EqualsUtil.java

/**
 *    Copyright 2006-2016 the original author or authors.
 *
 *    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.mybatis.generator.internal.util;

/**
 * This class is from javapractices.com:
 * 
 * http://www.javapractices.com/Topic17.cjp
 * 
 * Collected methods which allow easy implementation of <code>equals</code>.
 * 
 * Example use case in a class called Car:
 * 
 * <pre>
 * public boolean equals(Object that) {
 *     if (this == that)
 *         return true;
 *     if (!(that instanceof Car))
 *         return false;
 *     Car thatCar = (Car) that;
 *     return EqualsUtil.areEqual(this.fName, that.fName)
 *             && EqualsUtil.areEqual(this.fNumDoors, that.fNumDoors)
 *             && EqualsUtil.areEqual(this.fGasMileage, that.fGasMileage)
 *             && EqualsUtil.areEqual(this.fColor, that.fColor)
 *             && Arrays.equals(this.fMaintenanceChecks, that.fMaintenanceChecks); //array!
 * }
 * </pre>
 * 
 * <em>Arrays are not handled by this class</em>. This is because the
 * <code>Arrays.equals</code> methods should be used for array fields.
 */
public final class EqualsUtil {

    /**
     * Are equal.
     *
     * @param aThis
     *            the a this
     * @param aThat
     *            the a that
     * @return true, if successful
     */
    static public boolean areEqual(boolean aThis, boolean aThat) {
        return aThis == aThat;
    }

    /**
     * Are equal.
     *
     * @param aThis
     *            the a this
     * @param aThat
     *            the a that
     * @return true, if successful
     */
    static public boolean areEqual(char aThis, char aThat) {
        return aThis == aThat;
    }

    /**
     * Are equal.
     *
     * @param aThis
     *            the a this
     * @param aThat
     *            the a that
     * @return true, if successful
     */
    static public boolean areEqual(long aThis, long aThat) {
        /*
         * Implementation Note Note that byte, short, and int are handled by
         * this method, through implicit conversion.
         */
        return aThis == aThat;
    }

    /**
     * Are equal.
     *
     * @param aThis
     *            the a this
     * @param aThat
     *            the a that
     * @return true, if successful
     */
    static public boolean areEqual(float aThis, float aThat) {
        return Float.floatToIntBits(aThis) == Float.floatToIntBits(aThat);
    }

    /**
     * Are equal.
     *
     * @param aThis
     *            the a this
     * @param aThat
     *            the a that
     * @return true, if successful
     */
    static public boolean areEqual(double aThis, double aThat) {
        return Double.doubleToLongBits(aThis) == Double.doubleToLongBits(aThat);
    }

    /**
     * Possibly-null object field.
     * 
     * Includes type-safe enumerations and collections, but does not include arrays. See class comment.
     *
     * @param aThis
     *            the a this
     * @param aThat
     *            the a that
     * @return true, if successful
     */
    static public boolean areEqual(Object aThis, Object aThat) {
        return aThis == null ? aThat == null : aThis.equals(aThat);
    }
}