How to check if two objects are equal even if they could be null

Question

Sometimes, I see this:

if (a.equals(b)) do(something);

However, if a is null, a NullPointerException is thrown. Assuming when a==null and b==null or if just a==b that I would want to do(something). What's the simplest way to do this check without getting an exception?

Answer 1

if( a==b || (a!=null && a.equals(b)) )

(The a==b handles the case when both are null.)

Answer 2

Your answer is in your question:

if ((a == null && b == null) || a.equals(b))...

Answer 3

if you want to do something on identity only, then

if (a==b) do(something)

If on on equality, then

if ((a==null && b==null) || a.equals(b)) do(something)

Answer 4

Another way of writing it.

if (a == null ? b == null : a.equals(b))