How can I parse String to int with the default value? [duplicate]

Question

I need to parse a string user id into integer for that I used Integer.parseInt(String s) but it returns null/nil, if there string has/holds non-decimal/integer value and in that case, I need to assign default integer value as 0.

I tried this but it (? 0) seems not working and I don't know whether it is correct syntax or not.

String userid = "user001";
int int_userid = Integer.parseInt(userid) ? 0;

How can assign default value to integer if there is null assignment?

String userid is a parameter argument as part of web service function call, so I cannot update it's data type to integer.

Answer 1

You're most likely using apache.commons.lang3 already:

NumberUtils.toInt(str, 0);

Answer 2

That syntax won't work for Integer.parseInt(), because it will result in a NumberFormatException

You could handle it like this:

String userid = "user001";
int int_userid;
try {
   int_userid = Integer.parseInt(userid);
} catch(NumberFormatException ex) {
   int_userid = 0;
}

Please note that your variable names do not conform with the Java Code Convention

---

A better solution would be to create an own method for this, because I'm sure that you will need it more than once:

public static int parseToInt(String stringToParse, int defaultValue) {
    try {
       return Integer.parseInt(stringToParse);
    } catch(NumberFormatException ex) {
       return defaultValue; //Use default value if parsing failed
    }
}

Then you simply use this method like for e.g.:

int myParsedInt = parseToInt("user001", 0);

This call returns the default value 0, because "user001" can't be parsed.

If you remove "user" from the string and call the method...

int myParsedInt = parseToInt("001", 0);

…then the parse will be successful and return 1 since an int can't have leading zeros!