Assert.java

/*******************************************************************************
 * Copyright (c) 2011, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation
 *
 ******************************************************************************/
package org.eclipse.persistence.jpa.jpql;

/**
 * An utility class that provides various checks and when the condition fails, then an {@link
 * AssertException} is thrown.
 *
 * @version 2.4
 * @since 2.4
 * @author Pascal Filion
 */
public final class Assert {

    /**
     * Prevents instantiation.
     */
    private Assert() {
        super();
    }

    /**
     * Throws an {@link AssertException} immediately.
     *
     * @param message The message to display
     */
    public static void fail(String message) {
        throw new AssertException(message);
    }

    /**
     * Determines whether the given two objects are equal (identity). If the two objects are not
     * identical, then an {@link AssertException} is thrown
     *
     * @param object1 The first object used to be compared to the second object
     * @param object2 The second object used to be compared to the first object
     * @param message The expression's message that will describe the reason why the check failed
     */
    public static void isEqual(Object object1, Object object2, String message) {
        if (object1 != object2) {
            fail(message);
        }
    }

    /**
     * Determines whether the given condition if <code>false</code> or <code>true</code> and if it is
     * <code>true</code> then an {@link AssertException} is thrown.
     *
     * @param condition The condition to verify it is <code>false</code>
     * @param message The expression's message that will describe the reason why the check failed
     */
    public static void isFalse(boolean condition, String message) {
        if (condition) {
            fail(message);
        }
    }

    /**
     * Determines whether the given object is not <code>null</code>. If the object is <code>null</code>,
     * then an {@link NullPointerException} is thrown
     *
     * @param object The value to check to not be <code>null</code>
     * @param message The expression's message that will describe the reason why the check failed
     */
    public static void isNotNull(Object object, String message) {
        if (object == null) {
            throw new NullPointerException(message);
        }
    }

    /**
     * Determines whether the given object is <code>null</code>. If the object is not <code>null</code>,
     * then an {@link AssertException} is thrown
     *
     * @param object The value to check to be <code>null</code>
     * @param message The expression's message that will describe the reason why the check failed
     */
    public static void isNull(Object object, String message) {
        if (object != null) {
            fail(message);
        }
    }

    /**
     * Determines whether the given condition if <code>true</code> or <code>false</code> and if it is
     * <code>false</code> then an {@link AssertException} is thrown.
     *
     * @param condition The condition to verify it is <code>true</code>
     * @param message The expression's message that will describe the reason why the check failed
     */
    public static void isTrue(boolean condition, String message) {
        if (!condition) {
            fail(message);
        }
    }

    /**
     * Determines whether the given object is one of the given choices using identity check.
     *
     * @param object The object to find in the list of choices
     * @param message The expression's message that will describe the reason why the check failed
     * @param choices The list of valid choices
     */
    public static void isValid(Object object, String message, Object... choices) {
        for (Object choice : choices) {
            if (object == choice) {
                return;
            }
        }
        fail(message);
    }

    /**
     * The exception thrown when the condition is not met.
     */
    public static class AssertException extends RuntimeException {

        /**
         * Creates a new <code>AssertException</code>.
         *
         * @param message The message describing the reason why this exception is thrown
         */
        public AssertException(String message) {
            super(message);
        }
    }
}