I know ths is a common question here. I have read the solutions and modified the code then also i am not getting the solution so I have posted my code here.
when I read a value from the text box and parse the value into int from String in servlet, why does it show NumberFormatException?
String ph=request.getParameter("phone");
int phone=Integer.parseInt(ph.trim());// exception is generated here
You can't have any characters or symbols in an int AND the maximum size of an int is 2,147,483,647 which means the phone number 555 555 5555 would be to large to store in an int.
Change the parse to a long and it should fix your problem
A good rule to follow is do not store any number like SSN or Phone numbers's in numerical primitives. You want to leave the numerical primitives for values you plan on doing something math related. Keep them as strings if at all possible.
Because the value you are feeding it is not a valid integer. Make sure it doesn't have strange characters in it.
9835008199 is higher then MAXINT, so that's probaly it.
The docs tell me:
Throws NumberFormatException - if the string does not contain a parsable integer.
On another note: do not store phone numbers as integers. You will get in trouble (you are in fact already). Rule of thumb: if you do not want to do math with a number, it's not an int, but a string.
Use isNumber function to check whether it is a valid number.
Related
I have some HTML page and on this page I will provide the possibility for free text.
For example, it is possible to write in textbox either: 10 or 10 apples.
In a case of writing 10 apples I got NumberFormatException which is correct, but for me will be good to extract only number automatically without javascript writing.
Is it possible to map string from HTML page to the number in my java entity? May be with some annotation or somehow else?
Try:
final String stripped = textbox.getText().replaceAll("[^0-9]", "");
This takes the contents of the text field and strips out any characters that aren't digits. If you need to deal with floating point or negative numbers, it can be done, but becomes more complicated.
I scraped some text from the internet, which I put in an UTF8String. I can use this string normally, but when I select some specific characters (strange character with accents, like in my case รบ), which are not part of the UTF8 standard, I get an error, saying that I used invalid indexes. This only happens when the string contains strange characters; my code works with normal string that do not contain strange characters.
Any way to solve this?
EDIT:
I have a variable word of type SubString{UTF8String}
When I use do method(word), no problems occur. When I do method(word[2:end]) (assuming length of at least 2), I get an error in case the second character is strange (not in UTF8).
Julia does indexing on byte positions instead of character position. It is way more efficient for a variable length encoding like UTF-8, but it makes some operations use some more boilerplate.
The problem is that some codepoints is encoded as multiple bytes and when you slice the string from 2:end you would have got half of the first character (witch is invalid and you get an error).
The solution is to get the second valid index instead of 2 in the slice. I think that is something like str[nextind(str, 1):end]
PS. Sorry for a less than clear answer on my phone.
EDIT:
I tried this, and it seems like SubString{UTF8String} and UTF8String has different behaviour on slicing. I've reported it as bug #7811 on GitHub.
I have a text filed which allows user to input numbers. This is what I did:
[_textfield setText:[NSString stringWithFormat:#"%d", [_textfield.text intValue]]];
Basically, I convert text in text filed to integer, then convert back to string. This will ensure the text is numbers only.
Now I need to store the text in _textfield into core data. I was wondering wether should use string as the attribute type or integer.
I know integer is a more sensible option. But to this case, every time the view is loaded, I need fetch this data and set to the _textfield. If I use integer as the attribute type, I have to convert to string each time. I know what I need to do is simply:
_textfield.text = [numberFromCoreData stringValue];
I don't need to compare, sort or do any arithmetic computation with that number, so should I just use string as the attribute type?
Integer searching is significantly faster than string searching. That is the single most compelling reason to use numbers in your persistence layer. Numbers also can sort differently than strings.
For performance reasons I would never use a string when I know the value is always going to be an integer. Control the input, force it to only accept numbers and keep your data integrity.
It depends how you need to use that field. In almost every case, integer data should be stored as an integer type, but not always. You definitely want an integer type if you'll ever be using that field in a case where its numeric value counts in some way. That includes sorting (because it's a hell of a lot faster with numeric fields), comparing numeric values, or any kind of mathematical operation.
But there's are exceptions. For example, in some cases fields which initially seem to be inherently numeric turn out not to be so. Like a "size" field which is normally an integer. But on closer inspection it turns out that some sizes are specified as "8 - 10", "12 - 14", etc. This happened in one app I worked on a couple of years ago. In that case I ended up using two fields for the data-- a numeric "sortSize" that could be used for sorting, and a string "displaySize" that included the full string.
It's probably not what you want but why don't you use a keyboard type "number Pad" for your textfield?
With that, you would be sure that you have only numbers into your textfield.
Honestly I can't think of a compelling reason. Strings in general take up more storage space than Integers but in the modern world of computing this isn't much of an issue. If you aren't really pushing you processor too hard I'd go with what is convenient.
From the most basic way of thinking about it an integer is a number but for a string the computer needs to know when the string ends, starts, and what is in it so its a little bigger.
I have a field in my Rails model that has max length 255.
I'm importing data into it, and some times the imported data has a length > 255. I'm willing to simply chop it off so that I end up with the largest possible valid string that fits.
I originally tried to do field[0,255] in order to get this, but this will actually chop trailing Unicode right through a character. When I then go to save this into the database, it throws an error telling me I have an invalid character due to the character that's been halved or quartered.
What's the recommended way to chop off Unicode characters to get them to fit in my space, without chopping up individual characters?
Uh. Seems like truncate and friends like to play with chars, but not their little cousins bytes. Here's a quick answer for your problem, but I don't know if there's a more straighforward and elegant question I mean answer
def truncate_bytes(string, size)
count = 0
string.chars.take_while{|c| (a += c.bytes.to_a.length) <= size }.join
end
Give a look at the Chars class of ActiveSupport.
Use the multibyte proxy method (mb_chars) before manipulating the string:
str.mb_chars[0,255]
See http://api.rubyonrails.org/classes/String.html#method-i-mb_chars.
Note that until Rails 2.1 the method was "chars".
How do you calculate the length of the string that would be returned by Array::pack? Is there something like Python's calcsize?
array.pack("").count I would say. Not really the fastest method, but it works.
By making an interpreter complying to the specifications found in Array::pack.
Or, reusing the existing implementation to count the number of characters instead of appending them to a string.