Largest of Three Numbers Example in Java

Introduction

Largest Of Three Numbers is a classic Java console program that demonstrates the concept with complete source code and sample output. Calculation programs apply formulas to solve geometry, statistics and numeric problems.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Largest Of Three Numbers Example Program

import java.util.Scanner;

class LargestOfThreeNumbers{
	public static void main(String args[]){
		int num1,num2,num3;
		System.out.println("Enter any 3 integers ");
		Scanner in = new Scanner(System.in);
		num1 = in.nextInt();
		num2 = in.nextInt();
		num3 = in.nextInt();
		if ( num1 > num2 && num1 > num3 ){
			System.out.println("num1 is largest.");
		}
		else if ( num2 > num1 && num2 > num3 ){
			System.out.println("num2 is largest.");
		}
		else if ( num3 > num1 && num3 > num2 ){
			System.out.println("num3 is largest.");
		}
		else{
         System.out.println("Entered numbers are not distinct.");
		}
	}
}

Sample Output

Enter any 3 integers
56
78
999
num3 is largest.

When to use

Use these formulas in homework tools, engineering calculators or anywhere repeated numeric computation is needed.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. import java.util.Scanner; imports a class used later in the program.

3. A println / print call writes text to the console — part of the sample output below.

4. A Scanner reads typed input from the keyboard (System.in).

5. num1 = in.nextInt(); updates a variable used in the calculation or output.

6. num2 = in.nextInt(); updates a variable used in the calculation or output.

7. num3 = in.nextInt(); updates a variable used in the calculation or output.

8. The if statement runs the nested code only when the condition is true.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.