Are these references really the same?
Suppose we have the following code snippet:
Cat cat = new Cat(); // The Cat class extends Animal ArrayList<Animal> animalList = new ArrayList<>(); animalList.add(cat);
catis a reference of type
Catthat points to an object of type
animalList.get(0)is a reference of type
Animalthat points to the same object as the cat reference.
cat == animalList.get(0)will evaluate to
truesince they are both pointing to the same object.
However, one reference is of type
Cat and the other of type
Animal(position 0 in list), so am I wrong in saying that the references are not entirely equal, even though they point to the same memory location? Am I looking into the terminology too much?
This existing answer uses a nice analogy around houses, which describes references as "addresses", that allow you to find "houses" (those represent the instantiated objects).
If you extend that thinking, you could say that it's possible to print addresses on different cards. So these cards look different, but the address printed on them is always the same.
So yes, the compiler has a certain understanding of the references (or to be precise: **variables) being "different" (you can't invoke the Cat methods on an
Animal reference). But at runtime, that part is completely gone. Then we are only comparing the "address" printed on the "cards".
5 Reference Mistakes That Can Cost You The Job, To ensure your references present you in the best light, avoid these common think you were a great employee, your past manager may not feel the same way. Also note that print and electronic references are largely the same. For example, to cite both print books and ebooks, use the books and reference works category and then choose the appropriate type of work (i.e., book) and follow the relevant example (e.g., whole authored book ).
am I wrong in saying that the references are not entirely equal, even though they point to the same memory location?
Yes, you're wrong. A reference is effectively just a memory location.
It seems like you're considering the type of the variable to be part of the reference and it isn't.
Do Employers Really Check Work History and References?, This varies depending on the employer, but at some point, if you are a serious candidate, they will most likely check your job references and perform a background You’ve aced your interviews and the job is almost yours, but the fate of your employment could rest in the hands of others: your professional references. Just when you thought the hiring process couldn’t get more nerve-wracking, it does. You’re left wondering: “What will my reference say about me? What will the recruiter ask about?
It's a magic of Polymorphism (dynamic polymorphism).
The actual object is determined at runtime and not compile time.
So actually cat and animal is the same (cat) and reference to the same memory.
Please view more detail in this article
It explained very well.
Re: How to get a job without any references, I'm in the same situation. I was raised in foster homes and I never really connected with anyone socially. Three of the places that worked, are now Unfortunately, “references are often an afterthought for job seekers,” says Andrea Kay, a career consultant based in Cincinnati. To ensure your references present you in the best light, avoid these common mistakes. Professional reference list mistakes to avoid. Not asking a person for permission to list them as a reference
so am I wrong in saying that the references are not entirely equal, even though they point to the same memory location?
Yes. They are the same piece of memory/instance, so nothing changes in your memory (it remains at the same memory location). There is no difference or any loss of information when you treat a
Cat as an
Animal in your code. However, you will only be able to get the
Animal's properties since you choose to treat the object as an
Animal. If you want to get the
Cat's specifics as well, you can just cast the object. This entire process happens only in the preprocessing of the code compilation.
More about casting and this way of working can be seen here: How does Java Object casting work behind the scene?
Frege: Philosophy of Language, Then it becomes absurd to think of reference as attaching only to the singular terms of We are not accustomed to thinking of these latter expressions in the same It is true that we derive from these very little help by enquiring whether Frege These terms mean the same thing. Each is an alphabetical list of works cited, or works to which you have made reference. Works Cited is generally used when citing sources using MLA (Modern Language Association) style, while the title References is used when citing sources using APA (American Psychological Association) style.
It's Time to Scrap Reference Checking – Here is Why, The person checking the references is usually the recruiter – NOT the hiring manager who really should be having these conversations (really Most HR Departments Check References During Employment Screening: According to a SHRM survey, 87% of employers do reference checks as part of the hiring process. Expect to Have Your References Checked: Potential employers will likely learn about your employment history, eligibility for rehire, and job performance.
Do references really matter?, The importance of references seems to be a hot topic these days. Employers want to make sure they are hiring the right person for the job; but For references that are in press or that have no date (signified by n.d., which stands for “no date”), use the following forms for the date: (in press-a), (in press-b), (n.d.-a), and (n.d.-b), and so forth. A Solution for Not-Quite Twins. However, be careful that your references are true identical twins.
The Dreams That Stuff Is Made Of: The Most Astounding Papers of , The Most Astounding Papers of Quantum Physics--and How They Shook the or what is the same thing, when the latter's Fourier expansion in terms of the time for these references but also for very valuable oral instruction in these not very Formatting a Reference List. Your reference list should appear at the end of your paper. It provides the information necessary for a reader to locate and retrieve any source you cite in the body of the paper. Each source you cite in the paper must appear in your reference list; likewise, each entry in the reference list must be cited in your text.