How to write nullable int in java?

I want to convert a web form to a model in Java.

In C# I can write this:

<input name="id" value="" type="text"/>


public class Test
{
    public int? Id{get;set;}
}

The id can be null.

But in Java when using struts2 it throws an exception:

Method "setId" failed

So how to write this case in Java?

Instead of using int you can use Integer (Integer javadoc) because it is a nullable Java class.

You can use an Integer, which is a reference type (class)in Java and therefore nullable.

Int32 (or int) is a struct (value type) in C#. In contrast, Integer in Java is a class which wraps an int. Instances of reference types can be null, which makes Integer an legit option.

Nullable<T> in .NET gives you similar options because it enables you to treat a value type like a nullable type. However, it's still different from Java's Integer since it's implemented as a struct (value type) which can be compared to null, but cannot actually hold a genuine null reference.

In Java, just use Integer instead of int. This is essentially a nullable int. I'm not too familiar with Struts, but using Integer should allow you to omit the value.