Java tutorial
//package com.java2s; 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(final T reference) { if (reference == null) { throw new NullPointerException(); } return reference; } }