因为大部分时间一个人是不是在调试模式下运行，而一些优化code在Android的断言将无法正常工作。因此，正确的解决方法是手动抛出一个异常，用code是这样的：

Assert won't work in Android because most of the time a person isn't running in debug mode, but rather some optimized code. Thus, the proper solution is to manually throw an exception, with code like this:

if (obj==null) throw new AssertionError("Object cannot be null");