Call stack behavior in Java - Mini Project: Build & Apply

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Call Stack Behavior

📖 Scenario: Imagine you are baking a layered cake. Each layer depends on the previous one being ready. In programming, functions work similarly using a call stack to keep track of which function is running and what to do next.

🎯 Goal: You will write a simple Java program with three functions calling each other. You will observe how the call stack works by printing messages when entering and exiting each function.

📋 What You'll Learn

Create three functions named first(), second(), and third().

Each function should print a message when it starts and when it ends.

The first() function calls second(), and second() calls third().

Call first() from the main method to start the chain.

💡 Why This Matters

🌍 Real World

Understanding call stack behavior helps when programs call many functions, like in games or apps with multiple features.

💼 Career

Software developers use call stack knowledge to debug errors and optimize program flow.

1

Create the first() function

Write a public static void function called first() that prints "Entering first" when it starts and "Exiting first" when it ends.

Java

public class CallStackDemo {
    public static void main(String[] args) {
        // Your code here
    }

    // Create the first() function below
    // Your code here
}

💡 Need a hint?

Define the first() method inside the CallStackDemo class. Use System.out.println to print messages.

2

Create the second() function and call it from first()

Write a public static void function called second() that prints "Entering second" and "Exiting second". Then, modify first() to call second() between its print statements.

Java

public class CallStackDemo {
    public static void main(String[] args) {
        // Your code here
    }

    public static void first() {
        System.out.println("Entering first");
        // Call second() here
        // Your code here
        System.out.println("Exiting first");
    }

    // Create the second() function below
    // Your code here
}

💡 Need a hint?

Define second() like first(). Inside first(), call second() between the print statements.

3

Create the third() function and call it from second()

Write a public static void function called third() that prints "Entering third" and "Exiting third". Then, modify second() to call third() between its print statements.

Java

public class CallStackDemo {
    public static void main(String[] args) {
        // Your code here
    }

    public static void first() {
        System.out.println("Entering first");
        second();
        System.out.println("Exiting first");
    }

    public static void second() {
        System.out.println("Entering second");
        // Call third() here
        // Your code here
        System.out.println("Exiting second");
    }

    // Create the third() function below
    // Your code here
}

💡 Need a hint?

Define third() like the others. Call third() inside second() between the print statements.

4

Call first() from main() and print the output

In the main method, call the first() function. Run the program to see the order of messages printed, showing how the call stack works.

Java

public class CallStackDemo {
    public static void main(String[] args) {
        // Call first() here
        // Your code here
    }

    public static void first() {
        System.out.println("Entering first");
        second();
        System.out.println("Exiting first");
    }

    public static void second() {
        System.out.println("Entering second");
        third();
        System.out.println("Exiting second");
    }

    public static void third() {
        System.out.println("Entering third");
        System.out.println("Exiting third");
    }
}

💡 Need a hint?

Call first() inside main() to start the chain of function calls.