1. Introduction

In this blog post, we will walk through a simple Java program that checks whether a given number is positive or negative. A number is positive if it is greater than zero and negative if it is less than zero.

2. Program Steps

1. Import the Scanner class from the java.util package for user input.

2. Define the main class named NumberChecker.

3. Inside the main class, define the main method.

4. Inside the main method, create an object of the Scanner class for user input.

5. Prompt the user to enter a number.

6. Check whether the entered number is positive, negative, or zero.

7. Print the result, indicating whether the number is positive, negative, or zero.

3. Code Program

import java.util.Scanner; // 1. Importing Scanner for user input

public class NumberChecker { // 2. Defining the main class

    public static void main(String[] args) { // 3. Defining the main method

        Scanner input = new Scanner(System.in); // 4. Creating Scanner object for user input

        System.out.print("Enter a number: "); // 5. Prompting user to enter a number
        double number = input.nextDouble(); // Receiving the number

        if (number > 0) { // 6. Checking if the number is positive
            System.out.println("The entered number is positive."); // 7. Printing result
        } else if (number < 0) { // 6. Checking if the number is negative
            System.out.println("The entered number is negative."); // 7. Printing result
        } else { // 6. Checking if the number is zero
            System.out.println("The entered number is zero."); // 7. Printing result
        }

        input.close(); // Closing the Scanner object to avoid memory leak
    }
}

Output:

Enter a number: -5
The entered number is negative.

4. Step By Step Explanation

– Step 1: The Scanner class from the java.util package is imported to facilitate user input.

– Step 2: The main class named NumberChecker is defined.

– Step 3: The main method, which is the entry point of the program, is defined inside the main class.

– Step 4: A Scanner object named "input" is created to take user input.

– Step 5: The user is prompted to enter a number. For this example, the user enters -5.

– Step 6: The program then checks if the entered number is greater than, less than, or equal to zero, determining whether it is positive, negative, or zero, respectively.

– Step 7: Based on the condition met, the program prints out whether the entered number is positive, negative, or zero. In this case, since -5 is less than zero, the output is "The entered number is negative."

– Lastly, the Scanner object is closed to avoid any potential memory leak.