Field class in Reflection API
Introduction
- Field class in Java is part of the Reflection API and represents a single field (variable) of a class.
-
It is present in the
java.lang.reflectpackage. -
The
Fieldclass allows you to get information about, and manipulate, fields of objects at runtime. - It provides methods to get metadata about a field, such as its name, type, modifiers, and also allows getting and setting field values dynamically.
-
Fieldclass inherits theMemberinterface:
Important Methods of Field Class
-
Below are some important methods of
Fieldclass:- -
S.No Method Use 1 getName()Returns the name of the field. 2 getType()Returns the data type ( Classobject) of the field.3 getModifiers()Returns the Java language modifiers (public, private, static, etc.) as an int. 4 get(Object obj)Returns the value of the field for the given object instance. 5 set(Object obj, Object value)Sets the value of the field for the given object instance. 6 isSynthetic()Checks if the field is compiler-generated (synthetic). -
Program:
import java.lang.reflect.*; class Student { public String name; private int age; public Student() {} } public class MainApp { public static void main(String[] args) throws Exception { Student s = new Student(); Class<?> c = Student.class; // Get declared fields for (Field field : c.getDeclaredFields()) { System.out.println("\nField Name: " + field.getName()); System.out.println("Type: " + field.getType().getSimpleName()); System.out.println("Modifiers: " + Modifier.toString(field.getModifiers())); System.out.println("Is Synthetic: " + field.isSynthetic()); // Access private fields field.setAccessible(true); // Set value dynamically if (field.getType() == String.class) field.set(s, "John"); else if (field.getType() == int.class) field.set(s, 25); // Get value dynamically System.out.println("Value: " + field.get(s)); } } }Output:
Field Name: name Type: String Modifiers: public Is Synthetic: false Value: John Field Name: age Type: int Modifiers: private Is Synthetic: false Value: 25
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