Here you can find the source of assertNull(String string, Object obj)
public static void assertNull(String string, Object obj)
//package com.java2s; //License from project: Apache License public class Main { public static void assertNull(String string, Object obj) { assertTrue(string, obj == null); }/*from w ww .j a v a 2s .c o m*/ public static void assertTrue(String string, boolean b) { if (!b) throw new IllegalStateException(string); } }