ValidationUtil.java

/*
 *   The MIT License (MIT)
 *
 *   Copyright (c) 2016 Cleveroad
 *
 *   Permission is hereby granted, free of charge, to any person obtaining a copy
 *   of this software and associated documentation files (the "Software"), to deal
 *   in the Software without restriction, including without limitation the rights
 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *   copies of the Software, and to permit persons to whom the Software is
 *   furnished to do so, subject to the following conditions:
 *
 *   The above copyright notice and this permission notice shall be included in all
 *   copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 *   SOFTWARE.
 */
package com.cleveroad.slidingtutorial;

import android.support.annotation.Nullable;

final class ValidationUtil {

    private ValidationUtil() {
    }

    /**
     * Ensures that an object reference passed as a parameter to the calling method is not null.
     *
     * @param reference an object reference
     * @return the non-null reference that was validated
     * @throws NullPointerException if {@code reference} is null
     */
    static <T> T checkNotNull(T reference) {
        if (reference == null) {
            throw new NullPointerException();
        }
        return reference;
    }

    /**
     * Ensures that an object reference passed as a parameter to the calling method is not null.
     *
     * @param reference    an object reference
     * @param errorMessage the exception message to use if the check fails; will be converted to a
     *                     string using {@link String#valueOf(Object)}
     * @return the non-null reference that was validated
     * @throws NullPointerException if {@code reference} is null
     */
    static <T> T checkNotNull(T reference, @Nullable Object errorMessage) {
        if (reference == null) {
            throw new NullPointerException(String.valueOf(errorMessage));
        }
        return reference;
    }

    /**
     * Checks setPagesCount value to be greater that 0
     *
     * @param pagesCount count of pages
     * @return pages count
     * @throws IllegalArgumentException when setPagesColors array has different from setPagesCount value size
     */
    static int checkPagesCount(int pagesCount) {
        if (pagesCount < 0) {
            throw new IllegalArgumentException("Pages count can't be less than 0.");
        }
        return pagesCount;
    }

    /**
     * Checks position value to be greater that 0
     *
     * @param position page position
     * @return position value
     * @throws IllegalArgumentException when position less than 0
     */
    static int checkPosition(int position) {
        if (position < 0) {
            throw new IllegalArgumentException("Position can't be less than 0.");
        }
        return position;
    }
}