# Java Program to Call One Constructor from another

In this article, we will understand how to call one constructor from another. The keyword 'this()' is used to invoke a constructor.

Below is a demonstration of the same. We will displaying sum and product of two numbers while using this() −

Input

Suppose our input is −

The numbers are defined as 12 and 30

Output

The desired output would be −

The sum is: 42
The product is: 360

## Algorithm

Step 1 - START
Step 2 - Declare an integer value namely my_sum
Step 3 - In the main class, we define a ‘this’ reference to the numbers which would be used as input.
Step 4 - This will call the ‘this’ constructor that invokes the current class constructor.
Step 5 - Another ‘display’ function is used to display the sum.
Step 6 - An object of the class is created, and the functions are invoked to display the result

## Example 1

Here, the sum of two numbers is being computed.

public class Main {
int my_sum;
Main() {
this(12, 30);
}
Main(int my_input_1, int my_input_2) {
System.out.println("The numbers are defined as " +my_input_1 +" and " +my_input_2);
this.my_sum = my_input_1 + my_input_2;
}
void display() {
System.out.println("The sum is: " + my_sum);
}
public static void main(String[] args) {
Main my_object = new Main();
my_object.display();
}
}

## Output

The numbers are defined as 12 and 30
The sum is: 42

## Example 2

Here, the product of two numbers is being computed.

public class Main {
int my_product;
Main() {
this(12, 30);
}
Main(int my_input_1, int my_input_2) {
System.out.println("The numbers are defined as " +my_input_1 +" and " +my_input_2);
this.my_product = my_input_1 * my_input_2;
}
void display() {
System.out.println("The product of the two values is: " + my_product);
}
public static void main(String[] args) {
Main my_object = new Main();
my_object.display();
}
}

## Output

The numbers are defined as 12 and 30
The product of the two values is: 360