setByte() method of java.lang.reflect.Field used to set the value of a field as a byte on the specified object. When you need to set the value of a field of an object as byte then you can use this method to set value over an Object. Syntax:
public void setByte(Object obj, byte b)
throws IllegalArgumentException,
IllegalAccessException
Parameters: This method accepts  two parameters:
- obj: which is the object whose field should be modified and
- b: which is the new value for the field of obj being modified.
Return: This method returns nothing. Exception: This method throws the following Exception:
- IllegalAccessException: if this Field object is enforcing Java language access control and the underlying field is either inaccessible or final.
- IllegalArgumentException: if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementer thereof), or if an unwrapping conversion fails.
- NullPointerException: if the specified object is null and the field is an instance field.
- ExceptionInInitializerError: if the initialization provoked by this method fails.
Below programs illustrate setByte() method: Program 1:Â
Java
// Java program to illustrate setByte() methodÂ
import java.lang.reflect.Field;Â
public class GFG {Â
    public static void main(String[] args)        throws Exception    {Â
        // create user object        Employee emp = new Employee();Â
        // print value of leaveLeft        System.out.println(            "Value of leaveLeft before "            + "applying setByte is "            + emp.leaveLeft);Â
        // Get the marks field object        Field field            = Employee.class                  .getField("leaveLeft");Â
        // Apply setByte Method        field.setByte(emp, (byte)2);Â
        // print value of leaveLeft        System.out.println(            "Value of leaveLeft after "            + "applying setByte is "            + emp.leaveLeft);Â
        // print value of age        System.out.println(            "Value of age before "            + "applying setByte is "            + emp.age);Â
        // Get the marks field object        field = Employee.class.getField("age");Â
        // Apply setByte Method        field.setByte(emp, (byte)56);Â
        // print value of age        System.out.println(            "Value of age after "            + "applying setByte is "            + emp.age);    }}Â
// sample classclass Employee {Â
    // static byte values    public static byte age = 45;    public static byte leaveLeft = 12;} |
Output:
Value of leaveLeft before applying setByte is 12 Value of leaveLeft after applying setByte is 2 Value of age before applying setByte is 45 Value of age after applying setByte is 56
Program 2:Â
Java
// Java program to illustrate setByte() methodÂ
import java.lang.reflect.Field;Â
public class GFG {Â
    public static void main(String[] args)        throws Exception    {Â
        // create user object        User user = new User();Â
        // Get the id field object        Field field = User.class                          .getField("id");Â
        // Apply setByte Method        field.setByte(user, (byte)20);Â
        // print value of isActive        System.out.println(            "Value after "            + "applying setByte is "            + user.id);    }}Â
// sample User classclass User {Â
    // static byte values    public static byte id = 2;} |
Output:
Value after applying setByte is 20
