CODEWITHSUNDEEP
javanumberformatexception
Namita
Namita

Reputation: 779

unable to understand the cause of Number Format Exception

I have written a small program in which a user enters minutes and program shows the current Date and Time + minutes entered by the user. 

final String DATE_FORMAT_NOW = "MM/dd/yyyy HH:mm:ss";
final DateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss", Locale.US);

Calendar cal = Calendar.getInstance();
cal.add(Calendar.MINUTE, Integer.valueOf(sample.getMinutes()));

SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
String dt = sdf.format(cal.getTime());

System.out.println(" Date and time with added Minutes : " + (dateFormat.parse(dt));

Sample

private String minutes;

//getter and setter

I am getting this exception

java.lang.NumberFormatException: For input string: ""

What I am doing wrong here? Should I use 

Integer.parseInt

or 

Integer.valueOf(Integer.parseInt(sample.getMinutes())));?

Upvotes: 2

Views: 2617

Answers (9)

user1397872
user1397872

Reputation: 49

  1. With current date and time.

    public static void main(String[] args) 
{
    try 
    {
        final String DATE_FORMAT_NOW = "MM/dd/yyyy HH:mm:ss";
        final DateFormat dateFormat  = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss", Locale.US);

        Date sample  = new Date();
        int iMinutes = 30;//minutes added by the user

        Calendar cal = Calendar.getInstance();

        cal.add(Calendar.MINUTE, Integer.valueOf(sample.getMinutes()));

        SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
        String dt            = sdf.format(cal.getTime());

        System.out.println("Current Date and time:"+sample);
        System.out.println("Date and time with added Minutes : " + (dateFormat.parse(dt)));
    } 
    catch (ParseException ex) 
    {
        Logger.getLogger(NewMain.class.getName()).log(Level.SEVERE, null, ex);
    }
}

    The output will be displays as:
    Current Date and time:Tue Jun 12 15:57:55 IST 2012
    Date and time with added Minutes : Tue Jun 12 16:54:55 IST 2012
    Here the minutes "57" was added to the calendar and the time has moved forward by "30" mins.And that is the your result(Date and time with added Minutes).

  2. With user in input minutes.

    public static void main(String[] args) 
{
    try 
    {
        final String DATE_FORMAT_NOW = "MM/dd/yyyy HH:mm:ss";
        final DateFormat dateFormat  = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss", Locale.US);

        int iMinutes = 30;//minutes added by the user

        Calendar cal = Calendar.getInstance();

        cal.add(Calendar.MINUTE, iMinutes);

        SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
        String dt            = sdf.format(cal.getTime());

        System.out.println("Current Date and time:"+sample);
        System.out.println("Date and time with added Minutes : " + (dateFormat.parse(dt)));
    } 
    catch (ParseException ex) 
    {
        Logger.getLogger(NewMain.class.getName()).log(Level.SEVERE, null, ex);
    }
}

    This will work as per your desire first you take the minutes from the user and assign that minutes to the "iMinutes" variable of the code it will add that much minutes to the calander.

    The output will be displayed as:
    Current Date and time:Tue Jun 12 16:07:55 IST 2012
    Date and time with added Minutes : Tue Jun 12 16:37:55 IST 2012

And if you want to set the minutes then use "set" instead of "add" in the "cal.add".

Hope this will solve your problem.
Regards.

Upvotes: 1

Michael Farouk
Michael Farouk

Reputation: 11

Check if the returned string from sample.getMinutes() is a number or not. It must be a number without any white space to be parsed, otherwise you will get a NumberFormatException.

Upvotes: 1

Kuldeep Jain
Kuldeep Jain

Reputation: 8598

There is nothing unusal here. Read the java docs for parseInt() and valueOf which clearly states that a NumberFormatException is thrown if the String does not contain a parsable integer. And an empty string "" is not a parsable int.

It is up to you how you handle such cases for which a NumberFormatException is thrown.

Upvotes: 0

kornero
kornero

Reputation: 1069

Add some sort of checking:

final String DATE_FORMAT_NOW = "MM/dd/yyyy HH:mm:ss";
final DateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss", Locale.US);

Calendar cal = Calendar.getInstance();
final String minutes = sample.getMinutes()
cal.add(Calendar.MINUTE, Integer.valueOf((minutes != null && !minutes.isEmpty()) ? minutes : 0);

SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
String dt = sdf.format(cal.getTime());

System.out.println(" Date and time with added Minutes : " + (dateFormat.parse(dt));

Upvotes: 0

Balaswamy Vaddeman
Balaswamy Vaddeman

Reputation: 8530

java.lang.NumberFormatException: For input string: ""

input String "" can not be converted into valid Integer.

before using Integer.parseInt, you ensure you are getting an integer by the following ways.

1.provide javascript validation for checking int

or/and

2.provide a server side validation for checking non-integer Strings

also see how to avoid NumberFormatException

Upvotes: 0

Matthias Bruns
Matthias Bruns

Reputation: 900

java.lang.NumberFormatException: For input string: ""

Seems like you never set the minutes String

Upvotes: 0

Thilo
Thilo

Reputation: 262504

java.lang.NumberFormatException: For input string: ""

An empty String cannot be parsed to a number.

You need to check it first (using something like String#length() or StringUtils#isBlank()) and decide what to do with this case (for example treat it as zero).

Upvotes: 0

Sunil Kumar B M
Sunil Kumar B M

Reputation: 2795

"" is an empty string and it cannot be parsed into a valid integer given any circumstances

Upvotes: 0

David Grant
David Grant

Reputation: 14223

The problem you're having is that an empty string is not a valid integer. Your application should catch the exception, and set a sensible default instead.

Upvotes: 0

Related Questions