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breaks in converting String to Integer

Anissa Pary
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Joined: Jan 02, 2012
Posts: 40




Can anyone please help when I was debugging that it does not go after I wanted to make an Integer from String and it breaks here I cannot see the problem. The test is below





The output is :


22+33 = 55
+33 = 55
number is:


However I wanted it to be number is: 22. Thank you in advance=)


Manoj Kumar Jain
Ranch Hand

Joined: Aug 22, 2008
Posts: 191

How this code is running. I am even not able to compile the code.

and also it gives the java.lang.ClassCastException when I correct and run the code.


Do not wait to strike till the iron is hot; but make it hot by striking....
Manoj Kumar Jain
Ranch Hand

Joined: Aug 22, 2008
Posts: 191

Look how you initialized "numbers" and what values are you placing value in it ??

Can you type cast the result of numbers.get(d) to an String object ?
Anissa Pary
Ranch Hand

Joined: Jan 02, 2012
Posts: 40
Manoj Kumar Jain wrote:Look how you initialized "numbers" and what values are you placing value in it ??

Can you type cast the result of numbers.get(d) to an String object ?

Ok, thanks get it.=) It is because of char=///
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 38412
    
  23
There is a much simpler way to find out whether a char represents a digit or 0.
And don’t write if (...) return true; else return false;Yes, you can do arithmetic with chars, because, contrary to popular belief they are not letters. They are numbers. '0' is stored as (I think) 0x30 = 48decimal. '0' to '9' are a consecutive sequence, so you can use that trick.
There is also a method in the Character class which does the same thing.
J. Kevin Robbins
Bartender

Joined: Dec 16, 2010
Posts: 917
    
  13

Campbell Ritchie wrote:There is a much simpler way to find out whether a char represents a digit or 0.
And don’t write if (...) return true; else return false;Yes, you can do arithmetic with chars, because, contrary to popular belief they are not letters. They are numbers. '0' is stored as (I think) 0x30 = 48decimal. '0' to '9' are a consecutive sequence, so you can use that trick.
There is also a method in the Character class which does the same thing.


That's a neat trick. I couldn't resist playing around with this one, too, but I went another direction.


Now the test becomes:


"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." -- Ted Nelson
Manoj Kumar Jain
Ranch Hand

Joined: Aug 22, 2008
Posts: 191

yes, this trick is good if we need to look for a specific characters instead of consecutive digits/chars. This provide more flexibility to check for the characters appearing in the String/Input.
Anissa Pary
Ranch Hand

Joined: Jan 02, 2012
Posts: 40
Campbell Ritchie wrote:There is a much simpler way to find out whether a char represents a digit or 0.
And don’t write if (...) return true; else return false;Yes, you can do arithmetic with chars, because, contrary to popular belief they are not letters. They are numbers. '0' is stored as (I think) 0x30 = 48decimal. '0' to '9' are a consecutive sequence, so you can use that trick.
There is also a method in the Character class which does the same thing.

Thank you! I did not know that char are not like String)))
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 38412
    
  23
You’re welcome
 
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