MutableDouble.java Source code

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/*
 * 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.
 */

/**
 * A mutable <code>double</code> wrapper.
 * 
 * @see Double
 * @since 2.1
 * @version $Id: MutableDouble.java 618693 2008-02-05 16:33:29Z sebb $
 */
public class MutableDouble extends Number implements Comparable, Mutable {

    /**
     * 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
     *          a value.
     */
    public MutableDouble(double value) {
        super();
        this.value = value;
    }

    /**
     * Constructs a new MutableDouble with the specified value.
     * 
     * @param value
     *          a value.
     * @throws NullPointerException
     *           if the object is null
     */
    public MutableDouble(Number value) {
        super();
        this.value = value.doubleValue();
    }

    // -----------------------------------------------------------------------
    /**
     * Gets the value as a Double instance.
     * 
     * @return the value as a Double
     */
    public Object getValue() {
        return new Double(this.value);
    }

    /**
     * Sets the value.
     * 
     * @param value
     *          the value to set
     */
    public void setValue(double value) {
        this.value = value;
    }

    /**
     * Sets the value from any Number instance.
     * 
     * @param value
     *          the value to set
     * @throws NullPointerException
     *           if the object is null
     * @throws ClassCastException
     *           if the type is not a {@link Number}
     */
    public void setValue(Object value) {
        setValue(((Number) value).doubleValue());
    }

    // -----------------------------------------------------------------------
    // shortValue and bytValue rely on Number implementation
    /**
     * Returns the value of this MutableDouble as a int.
     * 
     * @return the numeric value represented by this object after conversion to
     *         type int.
     */
    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.
     */
    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.
     */
    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.
     */
    public double doubleValue() {
        return value;
    }

    /**
     * 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);
    }

    // -----------------------------------------------------------------------
    /**
     * Gets this mutable as an instance of Double.
     * 
     * @return a Double instance containing the value from this mutable
     */
    public Double toDouble() {
        return new Double(doubleValue());
    }

    // -----------------------------------------------------------------------
    /**
     * 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.
     * 
     * @param operand
     *          the value to add
     * 
     * @since Commons Lang 2.2
     */
    public void add(double operand) {
        this.value += operand;
    }

    /**
     * Adds a value.
     * 
     * @param operand
     *          the value to add
     * @throws NullPointerException
     *           if the object is null
     * 
     * @since Commons Lang 2.2
     */
    public void add(Number operand) {
        this.value += operand.doubleValue();
    }

    /**
     * Subtracts a value.
     * 
     * @param operand
     *          the value to add
     * 
     * @since Commons Lang 2.2
     */
    public void subtract(double operand) {
        this.value -= operand;
    }

    /**
     * Subtracts a value.
     * 
     * @param operand
     *          the value to add
     * @throws NullPointerException
     *           if the object is null
     * 
     * @since Commons Lang 2.2
     */
    public void subtract(Number operand) {
        this.value -= operand.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.
     * @return <code>true</code> if the objects are the same; <code>false</code>
     *         otherwise.
     */
    public boolean equals(Object obj) {
        return (obj instanceof MutableDouble)
                && (Double.doubleToLongBits(((MutableDouble) obj).value) == Double.doubleToLongBits(value));
    }

    /**
     * Returns a suitable hashcode for this mutable.
     * 
     * @return a suitable hashcode
     */
    public int hashCode() {
        long bits = Double.doubleToLongBits(value);
        return (int) (bits ^ (bits >>> 32));
    }

    /**
     * Compares this mutable to another in ascending order.
     * 
     * @param obj
     *          the mutable to compare to
     * @return negative if this is less, zero if equal, positive if greater
     * @throws ClassCastException
     *           if the argument is not a MutableDouble
     */
    public int compareTo(Object obj) {
        MutableDouble other = (MutableDouble) obj;
        double anotherVal = other.value;
        return compare(value, anotherVal);
    }

    /**
     * Returns the String value of this mutable.
     * 
     * @return the mutable value as a string
     */
    public String toString() {
        return String.valueOf(value);
    }

    protected int compare(Object o1, Object o2) {

        if (o1 == null) {
            if (o2 == null) {
                return 0;
            } else {
                return -((Comparable) o2).compareTo(o1);
            }
        } else {
            return ((Comparable) o1).compareTo(o2);
        }

    }
}

/*
 * 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.
 */

/**
 * Provides mutable access to a value.
 * <p>
 * <code>Mutable</code> is used as a generic interface to the implementations
 * in this package.
 * <p>
 * A typical use case would be to enable a primitive or string to be passed to a
 * method and allow that method to effectively change the value of the
 * primitive/string. Another use case is to store a frequently changing
 * primitive in a collection (for example a total in a map) without needing to
 * create new Integer/Long wrapper objects.
 * 
 * @author Matthew Hawthorne
 * @since 2.1
 * @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
 */
interface Mutable {

    /**
     * Gets the value of this mutable.
     * 
     * @return the stored value
     */
    Object getValue();

    /**
     * Sets the value of this mutable.
     * 
     * @param value
     *          the value to store
     * @throws NullPointerException
     *           if the object is null and null is invalid
     * @throws ClassCastException
     *           if the type is invalid
     */
    void setValue(Object value);

}