Setting null value to integer

Question

How can i set null to integer variable initially instead of "0". I know already by default all int value is "0". I used String.valueOf() method etc. I dont want to print as "null". I want to print blank like " ". I get number format exception. Please give one solution for that.

Thanks in advance

Here is the code

public class IntegerDemo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String id="";


        System.out.println(""+Integer.parseInt(id));

    }
}

if(Integer.parseInt(id)==0){ System.out.println(" ");}

Venkat
– Venkat

2013-08-31 05:24:26 +00:00
Commented Aug 31, 2013 at 5:24 — Venkat
– Venkat, Commented Aug 31, 2013 at 5:24

dharam · Accepted Answer · 2013-08-31 05:08:29Z

4

I am sure you are over-complicating the problem, it is a real simple thing to do. Check the code below:

Integer i = null;
System.out.println(i == null ?"":i);

answered Aug 31, 2013 at 5:08

dharam

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Comments

Suresh Atta · Accepted Answer · 2013-08-31 04:55:29Z

4

Use Integer wrapper class instead of primitive

Integer myInt= null;

For object references you can set null.But you cannot to primitives.

answered Aug 31, 2013 at 4:55

Suresh Atta

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Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

Creating an instance of Integer with its primary value as null is meaningless, but you can do this on declaration:

Integer id = null;

The reason you're getting NumberFormatException is laid out in the documentation:

An exception of type NumberFormatException is thrown if any of the following situations occurs:

The first argument is null or is a string of length zero.

The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.

Any character of the string is not a digit of the specified radix, except that the first > character may be a minus sign '-' ('\u002D') or plus sign '+' ('\u002B') provided that the string is longer than length 1.

The value represented by the string is not a value of type int.

You can't call Integer.parseInt("") or Integer.parseInt(null), with that limitation.

commit · Accepted Answer · 2013-08-31 05:21:16Z

0

If you parse null or blank as int it will throw numberFormatException. Check for that before parsing:

try{
   System.out.println(StringUtils.isNotBlank(id)?Integer.parseInt(id):"");
}
catch(NumberFormatException e){
   System.out.println("Not A Number");
}

Also be sure if string has not number by catching exception. StringUtils.isNotBlank() will check for both null as well as blank.

answered Aug 31, 2013 at 5:21

commit

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Comments

ced-b · Accepted Answer · 2013-08-31 14:28:23Z

0

You would have to stick with the java.lang.Integer class.

String id = ""
Integer test = null;

if (!"".equals(id))
{
   test = Integer.parseInt(id);
}

edited Aug 31, 2013 at 14:28

answered Aug 31, 2013 at 4:56

ced-b

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1 Comment

Rohit Jain Over a year ago

parseInt is the method.

Bhaskara Arani · Accepted Answer · 2020-10-26 19:39:03Z

0

Instead of parse, we can use Integer.valueOf(null);

answered Oct 26, 2020 at 19:39

Bhaskara Arani

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Comments

inteloid · Accepted Answer · 2013-08-31 04:55:38Z

-1

Integer int = null;

ints are primitives, they have default values different from null.

answered Aug 31, 2013 at 4:55

inteloid

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2 Comments

Makoto Over a year ago

int is a reserved keyword; this isn't valid Java syntax. Besides, the OP isn't referring to primitives.

inteloid Over a year ago

Yes, I'm wrong with variable name, but obviously I was not referring to primitives as well.

azz · Accepted Answer · 2013-08-31 05:16:51Z

The simple boxed Integer Integer i = null; has already been supplied. Here is an alternative:

class NullableInt {
    private int value;
    private boolean isNull;
    public NullableInt() { isNull = true; }
    public NullableInt(int value) { 
      this.value = value; 
      isNull = false;
    }
    public NullableInt(String intRep) {
      try { value = Integer.parseInt(intRep);
      } catch (NumberFormatException) {
         isNull = true;
      }
    }
    boolean isNull() { return isNull; }
    void setNull(boolean toNull) { isNull = toNull; }
    void setValue(int value) { this.value = value; }
    int getValue() { return value; }
    @Override 
    public String toString() { return isNull ? "" : value; }
}

NullableInt integer1 = new NullableInt(56);
NullableInt integer2 = new NullableInt();

System.out.pritnln(integer1); // >> "56"
System.out.println(integer2); // >> ""

// and finally, to address the actual question:
String id = "";
System.out.println(new NullableInt(id)); // >> ""

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