Recursive Constructor Invocation in Java

Last Updated : 26 Sep, 2021

The process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called a recursive function. In the recursive program, the solution to the base case is provided and the solution of the bigger problem is expressed in terms of smaller problems. Here recursive constructor invocation and stack overflow error in java. It is as shown below in the example as follows:

Example

Java

// Java Program to Illustrate Recursion

// Main class
public class GFG {

    static int count = 0;

    // Method 1
    // Recursive method
    static void function()
    {
        count = count + 1;
        if (count <= 5) {

            System.out.println("Call " + count);
            function();
        }
    }

    // Method 2
    // Main driver method
    public static void main(String[] args) { function(); }
}

Output

Call 1
Call 2
Call 3
Call 4
Call 5

Recursive Constructor Invocation

If a constructor calls itself, then the error message "recursive constructor invocation" occurs. The following program is not allowed by the compiler because inside the constructor we tried to call the same constructor. The compiler detects it instantly and throws an error.

Example:

Java

// Java program to Illustrate How Recursive
// Constructor Invocation Error is Occurred

// Main class
class GFG {

    // Constructor of this class
    // Inside we are trying to call the same constructor
    GFG()
    {
        // This keyword refers to same instance itself
        this();
    }

    // Main driver method
    public static void main(String[] args)
    {

        // Creating an object of class inside main()
        GFG obj = new GFG();
    }
}

Output:

Now let us discuss what exactly we do refer to by Stack overflow error and why does it occur. Stack overflow error occurs if we do not provide the proper terminating condition to our recursive function or template, which means it will turn into an infinite loop.

Implementation:

Here we have created a GFG object inside the constructor which is initialized by calling the constructor, which then creates another GFG object which is again initialized by calling the constructor and it goes on until the stack overflows. This can be justified from the illustration as follows:

Example:

Java

// Java program to Illustrate Stack Overflow Error

// Main class
public class GFG {

    // Constructor of this class
    GFG()
    {

        // Creating an object of GFG class inside the
        // constructor which is initialized by calling the
        // constructor, which is initialized by
        // calling the constructor and it goes on
        GFG obj1 = new GFG();
    }

    // Main driver method
    public static void main(String[] args)
    {

        // Creating an object of this class
        GFG obj = new GFG();
    }
}