assert Vs if(var != null) which way is better or is correct?

Question

In my app i want to close my cursor in finally statement like this :

Cursor cursor = null;
try {
    // some code
} finally {
     cursor.close();
}

My IDE highlight cursor.close(); and tell :

This method can produce nullPointerException

And suggest to way to correct it (im using intelij idea) :
First:

assert cursor != null;
cursor.close();

Second:

if (cursor != null) {
   cursor.close();
} 

I want to know what is difference between them and which way is better approach ?

Answer 1

Java Assertions are only executed if -ea (enable assertions) is passed as argument to the JVM. If assertions are enabled and the boolean expression of an assertion evaluates as false,an AssertionError will be thrown. So assertions are really just useful as debugging feature.

You should definetely use the if syntax.

_{Note that there also is the syntax assert booleanFlag : message; which will pass message as message to the AssertionException if the booleanFlag is false.}