Question

How does one convert an empty string to an int using Struts2. When the application encounters this parameter with no value, like from an empty text field, it throws the following exception.

java.lang.NoSuchMethodException:
com.XXXXXXXXXXXX.setID([Ljava.lang.String;)

Where ID is an integer, and the URL is:

Something.action?ID=&other=rawr

Is there a way to do this without using an Integer (class)? Do I have to write a type converter?

Answer 1

If you declare your id parameter as Integer struts will convert the empty string to null.

public void setId(Integer id){ 
...
}

From : http://struts.apache.org/2.0.14/docs/type-conversion.html#TypeConversion-NullandBlankValues

Null and Blank Values

Some properties cannot be set to null.
Primitives like boolean and int cannot
be null. If your action needs to or
will accept null or blank values, use
the object equivalents Boolean and
Integer. Similarly, a blank string “”
cannot be set on a primitive. At the
time of writing, a blank string also
cannot be set on a BigDecimal or
BigInteger. Use server-side validation
to prevent invalid values from being
set on your properties (or handle the
conversion errors appropriately).