When I run parseInt:
Integer.parseInt(myString);
it throws:
NumberFormatException: For input string: ""
Does this mean I have do something like this?
if(StringUtils.isNotBlank(myString))
return Integer.parseInt(myString);
else
return 0;
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7 Answers
Yes, but: Wrap it in a thin method (and eliminate the redundant else), or use an existing implementation, like Commons Lang's NumberUtils.toInt(str, defaultValue):
NumberUtils.toInt(myString, 0);
This method handles null values and conversion failures.
Writing the same thing on your own is straight-forward:
- Check for null, and/or...
- ...Wrap the
NumberFormatExtensionexception
Comments
Well, you could use the conditional operator instead:
return StringUtils.isNotBlank(myString) ? Integer.parseInt(myString) : 0;
If you need to do this in multiple places, you'd probably want to put this into a separate method. Note that you should also consider situations where myString is null, or contains non-numeric text.
Comments
If the string can be empty I do it this way:
Integer.parseInt("0" + inputString)
When I'm not sure it contains only digits:
Integer.parseInt(0 + inputString.replaceAll("\\D+",""))
4 Comments
Emil Borconi
I might be a novice but why is this not upvoted at all, such a neat simple trick. Update, just realized why, it fails for negative values!
Yohanes AI
This tricky way only work for unsigned integer (positive number)
Oleg Mikhailov
Correct. For general case I would use some third-party *Utils library (see other answers)
Dave Newton
Blindly replacing non-digits can lead to unexpected behavior in the eyes of the user.
What you have is fine, but as a coding style I prefer to make tests "positive" (isBlank), rather than "negative" (isNotBlank), ie
if (StringUtils.isBlank(myString)) {
return 0;
}
return Integer.parseInt(myString); // Note: No need for else when the if returns
or, more succinctly:
return StringUtils.isBlank(myString) ? 0 : Integer.parseInt(myString);
Comments
Yes. (Validate your inputs before making assumptions about what are in them. :-)
+1 for already finding Apache's common-lang w/ StringUtils.
Comments
Integer.parseInt(String) doesn't accept non-numeric input, including nulls and empty strings.
Either guard against that like you suggested, or catch the NFE.
Comments
I don't know why was I searching for this but here's the easy way:
int test=str.isEmpty()?0:Integer.parseInt(str);
1 Comment
Dave Newton
This will throw an NPE if
str is null.