common/src/main/java/org/conscrypt/Preconditions.java

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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.conscrypt;

/**
 * Static convenience methods that help a method or constructor check whether it was invoked
 * correctly (that is, whether its <i>preconditions</i> were met).
 */
final class Preconditions {
    private Preconditions() {}

    /**
     * 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.
     * @return the non-null reference that was validated
     * @throws NullPointerException if {@code reference} is null
     */
    static <T> T checkNotNull(T reference, String errorMessage) {
        if (reference == null) {
            throw new NullPointerException(errorMessage);
        }
        return reference;
    }

    /**
     * Ensures the truth of an expression involving one or more parameters to the calling method.
     */
    static void checkArgument(boolean condition, String errorMessage) {
        if (!condition) {
            throw new IllegalArgumentException(errorMessage);
        }
    }

    /**
     * Ensures the truth of an expression involving one or more parameters to the calling method.
     */
    static void checkArgument(boolean condition, String errorMessageTemplate, Object arg) {
        if (!condition) {
            throw new IllegalArgumentException(String.format(errorMessageTemplate, arg));
        }
    }
}