No Argument Constructor Example

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No Argument Constructor Example

In this section you will learn how to know that whether any class consists No-Argument Constructor or not ?. Here is an example that provides the usage of the newInstance() method in more detail.

In this section you will learn how to know that whether any class consists No-Argument Constructor or not ?. Here is an example that provides the usage of the newInstance() method in more detail.

No Argument Constructor Example

     

In this section you will learn how to know that whether any class consists No-Argument Constructor or not ?. Here is an example that provides the usage of the newInstance() method in more detail.

Here in our example we have used "forName()" static method of Class and then we have invoked newInstance() method to create a new object without any argument. Invoking newInstance() method throws a NoSuchMethodException if the class does not have any no-argument constructor.

Here is code for example:

 

 

 

NoArgConstructor.java

import java.lang.reflect.*;
import java.util.ArrayList;

public class NoArgConstructor {
  public static void main(String str[]){
  try{
 ArrayList list = (ArrayList)
   (
Class.forName("java.util.ArrayList").newInstance());
 System.out.println("No-Argument Constructor exist.");
 System.out.println("New Object created Successfully");
  }catch(Exception e){
  System.out.println("No-argument constructor does not exist.");
  System.out.println(e.getMessage());
  }
 }
}

Output:

Download Source code

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