Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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.apache.commons.lang3.mutable; /** * A mutable <code>double</code> wrapper. * <p> * Note that as MutableDouble does not extend Double, it is not treated by String.format as a Double parameter. * * @see Double * @since 2.1 * @version $Id$ */ public class MutableDouble extends Number implements Comparable<MutableDouble>, Mutable<Number> { /** * Required for serialization support. * * @see java.io.Serializable */ private static final long serialVersionUID = 1587163916L; /** The mutable value. */ private double value; /** * Constructs a new MutableDouble with the default value of zero. */ public MutableDouble() { super(); } /** * Constructs a new MutableDouble with the specified value. * * @param value the initial value to store */ public MutableDouble(final double value) { super(); this.value = value; } /** * Constructs a new MutableDouble with the specified value. * * @param value the initial value to store, not null * @throws NullPointerException if the object is null */ public MutableDouble(final Number value) { super(); this.value = value.doubleValue(); } /** * Constructs a new MutableDouble parsing the given string. * * @param value the string to parse, not null * @throws NumberFormatException if the string cannot be parsed into a double * @since 2.5 */ public MutableDouble(final String value) throws NumberFormatException { super(); this.value = Double.parseDouble(value); } //----------------------------------------------------------------------- /** * Gets the value as a Double instance. * * @return the value as a Double, never null */ @Override public Double getValue() { return Double.valueOf(this.value); } /** * Sets the value. * * @param value the value to set */ public void setValue(final double value) { this.value = value; } /** * Sets the value from any Number instance. * * @param value the value to set, not null * @throws NullPointerException if the object is null */ @Override public void setValue(final Number value) { this.value = value.doubleValue(); } //----------------------------------------------------------------------- /** * Checks whether the double value is the special NaN value. * * @return true if NaN */ public boolean isNaN() { return Double.isNaN(value); } /** * Checks whether the double value is infinite. * * @return true if infinite */ public boolean isInfinite() { return Double.isInfinite(value); } //----------------------------------------------------------------------- /** * Increments the value. * * @since Commons Lang 2.2 */ public void increment() { value++; } /** * Decrements the value. * * @since Commons Lang 2.2 */ public void decrement() { value--; } //----------------------------------------------------------------------- /** * Adds a value to the value of this instance. * * @param operand the value to add * @since Commons Lang 2.2 */ public void add(final double operand) { this.value += operand; } /** * Adds a value to the value of this instance. * * @param operand the value to add, not null * @throws NullPointerException if the object is null * @since Commons Lang 2.2 */ public void add(final Number operand) { this.value += operand.doubleValue(); } /** * Subtracts a value from the value of this instance. * * @param operand the value to subtract, not null * @since Commons Lang 2.2 */ public void subtract(final double operand) { this.value -= operand; } /** * Subtracts a value from the value of this instance. * * @param operand the value to subtract, not null * @throws NullPointerException if the object is null * @since Commons Lang 2.2 */ public void subtract(final Number operand) { this.value -= operand.doubleValue(); } //----------------------------------------------------------------------- // shortValue and byteValue rely on Number implementation /** * Returns the value of this MutableDouble as an int. * * @return the numeric value represented by this object after conversion to type int. */ @Override public int intValue() { return (int) value; } /** * Returns the value of this MutableDouble as a long. * * @return the numeric value represented by this object after conversion to type long. */ @Override public long longValue() { return (long) value; } /** * Returns the value of this MutableDouble as a float. * * @return the numeric value represented by this object after conversion to type float. */ @Override public float floatValue() { return (float) value; } /** * Returns the value of this MutableDouble as a double. * * @return the numeric value represented by this object after conversion to type double. */ @Override public double doubleValue() { return value; } //----------------------------------------------------------------------- /** * Gets this mutable as an instance of Double. * * @return a Double instance containing the value from this mutable, never null */ public Double toDouble() { return Double.valueOf(doubleValue()); } //----------------------------------------------------------------------- /** * Compares this object against the specified object. The result is <code>true</code> if and only if the argument * is not <code>null</code> and is a <code>Double</code> object that represents a double that has the identical * bit pattern to the bit pattern of the double represented by this object. For this purpose, two * <code>double</code> values are considered to be the same if and only if the method * {@link Double#doubleToLongBits(double)}returns the same long value when applied to each. * <p> * Note that in most cases, for two instances of class <code>Double</code>,<code>d1</code> and <code>d2</code>, * the value of <code>d1.equals(d2)</code> is <code>true</code> if and only if <blockquote> * * <pre> * d1.doubleValue() == d2.doubleValue() * </pre> * * </blockquote> * <p> * also has the value <code>true</code>. However, there are two exceptions: * <ul> * <li>If <code>d1</code> and <code>d2</code> both represent <code>Double.NaN</code>, then the * <code>equals</code> method returns <code>true</code>, even though <code>Double.NaN==Double.NaN</code> has * the value <code>false</code>. * <li>If <code>d1</code> represents <code>+0.0</code> while <code>d2</code> represents <code>-0.0</code>, * or vice versa, the <code>equal</code> test has the value <code>false</code>, even though * <code>+0.0==-0.0</code> has the value <code>true</code>. This allows hashtables to operate properly. * </ul> * * @param obj the object to compare with, null returns false * @return <code>true</code> if the objects are the same; <code>false</code> otherwise. */ @Override public boolean equals(final Object obj) { return obj instanceof MutableDouble && Double.doubleToLongBits(((MutableDouble) obj).value) == Double.doubleToLongBits(value); } /** * Returns a suitable hash code for this mutable. * * @return a suitable hash code */ @Override public int hashCode() { final long bits = Double.doubleToLongBits(value); return (int) (bits ^ bits >>> 32); } //----------------------------------------------------------------------- /** * Compares this mutable to another in ascending order. * * @param other the other mutable to compare to, not null * @return negative if this is less, zero if equal, positive if greater */ @Override public int compareTo(final MutableDouble other) { return Double.compare(this.value, other.value); } //----------------------------------------------------------------------- /** * Returns the String value of this mutable. * * @return the mutable value as a string */ @Override public String toString() { return String.valueOf(value); } }