Can constructor return a null object?

While looking through some old code I came across this gem:

MyObject o = new MyObject("parameter");
if (o == null) o = new MyObject("fallback parameter");

The second line is marked in Eclipse as dead code, and I understand why. No exception seems to be explicitly thrown, and it isn't possible for the MyObject constructor to throw any kind of exception (such as NullPointerExceptions).

My question is why there is a null check? Was it previously possible in an old version of Java for a constructor to return null? Or is this simply useless and dead code?

The code is dead in any version of Java. It's not possible for a constructor to return null, and even if an exception would be thrown from the constructor, the next line won't be called.

No, it has never been possible. Maybe a previous version of the code used some factory method which could return null:

MyObject o = createMyObject("parameter");
if (o == null) o = createMyObject("fallback parameter");

From section 15.9.4 of the JLS:

The value of a class instance creation expression is a reference to the newly created object of the specified class. Every time the expression is evaluated, a fresh object is created.

So no, it can never return null.

My guess is that it was written by a C programmer who is used to testing the return value of malloc() for NULL, malloc() can return NULL if your system runs out of memory.

The code doesn't make sense in Java since Java will throw an OutOfMemoryError` if it runs out of memory.

The answer is simple: person who wrote the code was a paranoid c++ programmer. In C++ you may overload operator new and use it as a simple memory allocator (aka malloc).