Math.Random()

[Tripmaker]

Hi! I'm new at Java and enjoying what I've learned to date. I'm busy designing a GUI (for customers of a Video store). My question is: I want to use Math.random() to generate a unique customer no. The problem is I'm using a TextField and the error that keeps coming up is that I'm unable to use int in a String field. How can I get passed this?

Thank you
Petra

[r035198x]

Hi! I'm new at Java and enjoying what I've learned to date. I'm busy designing a GUI (for customers of a Video store). My question is: I want to use Math.random() to generate a unique customer no. The problem is I'm using a TextField and the error that keeps coming up is that I'm unable to use int in a String field. How can I get passed this?

Thank you
Petra

Hi and welcome to TSDN. I've moved your question to the Java forum.
If you want an int value to be displayed as a String you can use ""+intValue (empty String concatenated with the int value).

Have you gone through a Java tutorial yet?

[JosAH]

On top of all that Math.random() generates pseudo random numbers in the interval
[0,1). Given the fact that a double has about 15 significant digits there is a slight
chance that a random number will be generated that has been generated before.

kind regards,

Jos (<-- nitpicker)

[Tripmaker]

Hi and welcome to TSDN. I've moved your question to the Java forum.
If you want an int value to be displayed as a String you can use ""+intValue (empty String concatenated with the int value).

Have you gone through a Java tutorial yet?

Thanks for your welcome and help. I've just completed a 10 month intense Java course at a private college and am working on a project that needs to be handed in in 2 weeks time. So I'm very new at all of this. I've tried surging the tutorials but haven't anything to help me.

Regards
Petra

[r035198x]

Thanks for your welcome and help. I've just completed a 10 month intense Java course at a private college and am working on a project that needs to be handed in in 2 weeks time. So I'm very new at all of this. I've tried surging the tutorials but haven't anything to help me.

Regards
Petra

You may also find the java.util.Rando m class to be of interest.

[blazedaces]

Hi! I'm new at Java and enjoying what I've learned to date. I'm busy designing a GUI (for customers of a Video store). My question is: I want to use Math.random() to generate a unique customer no. The problem is I'm using a TextField and the error that keeps coming up is that I'm unable to use int in a String field. How can I get passed this?

Thank you
Petra

Try isolating your problem. For example, questions that pop up in my head:

Doesn't math.random() produce a double between 0 and 1? Are you casting it to int? What are you doing along the way?

Mostly, does the problem have anything to do with random()? Or is the problem simply that you can't put an int on a text field?

Ways you can isolate your problem:

-debug your code (i.e. print out values along the way until you discover EXACTLY where the problem lies, like if you're producing the correct number and it's simply not appearing or if the number is wrong as well, etc.)

-test your methods out separately in a test-program

Knowing what problem you actually have is the first step to finding a proper solution.

Good luck and I hope this was helpful,

-blazed

[JosAH]

If I were the OP I'd simply marshal sequential numbers to the customers: 1, 2, 3
etc. etc. The counter needs to be persistent but that's all. Use an eight byte long
for the counter so you can hand out a unique number to every living creature in
the solar system if you want; and that includes red cabbage, which I hate. ;-)

kind regards,

Jos

[Tripmaker]

Try isolating your problem. For example, questions that pop up in my head:

Doesn't math.random() produce a double between 0 and 1? Are you casting it to int? What are you doing along the way?

Mostly, does the problem have anything to do with random()? Or is the problem simply that you can't put an int on a text field?

Ways you can isolate your problem:

-debug your code (i.e. print out values along the way until you discover EXACTLY where the problem lies, like if you're producing the correct number and it's simply not appearing or if the number is wrong as well, etc.)

-test your methods out separately in a test-program

Knowing what problem you actually have is the first step to finding a proper solution.

Good luck and I hope this was helpful,

-blazed

I can not put an int on a text field.

this is part of my code:

int randNo = 0;
randNo = (int)((Math.ran dom()*700)+1);
custIdText.setT ext(randNo);

Petra

[JosAH]

I can not put an int on a text field.

this is part of my code:

int randNo = 0;
randNo = (int)((Math.ran dom()*700)+1);
custIdText.setT ext(randNo);

Petra

That problem was solved long ago in your first reply (see above) given by r035198x.

kind regards,

Jos

[Tripmaker]

That problem was solved long ago in your first reply (see above) given by r035198x.

kind regards,

Jos

Hi Jos

Sorry, my fault. Didn't read the answer correctly. Too many late nights I guess.

Thanks for all you help

Petra

[RedSon]

I'm still worried about your design decision to use random numbers as unique customer numbers. I think its a poor decision and will likely cause errors a long time in the future probably long after you have moved on. If you don't want to use sequential numbering why not use the current system time to create a customer ID. Then in your documentation you can state that customer IDs are created by looking at the system time so be sure that your computer's time is always correct.

[blazedaces]

I'm still worried about your design decision to use random numbers as unique customer numbers. I think its a poor decision and will likely cause errors a long time in the future probably long after you have moved on. If you don't want to use sequential numbering why not use the current system time to create a customer ID. Then in your documentation you can state that customer IDs are created by looking at the system time so be sure that your computer's time is always correct.

Hey may not want it to be sequential or based on time so a customer can't "fake" a customer ID.

I think he should store somewhere the customer ID's already used. That way, even using random numbers he can always check if it's used already and if so, create a new random number. I'm not an expert, so there might be obvious reasons why this is also bad, but the logic makes sense in my head...

-blazed

[JosAH]

Hey may not want it to be sequential or based on time so a customer can't "fake" a customer ID.

I think he should store somewhere the customer ID's already used. That way, even using random numbers he can always check if it's used already and if so, create a new random number. I'm not an expert, so there might be obvious reasons why this is also bad, but the logic makes sense in my head...

-blazed

If you generate numbers in sequence: 1, 2, 3 ... n you can also track that the
numbers in the interval [1,n] are already used and in a much cheaper way too.

kind regards,

Jos

[blazedaces]

If you generate numbers in sequence: 1, 2, 3 ... n you can also track that the
numbers in the interval [1,n] are already used and in a much cheaper way too.

kind regards,

Jos

Yes, but what if we treat the customer number sort of like the number on an install disc? If the computer asks for your customer ID and you input 1, you'll be fine no matter what... (I realize there could be other questions to cross-examine and make sure, but still).

I mean, even then cd key generators are written to get around this, but you have to admit it's a bit more secure...

Cheaper isn't necessarily better. Still, I have no idea what the goal of this program is so I'm just throwing things in the air here...

-blazed

[r035198x]

I'm still worried about your design decision to use random numbers as unique customer numbers. I think its a poor decision and will likely cause errors a long time in the future probably long after you have moved on. If you don't want to use sequential numbering why not use the current system time to create a customer ID. Then in your documentation you can state that customer IDs are created by looking at the system time so be sure that your computer's time is always correct.

Yep, this should really be done database side if the OP is using a database.