Java tutorial
//package com.java2s; /** * Copyright (C) 2010 Alfredo Morresi * * This file is part of RainbowLibs 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. */ public class Main { /** * 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 */ public 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 */ public static <T> T checkNotNull(T reference, Object errorMessage) { if (reference == null) { throw new NullPointerException(String.valueOf(errorMessage)); } return reference; } }