Thread: Command For Rolling Random Number

I'm learning Java and giving myself small tasks just in my spare time, one thing I've done is having a small command line interface, one of the commands is "roll" followed by a number from 1-9. For example roll 3 = random number with 3 digits.
How do I stop my command line interface from crashing when you input something like "roll L" or other strings that cannot be converted into an integer?
My way around this is terrible, but it'll have to do, it looks similar to the code below.

if(theCommand.equalsIgnoreCase("roll 1") || theCommand.equalsIgnoreCase("roll 2") || theCommand.equalsIgnoreCase("roll 3") || theCommand.equalsIgnoreCase("roll 4") || theCommand.equalsIgnoreCase("roll 5") || theCommand.equalsIgnoreCase("roll 6") || theCommand.equalsIgnoreCase("roll 7") || theCommand.equalsIgnoreCase("roll 8") || theCommand.equalsIgnoreCase("roll 9")){
//Coding goes here
}

As apposed to how I had it converting the string into an integer

(int x = Integer.parseInt(testCommand.substring(5))

After this was executed there'd be a random number generated, that number would then be multiplied by (10 to the power of x).

I just need to limit the input to just "roll 1-9"

Thank you very much,

If you're confused, just ask, because I am too..

Sounds like you may want to wrap the parse in a try catch clause, and be prepared to catch a number format exception.

Originally Posted by sunde

Sounds like you may want to wrap the parse in a try catch clause, and be prepared to catch a number format exception.

That's what I want! But I don't know how to make that..

try{
  //try something
} catch(/*some exception*/){
  //do something as a result of catching the exception
}

read up on exceptions if necessary.

Originally Posted by sunde

try{
  //try something
} catch(/*some exception*/){
  //do something as a result of catching the exception
}

read up on exceptions if necessary.

I know the try and catch, I just don't know how to make the exception or how to set it out.. That's my problem.

When you try and parse an integer that contains something other than 0-9, what happens? Is an exception thrown? If so, which?

Try catching that exception in the catch and do whatever you want in the handling(exit the program, prompt for correct input, etc.)

I'm glad to have helped.