Here you can find the source of assertNotNull(Object object, String message)
public static void assertNotNull(Object object, String message)
//package com.java2s; //License from project: Apache License public class Main { public static void assertNotNull(Object object, String message) { if (object == null) error(message);//from w w w . jav a 2 s .c o m } /** @throws IllegalArgumentException exception */ public static void error(String msg) { throw new IllegalArgumentException(msg); } }