Java Class getConstructor() Method

The getConstructor() method of java Class class returns a Constructor object that reflects the public constructor of the class.

Syntax

public Constructor<T> getConstructor(Class<?>... parameterTypes) throws NoSuchMethodException,  SecurityException

Parameter

parameterTypes - the parameter array.

Returns

Constructor object.

Throws

NoSuchMethodException , SecurityException

Example 1

//import statements
import java.lang.reflect.*;

public class ClassgetConstructorExample1 {

   public static void main(String[] args) {

      try {
         
         Class clsarray[] = new Class[] { String.class };  //creating array
         Constructor cnstrctr = String.class.getConstructor(clsarray); //get the constructor
         System.out.println(cnstrctr); //print the constructor
      } catch(Exception e) {
         System.out.println(e); //print exception object
      } 
   }
}

Test it Now

Output:

public java.lang.String(java.lang.String)   //class path

Example 2

//import statements.....
import java.lang.reflect.Constructor;
import java.math.BigInteger;  //import

public class ClassgetConstructorExample2 {

    public static void main(String... args) throws NoSuchMethodException {
        Class1 def = new Class1();
         Class1 prm = new Class1(23);
        Class<Class1> cls = Class1.class;
        Constructor<Class1> constr = cls.getConstructor();  //get the default constructor
        System.out.println(constr);  //print the constructor


        constr = cls.getConstructor(int.class); //get  the constructor with parameter of type int
        System.out.println(constr);  //print the constructor

        constr = cls.getConstructor(String.class, BigInteger[].class);  //get the constructor with 2 parameter
        System.out.println(constr);  //print the constructor
    }

    private static class Class1 {
        public Class1() {
            System.out.println("the Default Constructor... "); //default  constructor
        }

        public Class1(int x) {
            System.out.println("this is Parameterized Constructor....(one parameter) ");
        }

        public Class1(String s, BigInteger[] integers) {   //take 2 parameter
            System.out.println("the Parameterized Constructor....(multiple parameter) ");
        }
    }
}

Test it Now

Output:

Default Constructor... 
Parameterized Constructor....(one parameter) 
public ClassgetConstructorExample2$Class1()
public ClassgetConstructorExample2$Class1(int)
public ClassgetConstructorExample2$Class1(java.lang.String,java.math.BigInteger[])

Next TopicJava Class

← prev next →