Java exception.

Energize · 19 Mar 2008 at 10:22

I keep getting the "Exception in thread "main".

Dj_Jestar · 19 Mar 2008 at 10:58

This line, perhaps?

Code:

two = Integer.parseInt(priceperlitrestring.substring(2,3));

If an if statement has more than one line within it's block, you should encapsulate with {}. So for example:

Code:

if (priceperlitrestring.substring(1,2)==".")
one = Integer.parseInt(priceperlitrestring.substring(0,1));
two = Integer.parseInt(priceperlitrestring.substring(2,3));
three = Integer.parseInt(priceperlitrestring.substring(3,4));
four = 0;

should read:

Code:

if (priceperlitrestring.substring(1,2)==".") {
  one = Integer.parseInt(priceperlitrestring.substring(0,1));
  two = Integer.parseInt(priceperlitrestring.substring(2,3));
  three = Integer.parseInt(priceperlitrestring.substring(3,4));
  four = 0;
}

Energize · 19 Mar 2008 at 11:02

Dj_Jestar · 19 Mar 2008 at 14:20

also, you could just convert to floats/doubles.. wouldn't need to split the string.

Energize · 19 Mar 2008 at 14:37

It has to be an integer because it's for a seven segment display.

Dfhaii · 19 Mar 2008 at 17:55

Why are the numbers stored as Strings? If you have them as floats or whatever a dynamic cast to an int should be adequate.

Energize · 19 Mar 2008 at 20:53

Dfhaii said:
Why are the numbers stored as Strings? If you have them as floats or whatever a dynamic cast to an int should be adequate.

I need to select specific digits from them.

Inquisitor · 19 Mar 2008 at 21:45

Energize said:
I need to select specific digits from them.

This can be done in one line without using strings:

Code:

int getDigit(double number, int digit)
{
	return (int)(number * Math.pow(10, digit)) % 10;
}

Energize · 19 Mar 2008 at 22:01

Would that work when the numbers can be anywhere between 0.01 and 999.99?

Inquisitor · 19 Mar 2008 at 22:02

Should do, yeah. You'd pass in 0 as the digit if you wanted the digit immediately to the left of the decimal point, -2 if you wanted the digit two places to the right, 4 if you wanted the digit 4 places to the left, and so on.

Energize · 19 Mar 2008 at 22:09

The problem is I won't know at the time whether there will be 3 or 6 digits in a number, so if say digit 5 is set to -2 and there isn't 2 digits after the decimal point won't that result in an exception?

daven1986 · 19 Mar 2008 at 22:13

just convert the double to a string then do String.charAt(), then check if it is a "." and if it is don't parse in into an Integer. this can be done in a while loop so you won't require those 3 if statements.

Inquisitor · 19 Mar 2008 at 22:18

Energize said:
The problem is I won't know at the time whether there will be 3 or 6 digits in a number, so if say digit 5 is set to -2 and there isn't 2 digits after the decimal point won't that result in an exception?

Nope, it'll just return 0. You could pass -43 or 76 or something similar in and it'd just return 0, as you'd expect it to. There's nothing in there that could actually produce an error, so you're OK.

Dj_Jestar · 19 Mar 2008 at 22:32

Energize said:
It has to be an integer because it's for a seven segment display.

It would make better sense for the sevensegmentdisplay (which for semantics sake should be SevenSegmentDisplay) to accept a float and the conversion occur within the object.