Are you familiar with the ternary operator?
x = boolean ? y : z;
Basically, if the boolean is true, then y is assigned to x. Otherwise, z is assigned to x.
The && is a short-circuiting "and" used between two booleans. If the first boolean evaluates to false, then it's impossible for the expression as a whole to be true, so it "short circuits" and the second is not evaluated. In this example, the short-circuiting is used to
test whether paint.getSeq() returns a null value. If it's not null, then it can be dereferenced to call the equals method. But if it is null, then the short circuiting prevents a NullPointerException.
It appears that getSeq() is intended to return a
String reference, because the equals method is checking it against a String literal (an empty String, in this case).
So if getSeq is not null, and not an empty String...