Java Code Examples for javax.measure.Quantity#getUnit()

/**
 * Returns the given quantity as an instance of the specific {@code Quantity} subtype.
 * For example this method can be used for converting a {@code Quantity<Length>} to a {@link Length}.
 * If the given quantity already implements the specific interface, then it is returned as-is.
 *
 * @param  <Q>      the quantity type (e.g. {@link Length}, {@link Angle}, {@link Time}, <i>etc.</i>), or {@code null}.
 * @param  quantity the quantity to convert to the specific subtype.
 * @return the given quantity as a specific subtype (may be {@code quantity} itself), or {@code null} if the given quantity was null.
 * @throws IllegalArgumentException if the unit class associated to the given quantity is not a supported implementation.
 */
@SuppressWarnings("unchecked")
public static <Q extends Quantity<Q>> Q castOrCopy(final Quantity<Q> quantity) {
    if (quantity != null) {
        final Unit<Q> unit   = quantity.getUnit();
        final Unit<Q> system = unit.getSystemUnit();
        if (!(system instanceof SystemUnit<?>)) {
            throw new IllegalArgumentException(Errors.format(Errors.Keys.UnsupportedImplementation_1, unit.getClass()));
        }
        final Class<Q> type = ((SystemUnit<Q>) system).quantity;
        if (!type.isInstance(quantity)) {
            final ScalarFactory<Q> factory = ((SystemUnit<Q>) system).factory;
            final double value = AbstractConverter.doubleValue(quantity.getValue());
            if (factory != null) {
                return factory.create(value, unit);
            } else {
                return ScalarFallback.factory(value, unit, type);
            }
        }
    }
    return (Q) quantity;
}
 

/**
 * A utility method to parse a unit symbol either directly or from a given pattern (like stateDescription or widget
 * label). In the latter case, the unit is expected to be the last part of the pattern separated by " " (e.g. "%.2f
 * °C" for °C).
 *
 * @param stringWithUnit the string to extract the unit symbol from
 * @return the unit symbol extracted from the string or {@code null} if no unit could be parsed
 *
 */
public static @Nullable Unit<?> parseUnit(@Nullable String pattern) {
    if (pattern == null || pattern.isBlank()) {
        return null;
    }

    String unitSymbol = pattern;
    int lastBlankIndex = pattern.lastIndexOf(" ");
    if (lastBlankIndex >= 0) {
        unitSymbol = pattern.substring(lastBlankIndex).trim();
    }

    if (!UNIT_PLACEHOLDER.equals(unitSymbol)) {
        if (UNIT_PERCENT_FORMAT_STRING.equals(unitSymbol)) {
            return SmartHomeUnits.PERCENT;
        }
        try {
            Quantity<?> quantity = Quantities.getQuantity("1 " + unitSymbol);
            return quantity.getUnit();
        } catch (IllegalArgumentException e) {
            // we expect this exception in case the extracted string does not match any known unit
            LOGGER.debug("Unknown unit from pattern: {}", unitSymbol);
        }
    }

    return null;
}
 

/**
 * A utility method to parse a unit symbol either directly or from a given pattern (like stateDescription or widget
 * label). In the latter case, the unit is expected to be the last part of the pattern separated by " " (e.g. "%.2f
 * °C" for °C).
 *
 * @param stringWithUnit the string to extract the unit symbol from
 * @return the unit symbol extracted from the string or {@code null} if no unit could be parsed
 *
 */
public static @Nullable Unit<?> parseUnit(String pattern) {
    if (StringUtils.isBlank(pattern)) {
        return null;
    }

    String unitSymbol = pattern;
    int lastBlankIndex = pattern.lastIndexOf(" ");
    if (lastBlankIndex >= 0) {
        unitSymbol = pattern.substring(lastBlankIndex).trim();
    }

    if (StringUtils.isNotBlank(unitSymbol) && !unitSymbol.equals(UNIT_PLACEHOLDER)) {
        if (UNIT_PERCENT_FORMAT_STRING.equals(unitSymbol)) {
            return SmartHomeUnits.PERCENT;
        }
        try {
            Quantity<?> quantity = Quantities.getQuantity("1 " + unitSymbol);
            return quantity.getUnit();
        } catch (IllegalArgumentException e) {
            // we expect this exception in case the extracted string does not match any known unit
            LOGGER.debug("Unknown unit from pattern: {}", unitSymbol);
        }
    }

    return null;
}
 

/**
 * Returns the value of the given quantity converted to the same units of measurement than this quantity.
 */
private double doubleValue(final Quantity<Q> other) {
    double otherValue = other.getValue().doubleValue();
    final Unit<Q> otherUnit = other.getUnit();
    if (otherUnit != unit) {
        otherValue = otherUnit.getConverterTo(unit).convert(otherValue);
    }
    return otherValue;
}
 

@Override
protected Object[] toConvertedColumns(Quantity<?> value) {
    return new Object[] { value.getValue().toString(), value.getUnit() };
}