Thread: need help with 2D array

System.out.println(rollnumber.split("IAD")[1])

Doesn't seem right to me, with the [] around the 1.

If anything, it'd be split("IAD", 1);

Actually, it could be

System.out.println(Arrays.toString(rollnumber.spli t("IAD", 1)));

Crossposted: need help with 2D array - Java Forums

Originally Posted by javapenguin

Doesn't seem right to me, with the [] around the 1.

If anything, it'd be split("IAD", 1);

Actually, it could be

System.out.println(Arrays.toString(rollnumber.spli t("IAD", 1)));

But what happened when you tried it?

Because you're wrong. The syntax is perfectly legal. Yet again, you're offering advice that is absolutely not true. I'm a little more forward about calling you out on it than the other members, but it's really misleading to the other novice programmers that we're trying to help.

Please, please, please, at least start trying these things yourself before you post about them. Throwing together a sample program to test this syntax took me less than 30 seconds.

Originally Posted by javapenguin

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1

Okay, but that's not a syntax error, as you erroneously indicated. That's not a compile-time error, it's a runtime error. It's not a problem with the syntax itself ("with the [] around the 1", as you said), it's a problem with the logic. Do you see how that can be confusing?

If you think there's a problem with the syntax, throw together a simple program to prove it, without worrying about any other logic errors. Here's one that proves that the syntax is fine:

class Main  {
    public static void main(String[] ar){
    	System.out.println("1 2 3 4 5".split(" ")[1]);
    }
}

It should be

System.out.println(rollnumber.split("IAD")[0]);

I see now that the 0 would be index 0 of the array the split method is creating.

Originally Posted by javapenguin

It should be

System.out.println(rollnumber.split("IAD")[0]);

I see now that the 0 would be index 0 of the array the split method is creating.

Sigh. No. Again, wrong. Again, misleading advice.

What did you get when you ran that line? Or a similar line? Here, I'll even give you this example program again, since you don't seem to know how to make one yourself:

class Main  {
    public static void main(String[] ar){
    	System.out.println("IAD123".split("IAD")[0]);
    }
}

In my opinion, it seems like overkill for the OP to use anything except substring here. And no, that doesn't mean you should attempt to throw together a full solution for him.

And that's just the first issue. The OP's main problem of storing things into a 2D array should be treated as completely separate.

Originally Posted by javapenguin

The problem is that sometimes I, like others, don't know we're doing it wrong.

Which is why you should be extra careful when posting advice. I'm no expert, but I've been programming Java for 8 years or so, and I still throw together sample programs all the time to make sure my assumptions are true. If you're going to post advice, you have to test your assumptions, especially since it's apparent that your level of understanding is oftentimes lower than that of the original posters.

When I originally saw your post about the syntax being incorrect, I thought you were wrong, but before I posted anything, I tested that assumption by writing that basic program. It took me less than 30 seconds. Why can't you do the same thing before you post your assumptions, especially given your track record of posting incorrect information?

Originally Posted by javapenguin

I didn't realize I could get kicked out for giving advice, especially advice that seems to make sense to me at the time.

I'm not a mod, so I don't have any say in what forms of punishment you can/should receive, but I have personally showed you the problems with posting incorrect information, and I've suggested you try code yourself before offering invalid assumptions about it, yet you continue to ignore that advice and continue to mislead other users. That's bad for the users who follow your bad advice, it's bad for the forums as they become known for this kind of response, it's bad for you because you don't learn by testing your assumptions, and it's bad for anybody else who stumbles upon your faulty advice later. Not to mention the distraction caused by the repeated need to tell you about this, again and again.

You also have a strange propensity towards offering full solutions, despite the fact that they are often wrong and are never helpful (I've shown you many times why spoonfeeding is not helping). Posting code examples can be a great way to help, but you take away the process of using examples to work out a solution, which is one of the most important skills an amateur must learn. I told the OP about the substring function (to be fair, I only mentioned it to point out how the previous discussions were overkill, as I don't really love helping crossposters), and I even told you that it wasn't an invitation to take that and try to come up with the code yourself because I know how you are, but still you post the exact code in your next reply. Why? Who are you trying to impress? If you want to learn by trying to solve the problems, that's fine, but why take that process away from the other users? You aren't helping.

For these reasons, and because of your refusal to learn from your mistakes, if it were up to me, you'd be banned already. I'm not telling you to stop helping- in fact, I'm trying to help you be more helpful. But you continue to refuse to listen to any of this advice, and you continue to give out incorrect information, which would have been very easily corrected with a simple test program.

Originally Posted by javapenguin

I compiled the original code the OP gave, found that it gave an error, which I posted, pointed out that if the value were changed to 0, it wouldn't show that error, and got read the riot act.

That's because none of that is helpful. Sure changing it to 0 gets rid of that runtime error, but what does that have to do with syntax? And further, changing it to 0 does NOT fix the OP's actual problem. Do you understand why? Did you even bother running the test program I wrote for you?

Originally Posted by javapenguin

Also, I didn't notice the OPs question. I kinda saw the code and thought that's what I should focus on. My bad.

So let me get this straight- you don't even read the posts before trying to offer your shoddy advice? That explains a lot.