnit(final double amount)
throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
return ((DerivableUnit) getUnit()).fromDerivedUnit(amount) / getScale();
}
/**
* Converts numeric values from the underlying derived unit to this unit.
*
* @param input
* The numeric values in the underlying derived unit.
* @param output
* The equivalent values in this unit.
* @return output.
* @throws ConversionException
* Can't convert values.
*/
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 scale = (float) getScale();
for (int i = input.length; --i >= 0;) {
output[i] /= scale;
}
return output;
}
/**
* Converts numeric values from the underlying derived unit to this unit.
*
* @param input
* The numeric values in the underlying derived unit.
* @param output
* The equivalent values in this unit.
* @return output.
* @throws ConversionException
* Can't convert values.
*/
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 scale = getScale();
for (int i = input.length; --i >= 0;) {
output[i] /= scale;
}
return output;
}
/**
* Indicates if this unit is semantically identical to an object.
*
* @param object
* The object.
* @return true if an only if this unit is semantically
* identical to object
* .
*/
public boolean equals(final Object object) {
if (this == object) {
return true;
}
if (_scale == 1) {
return object.equals(_unit);
}
if (!(object instanceof ScaledUnit)) {
return false;
}
ScaledUnit that = (ScaledUnit) object;
if (Double.compare(that._scale, _scale) != 0) return false;
if (!_unit.equals(that._unit)) return false;
return true;
}
/**
* Returns the hash code of this instance.
*
* @return The hash code of this instance.
*/
@Override
public int hashCode() {
return (getScale() == 1
? 0
: Double.valueOf(getScale()).hashCode()) ^ getUnit().hashCode();
}
/**
* Indicates if this unit is dimensionless. A ScaledUnit is dimensionless if
* and only if the reference 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 DerivedUnitImpl.DIMENSIONLESS.equals(_unit)
? Double.toString(getScale())
: Double.toString(getScale()) + " " + _unit.toString();
}
/**
* Tests this class.
*/
public static void main(final String[] args) throws Exception {
final BaseUnit meter = BaseUnit.getOrCreate(UnitName.newUnitName(
"meter", null, "m"), BaseQuantity.LENGTH);
final ScaledUnit nauticalMile = new ScaledUnit(1852f, meter);
System.out.println("nauticalMile.getUnit().equals(meter)="
+ nauticalMile.getUnit().equals(meter));
final ScaledUnit nauticalMileMeter = (ScaledUnit) nauticalMile
.multiplyBy(meter);
System.out.println("nauticalMileMeter.divideBy(nauticalMile)="
+ nauticalMileMeter.divideBy(nauticalMile));
System.out.println("meter.divideBy(nauticalMile)="
+ meter.divideBy(nauticalMile));
System.out
.println("nauticalMile.raiseTo(2)=" + nauticalMile.raiseTo(2));
System.out.println("nauticalMile.toDerivedUnit(1.)="
+ nauticalMile.toDerivedUnit(1.));
System.out
.println("nauticalMile.toDerivedUnit(new float[]{1,2,3}, new float[3])[1]="
+ nauticalMile.toDerivedUnit(new float[] { 1, 2, 3 },
new float[3])[1]);
System.out.println("nauticalMile.fromDerivedUnit(1852.)="
+ nauticalMile.fromDerivedUnit(1852.));
System.out
.println("nauticalMile.fromDerivedUnit(new float[]{1852},new float[1])[0]="
+ nauticalMile.fromDerivedUnit(new float[] { 1852 },
new float[1])[0]);
System.out.println("nauticalMile.equals(nauticalMile)="
+ nauticalMile.equals(nauticalMile));
final ScaledUnit nautical2Mile = new ScaledUnit(2, nauticalMile);
System.out.println("nauticalMile.equals(nautical2Mile)="
+ nauticalMile.equals(nautical2Mile));
System.out.println("nauticalMile.isDimensionless()="
+ nauticalMile.isDimensionless());
final BaseUnit radian = BaseUnit.getOrCreate(UnitName.newUnitName(
"radian", null, "rad"), BaseQuantity.PLANE_ANGLE);
final ScaledUnit degree = new ScaledUnit(3.14159 / 180, radian);
System.out.println("degree.isDimensionless()="
+ degree.isDimensionless());
}
}