Class getDeclaredField() method in Java with Examples (original) (raw)

Last Updated : 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:
  import java.util.*;
public class Test {
`public` `Object obj; ` public static void main(String[] args)
`throws` `ClassNotFoundException, NoSuchFieldException ` {
`Class myClass = Class.forName(` `"Test"` `); ` System.out.println( "Class represented by myClass: "
`+ myClass.toString()); ` String fieldName = "obj" ;
`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:
  import java.util.*;
class Main {
`private` `Object obj; ` public static void main(String[] args)
`throws` `ClassNotFoundException, NoSuchFieldException ` {
`Class myClass = Class.forName(` `"Main"` `); ` System.out.println( "Class represented by myClass: "
`+ myClass.toString()); ` String fieldName = "obj" ;
`try` `{ ` 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-

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