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This is a set of utilities and classes that I have found useful over the years. In my career spanning over a decade, I have time and again written the same code or some part of the code over and over again. I never found the time to collate the details in a reusable library. This project will be a collection of such files. The work that I have been doing is more than 5 years old, however the project has been conceived in 2011.

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/*******************************************************************************
 * Copyright 2011 @ Kapil Viren Ahuja
 * 
 * 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 com.kapil.framework.lang;


/**
 * Assertion utility class that assists in validating arguments. Useful for identifying programmer errors early and
 * clearly at runtime.
 * 
 * 
 * This class is similar to TestNG's assertion library. If an argument value is deemed invalid, an
 * {@link AssertionError} is thrown.
 * 
 */
public abstract class Assert
{

    /**
     * Assert a boolean expression, throwing AssertionError if the test result is
     * false.
     * 
     * 
     * Assert.isTrue(count > 0, "The value should be greater than zero");
     * 
     * 
     * @param expression a boolean expression
     * @param message the exception message to use if the assertion fails
     * @throws AssertionError if expression is false
     */
    public static void isTrue(boolean expression, String message)
    {
        if (!expression)
        {
            throw new AssertionError(message);
        }
    }


    /**
     * Assert a boolean expression, throwing AssertionError if the test result is
     * false.
     * 
     *      * Assert.isTrue(count > 0);
     * 
     * 
     * @param expression a boolean expression
     * @throws AssertionError if expression is false
     */
    public static void isTrue(boolean expression)
    {
        isTrue(expression, "Assertion failed - this expression must be true");
    }


    /**
     * Assert that an object is null .
     * 
     *      * Assert.isNull(value, "The value must be null");
     * 
     * 
     * @param object the object to check
     * @param message the exception message to use if the assertion fails
     * @throws AssertionError if the object is not null
     */
    public static void isNull(Object object, String message)
    {
        if (object != null)
        {
            throw new AssertionError(message);
        }
    }


    /**
     * Assert that an object is null .
     * 
     *      * Assert.isNull(value);
     * 
     * 
     * @param object the object to check
     * @throws AssertionError if the object is not null
     */
    public static void isNull(Object object)
    {
        isNull(object, "Assertion failed - the object argument must be null");
    }


    /**
     * Assert that an object is not null .
     * 
     *      * Assert.notNull(clazz, "The class must not be null");
     * 
     * 
     * @param object the object to check
     * @param message the exception message to use if the assertion fails
     * @throws AssertionError if the object is null
     */
    public static void notNull(Object object, String message)
    {
        if (object == null)
        {
            throw new AssertionError(message);
        }
    }


    /**
     * Assert that an object is not null .
     * 
     *      * Assert.notNull(clazz);
     * 
     * 
     * @param object the object to check
     * @throws AssertionError if the object is null
     */
    public static void notNull(Object object)
    {
        notNull(object, "Assertion failed - this argument is required; it must not be null");
    }
}