Program/Source Code:

The source code to implement default or no-argument constructor is given below. The given program is compiled and executed successfully.

// Java program to implement default 
// or no-argument constructor

class Sample {
  int num1;
  int num2;

  Sample() {
    num1 = 10;
    num2 = 20;
  }

  void printValues() {
    System.out.println("Num1: " + num1);
    System.out.println("Num2: " + num2);
  }
}

class Main {
  public static void main(String args[]) {
    Sample obj = new Sample();
    obj.printValues();
  }
}

Output:

Num1: 10
Num2: 20

Explanation:

In the above program, we created a Sample class and public class Main. The Sample class contains data members num1, num2, and a default constructor, a method printValues(). Here, we initialized data members using the default constructor.

The Main class contains a static method main(). The main() is an entry point for the program. Here, we created object obj and called the printValues() method to print values of data members.