Class getDeclaredMethod() method in Java with Examples

The getDeclaredMethod() method of java.lang.Class class is used to get the specified method of this class with the specified parameter type. The method returns the specified method of this class in the form of Method object.

Syntax:

public Method getDeclaredMethod(String methodName, 
                            Class[] parameterType)
       throws NoSuchMethodException, SecurityException

Parameter: This method accepts two parameters:

• methodName which is the Method to be get.
• parameterType which is the array of parameter type for the specified method.

Return Value: This method returns the specified method of this class in the form of Method objects.

Exception This method throws:

• NoSuchMethodException if a method 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 getDeclaredMethod() method.

  Example 1:

  // Java program to demonstrate
  // getDeclaredMethod() method
  
  import java.util.*;
  
  public class Test {
  
      public void func() {}
  
      public static void main(String[] args)
          throws ClassNotFoundException, NoSuchMethodException
      {
  
          // returns the Class object for this class
          Class myClass = Class.forName("Test");
  
          System.out.println("Class represented by myClass: "
                             + myClass.toString());
  
          String methodName = "func";
          Class[] parameterType = null;
  
          // Get the method of myClass
          // using getDeclaredMethod() method
          System.out.println(
              methodName + " Method of myClass: "
              + myClass.getDeclaredMethod(
                    methodName, parameterType));
      }
  }
  Output:

  Class represented by myClass: class Test
  func Method of myClass: public void Test.func()
  

  Example 2:

  // Java program to demonstrate
  // getDeclaredMethod() method
  
  import java.util.*;
  
  class Main {
  
      private void func() {}
  
      public static void main(String[] args)
          throws ClassNotFoundException, NoSuchMethodException
      {
          // returns the Class object for this class
          Class myClass = Class.forName("Main");
  
          System.out.println("Class represented by myClass: "
                             + myClass.toString());
  
          String methodName = "func";
          Class[] parameterType = null;
  
          try {
              // Get the method of myClass
              // using getDeclaredMethod() method
              System.out.println(
                  methodName + " Method of myClass: "
                  + myClass.getDeclaredMethod(
                        methodName, parameterType));
          }
          catch (Exception e) {
              System.out.println(e);
          }
      }
  }
  Output:

  Class represented by myClass: class Main
  func Method of myClass: private void Main.func()
  

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