Java tutorial
/** * Copyright 2014 Andreas Schildbach * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.neoscoinj.utils; import static com.google.common.base.Preconditions.checkArgument; import java.io.Serializable; import java.math.BigDecimal; import org.neoscoinj.core.Monetary; import com.google.common.math.LongMath; /** * Represents a monetary fiat value. It was decided to not fold this into {@link Coin} because of type safety. Fiat * values always come with an attached currency code. * * This class is immutable. */ public final class Fiat implements Monetary, Comparable<Fiat>, Serializable { /** * The absolute value of exponent of the value of a "smallest unit" in scientific notation. We picked 4 rather than * 2, because in financial applications it's common to use sub-cent precision. */ public static final int SMALLEST_UNIT_EXPONENT = 4; /** * The number of smallest units of this monetary value. */ public final long value; public final String currencyCode; private Fiat(final String currencyCode, final long value) { this.value = value; this.currencyCode = currencyCode; } public static Fiat valueOf(final String currencyCode, final long value) { return new Fiat(currencyCode, value); } @Override public int smallestUnitExponent() { return SMALLEST_UNIT_EXPONENT; } /** * Returns the number of "smallest units" of this monetary value. */ @Override public long getValue() { return value; } public String getCurrencyCode() { return currencyCode; } /** * Parses an amount expressed in the way humans are used to. * <p> * <p/> * This takes string in a format understood by {@link BigDecimal#BigDecimal(String)}, for example "0", "1", "0.10", * "1.23E3", "1234.5E-5". * * @throws IllegalArgumentException * if you try to specify fractional satoshis, or a value out of range. */ public static Fiat parseFiat(final String currencyCode, final String str) { try { long val = new BigDecimal(str).movePointRight(SMALLEST_UNIT_EXPONENT).toBigIntegerExact().longValue(); return Fiat.valueOf(currencyCode, val); } catch (ArithmeticException e) { throw new IllegalArgumentException(e); } } public Fiat add(final Fiat value) { checkArgument(value.currencyCode.equals(currencyCode)); return new Fiat(currencyCode, LongMath.checkedAdd(this.value, value.value)); } public Fiat subtract(final Fiat value) { checkArgument(value.currencyCode.equals(currencyCode)); return new Fiat(currencyCode, LongMath.checkedSubtract(this.value, value.value)); } public Fiat multiply(final long factor) { return new Fiat(currencyCode, LongMath.checkedMultiply(this.value, factor)); } public Fiat divide(final long divisor) { return new Fiat(currencyCode, this.value / divisor); } public Fiat[] divideAndRemainder(final long divisor) { return new Fiat[] { new Fiat(currencyCode, this.value / divisor), new Fiat(currencyCode, this.value % divisor) }; } public long divide(final Fiat divisor) { checkArgument(divisor.currencyCode.equals(currencyCode)); return this.value / divisor.value; } /** * Returns true if and only if this instance represents a monetary value greater than zero, otherwise false. */ public boolean isPositive() { return signum() == 1; } /** * Returns true if and only if this instance represents a monetary value less than zero, otherwise false. */ public boolean isNegative() { return signum() == -1; } /** * Returns true if and only if this instance represents zero monetary value, otherwise false. */ public boolean isZero() { return signum() == 0; } /** * Returns true if the monetary value represented by this instance is greater than that of the given other Coin, * otherwise false. */ public boolean isGreaterThan(Fiat other) { return compareTo(other) > 0; } /** * Returns true if the monetary value represented by this instance is less than that of the given other Coin, * otherwise false. */ public boolean isLessThan(Fiat other) { return compareTo(other) < 0; } @Override public int signum() { if (this.value == 0) return 0; return this.value < 0 ? -1 : 1; } public Fiat negate() { return new Fiat(currencyCode, -this.value); } /** * Returns the number of satoshis of this monetary value. It's deprecated in favour of accessing {@link #value} * directly. */ public long longValue() { return this.value; } private static final MonetaryFormat FRIENDLY_FORMAT = MonetaryFormat.FIAT.postfixCode(); /** * Returns the value as a 0.12 type string. More digits after the decimal place will be used if necessary, but two * will always be present. */ public String toFriendlyString() { return FRIENDLY_FORMAT.code(0, currencyCode).format(this).toString(); } private static final MonetaryFormat PLAIN_FORMAT = MonetaryFormat.FIAT.minDecimals(0) .repeatOptionalDecimals(1, 4).noCode(); /** * <p> * Returns the value as a plain string denominated in NEOS. The result is unformatted with no trailing zeroes. For * instance, a value of 150000 satoshis gives an output string of "0.0015" NEOS * </p> */ public String toPlainString() { return PLAIN_FORMAT.format(this).toString(); } @Override public String toString() { return Long.toString(value); } @Override public boolean equals(final Object o) { if (o == this) return true; if (o == null || o.getClass() != getClass()) return false; final Fiat other = (Fiat) o; if (this.value != other.value) return false; if (!this.currencyCode.equals(other.currencyCode)) return false; return true; } @Override public int hashCode() { return (int) this.value + 37 * this.currencyCode.hashCode(); } @Override public int compareTo(final Fiat other) { if (!this.currencyCode.equals(other.currencyCode)) return this.currencyCode.compareTo(other.currencyCode); if (this.value != other.value) return this.value > other.value ? 1 : -1; return 0; } }