Class getDeclaredField() method in Java with Examples - GeeksforGeeks

16 Dec, 2019
The getDeclaredField() method of java.lang.Class class is used to get the specified field of this class. The method returns the specified field of this class in the form of Field object.
Syntax:
public Field getDeclaredField(String fieldName)
       throws NoSuchMethodException,
              SecurityException

Parameter: This method accepts a parameter fieldName which is the Field to get.
Return Value: This method returns the specified field of this class in the form of Field objects.
Exception This method throws:
NoSuchFieldException if a field with the specified name is not found.
NullPointerException if name is null
SecurityException if a security manager is present and the security conditions are not met.Below programs demonstrate the getDeclaredField() method.Example 1:// Java program to demonstrate// getDeclaredField() method  import java.util.*;  public class Test {      public Object obj;      public static void main(String[] args)        throws ClassNotFoundException, NoSuchFieldException    {          // returns the Class object for this class        Class myClass = Class.forName("Test");          System.out.println("Class represented by myClass: "                           + myClass.toString());          String fieldName = "obj";          // Get the field of myClass        // using getDeclaredField() method        System.out.println(            fieldName + " Field of myClass: "            + myClass.getDeclaredField(fieldName));    }}Output:Class represented by myClass: class Test
obj Field of myClass: public java.lang.Object Test.obj
Example 2:// Java program to demonstrate// getDeclaredField() method  import java.util.*;  class Main {      private Object obj;      public static void main(String[] args)        throws ClassNotFoundException, NoSuchFieldException    {          // returns the Class object for this class        Class myClass = Class.forName("Main");          System.out.println("Class represented by myClass: "                           + myClass.toString());          String fieldName = "obj";          try {            // Get the field of myClass            // using getDeclaredField() method            System.out.println(                fieldName + " Field of myClass: "                + myClass.getDeclaredField(fieldName));        }        catch (Exception e) {            System.out.println(e);        }    }}Output:Class represented by myClass: class Main
obj Field of myClass: private java.lang.Object Main.obj
Reference: https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#getDeclaredField-java.lang.String-My Personal Notes
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Below programs demonstrate the getDeclaredField() method.
Example 1:
// Java program to demonstrate// getDeclaredField() method  import java.util.*;  public class Test {      public Object obj;      public static void main(String[] args)        throws ClassNotFoundException, NoSuchFieldException    {          // returns the Class object for this class        Class myClass = Class.forName("Test");          System.out.println("Class represented by myClass: "                           + myClass.toString());          String fieldName = "obj";          // Get the field of myClass        // using getDeclaredField() method        System.out.println(            fieldName + " Field of myClass: "            + myClass.getDeclaredField(fieldName));    }}
Class represented by myClass: class Test
obj Field of myClass: public java.lang.Object Test.obj

Example 2:
// Java program to demonstrate// getDeclaredField() method  import java.util.*;  class Main {      private Object obj;      public static void main(String[] args)        throws ClassNotFoundException, NoSuchFieldException    {          // returns the Class object for this class        Class myClass = Class.forName("Main");          System.out.println("Class represented by myClass: "                           + myClass.toString());          String fieldName = "obj";          try {            // Get the field of myClass            // using getDeclaredField() method            System.out.println(                fieldName + " Field of myClass: "                + myClass.getDeclaredField(fieldName));        }        catch (Exception e) {            System.out.println(e);        }    }}
Class represented by myClass: class Main
obj Field of myClass: private java.lang.Object Main.obj

Reference: https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#getDeclaredField-java.lang.String-
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