Premature optimization in Java: when to use “x = foo.getX()” vs simply “foo.getX()”

Question

When I find myself calling the same getter method multiple times, should this be considered a problem? Is it better to [always] assign to a local variable and call only once?

Answer 1

The choice shouldn't really be about performance hit but about code readability.

When you create a variable you can give it the name it deserves in the current context. When you use a same value more than one time it has surely a real meaning, more than a method name (or worse a chain of methods).
And it's really better to read:

String username = user.getName();
SomeMethod1(a, b, username, c);
SomeMethod2(b, username, c);
SomeMethod3(username);

than

SomeMethod1(a, b, user.getName(), c);
SomeMethod2(b, user.getName(), c);
SomeMethod3(user.getName());