title: can 'this' pointer be null in c++ class?
body: <p>There is a c++ code shown below:</p>
  
  <pre><code>class Metadata : public MetaspaceObj {
      void print_value_on_maybe_null(outputStream* st) const {
      if (this == NULL)
        st-&gt;print("NULL");
      else
        print_value_on(tty);
      }
  }
  </code></pre>
  
  <p>I just wonder how could 'this' be NULL in a C++ object.Could be there a possibility?</p>
  
  <p>The code above is excerpted from jdk8/openjdk/hotspot/src/share/vm/oops/metadata.hpp.</p>