Field setChar() method in Java with Examples

setChar() method of java.lang.reflect.Field used to set the value of a field as a char on the specified object. When you need to set the value of a field of an object as char then you can use this method to set value over an Object.

Syntax:

public void setChar(Object obj, char c)
            throws IllegalArgumentException,
                   IllegalAccessException

Parameters: This method accepts accepts two parameters:

  • obj: which is the object whose field should be modified and
  • c: 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 implementor 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 setChar() method:
Program 1:

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// Java program to illustrate setByte() method
  
// program illustrate setChar()
import java.lang.reflect.Field;
  
public class GFG {
  
    public static void main(String[] args)
        throws Exception
    {
  
        // create user object
        Employee emp = new Employee();
  
        // print value of lastNamePrefix
        System.out.println(
            "Value of lastNamePrefix before "
            + "applying setChar is "
            + emp.lastNamePrefix);
  
        // Get the marks field object
        Field field = Employee.class
                          .getField("lastNamePrefix");
  
        // Apply setChar Method
        field.setChar(emp, 'B');
  
        // print value of lastNamePrefix
        System.out.println(
            "Value of lastNamePrefix after "
            + "applying setChar is "
            + emp.lastNamePrefix);
  
        // print value of firstNamePrefix
        System.out.println(
            "Value of firstNamePrefix before "
            + "applying setChar is "
            + emp.firstNamePrefix);
  
        // Get the marks field object
        field = Employee.class
                    .getField("firstNamePrefix");
  
        // Apply setChar Method
        field.setChar(emp, 'Z');
  
        // print value of firstNamePrefix
        System.out.println(
            "Value of firstNamePrefix after "
            + "applying setChar is "
            + emp.firstNamePrefix);
    }
}
  
// sample class
class Employee {
  
    // static char values
    public static char firstNamePrefix = 'A';
    public static char lastNamePrefix = 'S';
}

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Output:

Value of lastNamePrefix before applying setChar is S
Value of lastNamePrefix after applying setChar is B
Value of firstNamePrefix before applying setChar is A
Value of firstNamePrefix after applying setChar is Z

Program 2:

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// Java program to illustrate setChar() method
  
import java.lang.reflect.Field;
  
public class GFG {
  
    public static void main(String[] args)
        throws Exception
    {
  
        // create user object
        User user = new User();
  
        // Get the id field object
        Field field = User.class
                          .getField("id");
  
        // Apply setChar Method
        field.setChar(user, 'A');
  
        // print value of isActive
        System.out.println("Value after "
                           + "applying setChar is "
                           + user.id);
    }
}
  
// sample User class
class User {
  
    // static char values
    public static char id = 'Z';
}

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Output:

Value after applying setChar is A

Reference: https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#setChar-java.lang.Object-char-

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