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javaserializationwrapperprimitive

If declaring member data as primitive data types, will values be serialized if object is declared serializable?

i have a question on whether the use of using primitive data type as opposed to their wrapper counter parts have any due effects on their serialization?

For example, i have a class Person

public class Person implements Serializable{
private int age;
}

as opposed to 

public class Person implements Serializable{
private Integer age;
}

What are their differences?

Solution

  • I'm speaking in terms of Java's Serialization:

    While int is a primitive type, which stores only the value of the variable (in binary), the Integer object (using ObjectOutputStream) will store some "metadata" that when deserialization occurs, it will see the Integer object.

    Yes, serialization not only stores the object, but also the states of the object, so if you store,

    private Integer value = 5;

    The value is "wrapped" (lack of better word) inside Integer and the whole object is stored.

    Added note: In order not to store an object/variable, mark the field with a transient, .e.g

    transient private Integer value = 5;

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