ObjectStreamClass getFields() in Java

getFields(): This method is available in the java.io.ObjectStreamClass class of Java.

Syntax:

ObjectStreamField[] java.io.ObjectStreamClass.getFields()

This method returns an array of the fields of this serializable class.

Parameters: NA

Returns: an array containing an element for each persistent field of this class.

Note: Returns an array of length zero if there are no fields.

Exceptions: NA

Approach 1: When an empty array is a return

Java

import java.io.ObjectStreamClass;
import java.util.Arrays;

public class ObjectStreamClassgetFields {
    public static void main(String[] args) {

        ObjectStreamClass objectStreamClass =
                     ObjectStreamClass.lookup(String.class);

        System.out.println(Arrays.toString(objectStreamClass.getFields()));
    }
}

Output:

[]

Approach 2: When some fields are returned

Java

import java.io.ObjectStreamClass;
import java.util.ArrayList;
import java.util.Arrays;

public class ObjectStreamClassgetFields {
    public static void main(String[] args) {

        ObjectStreamClass objectStreamClass = 
                 ObjectStreamClass.lookup(ArrayList.class);

        System.out.println(Arrays.toString(objectStreamClass.getFields()));
    }
}

Output:

[I size]

Some more methods of ObjectStreamClass

forClass(): This method returns the class to the local VM that this version is mapped to.

getField(String): This method gets the field of this class by name.

getName(): This method returns the name of the class described by this descriptor.

getSerialVersionUID(): This method returns the serialVersionUID for this class.

lookup(Class): This method creates an ObjectStreamClass instance if one does not exist yet for the class.

lookupAny(Class): This method returns the descriptor for any class, regardless of whether it implements Serializable.

toString(): This method returns a string describing this ObjectStreamClass.