Class getConstructor() method in Java with Examples

public Constructor<T>
       getConstructor(Class[] parameterType)
       throws NoSuchMethodException,
              SecurityException

• NoSuchMethodException if a constructor 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 getConstructor() method. Example 1: Java

  // Java program to demonstrate
  // getConstructor() method
  
  import java.util.*;
  
  public class Test {
  
      public Test() {}
  
      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());
  
          Class[] parameterType = null;
  
          // Get the constructor of myClass
          // using getConstructor() method
          System.out.println(
              "Constructor of myClass: "
              + myClass.getConstructor(parameterType));
      }
  }
  

  Output:

  Class represented by myClass: class Test
  Constructor of myClass: public Test()
  

  Example 2: Java

  // Java program to demonstrate
  // getConstructor() constructor
  
  import java.util.*;
  
  class Main {
  
      private Main() {}
  
      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());
  
          Class[] parameterType = null;
  
          try {
              // Get the constructor of myClass
              // using getConstructor() method
              System.out.println(
                  "Constructor of myClass: "
                  + myClass.getConstructor(parameterType));
          }
          catch (Exception e) {
              System.out.println(e);
          }
      }
  }
  

  Output:

  Class represented by myClass: class Main
  java.lang.NoSuchMethodException: Main.<init>()
  

  Reference: https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#getConstructor-java.lang.Class...-
  
  
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  Article Tags :

  • Java
  • Java-lang package
  • Java-Functions
  • Java.lang.Class

  Practice Tags :

  • Java