Java program to calculate the area, perimeter and diagonal of a square has been given below. If length of the side of a square is $s~ unit$, the area, perimeter and diagonal of that square would be $s^2~\text{unit}^2$, $4s~\text{unit}$ and $s\sqrt{2}~\text{unit}$ respectively.

For example, if length of the side of a square is $5~cm$, the area would be $5^2 = 25~\text{cm}^2$ while the perimeter would be $4 \cdot 5 = 20~\text{cm}$. The diagonal will be calculated as $5\cdot \sqrt{2} = 7.071 ~\text{cm}$

In the following section, the algorithm, pseudocode and time-complexity of the program have also been covered.

## 1. Algorithm to calculate the area, perimeter and diagonal of a square

1. Take the length of side $s$ as input.

2. Declare $s^2$ as the area of the square

3. Declare $4s$ as the perimeter of the square

4. Declare $s\sqrt{2}$ as the diagonal of the square

## 2. Pseudocode to calculate the area, perimeter and diagonal of a square

Input : Length of side $s$

Output : Area $A$, Perimeter $P$ and Diagonal $D$ of the square

1. Procedure areaPerimeterDiagonal($s$):

2. $A = s^2$

3. $P = 4s$

4. $D = s\sqrt{2}$

5. Return $A, P, D$

6. End Procedure

## 3. Time complexity to calculate the area, perimeter and diagonal of a square

Time Complexity: O(1)

## 4. Java Program to calculate the area, perimeter and diagonal of a square

Code has been copied
/***********************************
alphabetacoder.com
Java program to calculate the area
,perimeter and diagonal of a square
************************************/

import java.util.Scanner;
import java.lang.Math;
import java.text.DecimalFormat;

class Main {
public static void main(String args[]) {
// declare instance of Scanner class
Scanner sc = new Scanner(System.in);

// declare instance of DecimalFormat class
DecimalFormat obj = new DecimalFormat("#.###");

// declare variables
double s, a, p, d;

// take input
System.out.print("Enter the length of side of the square: ");
s = sc.nextFloat();

// calculate area
a = s * s;
// calculate perimeter
p = 4 * s;
// calculate diagonal
d = s * Math.sqrt(2);

// display result upto 3 decimal places
System.out.println("Area: " + obj.format(a));
System.out.println("Perimeter: " + obj.format(p));
System.out.println("Diagonal: " + obj.format(d));
}
}


Output

Enter the length of side of the square: 25

Area: 625

Perimeter: 100

Diagonal: 35.355