Java Program to Check if a Number is Positive or Negative – With Examples

Introduction

Checking whether a number is positive, negative, or zero is one of the most fundamental operations in Java. It’s useful in many real-world applications such as data validation, financial analysis, and control systems.

By the end of this tutorial, you’ll know how to:

• Identify if a number is positive, negative, or zero
• Take user input using Scanner
• Use clean if...else branching

Rule: Positive, Negative, or Zero

• A number is positive if number > 0
• Negative if number < 0
• Zero if number == 0

Java Program – Hardcoded Number

public class PositiveNegativeCheck {
    public static void main(String[] args) {
        int number = -15;

        if (number > 0) {
            System.out.println(number + " is positive.");
        } else if (number < 0) {
            System.out.println(number + " is negative.");
        } else {
            System.out.println("The number is zero.");
        }
    }
}

Explanation:

• Basic if...else if...else logic.
• Checks if the number is greater, less than, or equal to zero.

Java Program – User Input with Scanner

import java.util.Scanner;

public class PositiveNegativeInput {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter a number: ");
        double number = scanner.nextDouble();

        if (number > 0) {
            System.out.println(number + " is positive.");
        } else if (number < 0) {
            System.out.println(number + " is negative.");
        } else {
            System.out.println("The number is zero.");
        }

        scanner.close();
    }
}

Works for both integers and decimals.

Java Method – Reusable Function

public class SignChecker {
    public static String checkSign(double num) {
        if (num > 0) return "Positive";
        else if (num < 0) return "Negative";
        else return "Zero";
    }

    public static void main(String[] args) {
        double number = 0.0;
        System.out.println(number + " is " + checkSign(number));
    }
}

Ideal for use in larger programs or modular codebases.

Sample Output

Enter a number: -3.5
-3.5 is negative.

Enter a number: 0
The number is zero.

Enter a number: 12
12.0 is positive.

Summary

In this article, you’ve learned:

• How to check if a number is positive, negative, or zero
• Use of if...else branching in Java
• Input handling with Scanner and method reuse

This logic is foundational for data analysis, logic design, and control flow programming.

FAQ – Java Positive or Negative Check

Does this work for decimal numbers?

Yes, the code supports both int and double.

How can I skip checking for zero?

Remove the else condition and only check > 0 and < 0.

What happens if I enter non-numeric input?

You’ll get an InputMismatchException. Wrap the input in a try-catch block for better error handling.