| 1 | /* |
| 2 | * JScience - Java(TM) Tools and Libraries for the Advancement of Sciences. |
| 3 | * Copyright (C) 2006 - JScience (http://jscience.org/) |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * Permission to use, copy, modify, and distribute this software is |
| 7 | * freely granted, provided that this notice is preserved. |
| 8 | */ |
| 9 | package javax.measure.converter; |
| 10 | |
| 11 | /** |
| 12 | * <p> This class represents a converter multiplying numeric values by a |
| 13 | * constant scaling factor (approximated as a <code>double</code>). |
| 14 | * For exact scaling conversions {@link RationalConverter} is preferred.</p> |
| 15 | * |
| 16 | * <p> Instances of this class are immutable.</p> |
| 17 | * |
| 18 | * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a> |
| 19 | * @version 3.1, April 22, 2006 |
| 20 | */ |
| 21 | public final class MultiplyConverter extends UnitConverter { |
| 22 | |
| 23 | /** |
| 24 | * Holds the scale factor. |
| 25 | */ |
| 26 | private final double _factor; |
| 27 | |
| 28 | /** |
| 29 | * Creates a multiply converter with the specified scale factor. |
| 30 | * |
| 31 | * @param factor the scale factor. |
| 32 | * @throws IllegalArgumentException if offset is one (or close to one). |
| 33 | */ |
| 34 | public MultiplyConverter(double factor) { |
| 35 | if ((float)factor == 1.0) |
| 36 | throw new IllegalArgumentException("Identity converter not allowed"); |
| 37 | _factor = factor; |
| 38 | } |
| 39 | |
| 40 | /** |
| 41 | * Returns the scale factor. |
| 42 | * |
| 43 | * @return the scale factor. |
| 44 | */ |
| 45 | public double getFactor() { |
| 46 | return _factor; |
| 47 | } |
| 48 | |
| 49 | @Override |
| 50 | public UnitConverter inverse() { |
| 51 | return new MultiplyConverter(1.0 / _factor); |
| 52 | } |
| 53 | |
| 54 | @Override |
| 55 | public double convert(double amount) { |
| 56 | return _factor * amount; |
| 57 | } |
| 58 | |
| 59 | @Override |
| 60 | public boolean isLinear() { |
| 61 | return true; |
| 62 | } |
| 63 | |
| 64 | @Override |
| 65 | public UnitConverter concatenate(UnitConverter converter) { |
| 66 | if (converter instanceof MultiplyConverter) { |
| 67 | double factor = _factor * ((MultiplyConverter) converter)._factor; |
| 68 | return valueOf(factor); |
| 69 | } else if (converter instanceof RationalConverter) { |
| 70 | double factor = _factor |
| 71 | * ((RationalConverter) converter).getDividend() |
| 72 | / ((RationalConverter) converter).getDivisor(); |
| 73 | return valueOf(factor); |
| 74 | } else { |
| 75 | return super.concatenate(converter); |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | private static UnitConverter valueOf(double factor) { |
| 80 | float asFloat = (float) factor; |
| 81 | return asFloat == 1.0f ? UnitConverter.IDENTITY |
| 82 | : new MultiplyConverter(factor); |
| 83 | } |
| 84 | |
| 85 | private static final long serialVersionUID = 1L; |
| 86 | } |