CODEWITHSUNDEEP
javaexception
Madde
Madde

Reputation: 473

Is it possible to check for java.lang.NumberFormatException?

Is it possible to check for a NumberFormatException for input string: ""?

I tried to write my program so that if the user didn't put in any values an error message would come out instead of NumberFormatException:

if(pasientNavnFelt.getText() == "" || pasientNrFeIt.getText() == "")
{
  utskriftsområde.setText("ERROR, insert values");
}

if(pasientNavnFelt.getText() != "" || pasientNrFeIt.getText() != "")
{ 
  // rest of code here if the program had values in it
}

I also tried with null:

if(pasientNavnFelt.getText() == null || pasientNrFeIt.getText() == null)
{
  utskriftsområde.setText("ERROR, insert values");
}

if(pasientNavnFelt.getText() != null || pasientNrFeIt.getText() != null)
{ 
  // rest of code here if the program had values in it
}

I still get:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""

The program works fine if it has values.

Upvotes: 0

Views: 3703

Answers (3)

James
James

Reputation: 8586

Your second if condition is wrong. You're trying to say, if there's a null, error, else do something. You're saying if there's a null error, then if either of them is not null, do the rest. The two character change is change the second "||" to a "&&". But what you probably want is actually:

   if(pasientNavnFelt.getText() == null || pasientNrFeIt.getText() == null)
        {
            utskriftsområde.setText("ERROR, insert values");
        }
   else 
       { <rest of code here if the program had values in it>}

Upvotes: 0

JB Nizet
JB Nizet

Reputation: 691755

Never compare Strings with ==. == checks that the two objects are the same, and not that the two objects have the same characters. Use equals() to compare strings.

That said, to validate that a string is a valid Integer, you indeed need to catch the exception:

try {
    int i = Integer.parseInt(s);
    // s is a valid integer
}
catch (NumberFormatException e) {
    // s is not a valid integer
}

This is basic Java stuff. Read the Java tutorial over exceptions.

Upvotes: 2

Aubin
Aubin

Reputation: 14853

Try:

if( pasientNavnFelt.isEmpty() || pasientNrFeIt.isEmpty()) {
   utskriftsområde.setText("ERROR, insert values");
}
else {
   ...
}

Upvotes: 1

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