Does @NotNull work at runtime
<p>I have recently decided to start using null checksum annotations (<code>@NotNull</code>), I use <a href="https://www.jetbrains.com/help/idea/2016.2/nullable-and-notnull-annotations.html" rel="nofollow">Intellij Idea's annotations library</a> to get access these. I am trying to figure out whether or not these annotations will work at runtime to check if values are null and if so how does it handle these errors (e.g. does it throw a <code>NullPointerException</code>, does it just return a default value (e.g. null, 0, false)). Also if these annotations do not work is there a different set that may be more standardized annotations that will work at runtime (e.g. <code>javax</code>)? If these do not work should I stop using them and return to a standard null checksum (<code>if(x == null)</code>) or should use both the annotations as well as standard null checksums? And while I am here are annotations like @Nullable a good idea?</p>