Is it bad practice to make a setter return “this”?

Question

Is it a good or bad idea to make setters in java return \"this\"?

public Employee setName(String name){
   this.name = name;
   return this;
}

Answer 1

I agree with all posters claiming this breaks the JavaBeans spec. There are reasons to preserve that, but I also feel that the use of this Builder Pattern (that was alluded to) has its place; as long as it is not used everywhere, it should be acceptable. "It's Place", to me, is where the end point is a call to a "build()" method.

There are other ways of setting all these things of course, but the advantage here is that it avoids 1) many-parameter public constructors and 2) partially-specified objects. Here, you have the builder collect what's needed and then call its "build()" at the end, which can then ensure that a partially-specified object is not constructed, since that operation can be given less-than-public visibility. The alternative would be "parameter objects", but that IMHO just pushes the problem back one level.

I dislike many-parameter constructors because they make it more likely that a lot of same-type arguments are passed in, which can make it easier to pass the wrong arguments to parameters. I dislike using lots of setters because the object could be used before it is fully configured. Further, the notion of having default values based on previous choices is better served with a "build()" method.

In short, I think it is a good practice, if used properly.