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# Area of Triangle in Java

Updated on 19/07/20246,338 Views

## Introduction

Java is an object-oriented programming language developers widely use for developing software applications.

Java offers platform independence, vast libraries, and frameworks, making it a popular choice among developers, especially for building robust, scalable, and portable applications for web, enterprise, mobile, and embedded systems.

You can easily compute the area of triangle in Java. This could be done using formulas such as area = (base * height) / 2. For example, you can write a Java program that accepts user input for the base and height values and computes the triangle's area with these values' help.

## Overview

In this tutorial, we’ll discuss several methods of finding the area of a triangle in Java. Keep reading to know more.

## Formulas To Find the Area of a Triangle

### Using the base and height

If we know the base (b) and the height (h) of the triangle, we can use the formula:

Area = (b * h) / 2

### Using the lengths of three sides (Heron's formula)

If we know the lengths of all three sides (a, b, c), we can use Heron's formula:

Area = sqrt(s * (s - a) * (s - b) * (s - c))

where s = (a + b + c) / 2

### Using coordinates of vertices

If we know the coordinates of three vertices (x1, y1), (x2, y2), (x3, y3), we can use the shoelace formula:

Area = 0.5 * |(x1y2 + x2y3 + x3y1) - (x2y1 + x3y2 + x1y3)|

## Example 1 – Finding the Area of a Triangle in Java Using the Height and Base of the Triangle

Here is an example of calculating the area of a triangle using the height and base of the triangle (base x height) in Java:

`import java.util.Scanner;public class upGradTutorials {    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        System.out.println("Enter the base of the triangle:");        double base = scanner.nextDouble();        System.out.println("Enter the height of the triangle:");        double height = scanner.nextDouble();        double area = (base * height) / 2;        System.out.println("The area of the triangle is: " + area);    }}`

The program begins by importing the Scanner class from java.util package, allowing us to read user input. Next, a class named TriangleAreaCalculator is declared, which contains the main method, serving as the program's entry point.

Inside the main method, an instance of the Scanner class is created and associated with the standard input stream (System.in), enabling input reading. The program then prompts the user to enter the base of the triangle by printing the corresponding message. The entered value is read as a double using the nextDouble() method of the Scanner class and assigned to the base variable.

Similarly, the program prompts the user to enter the height of the triangle, reads the input value as a double, and assigns it to the height variable. The area of the triangle is calculated using the formula (base * height) / 2 and assigned to the area variable.

Finally, the program displays the calculated area of the triangle by printing the concatenation of the string "The area of the triangle is: " with the value of the area variable.

## Example 2 – Finding the Area of Triangle in Java Using the Three Sides of the Triangle

Here is an example of calculating the area of a triangle using the lengths of its three sides (Heron's formula) in Java:

`import java.util.Scanner;public class upGradTutorials {    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        System.out.println("Enter the length of side a:");        double a = scanner.nextDouble();        System.out.println("Enter the length of side b:");        double b = scanner.nextDouble();        System.out.println("Enter the length of side c:");        double c = scanner.nextDouble();        double s = (a + b + c) / 2;        double area = Math.sqrt(s * (s - a) * (s - b) * (s - c));        System.out.println("The area of the triangle is: " + area);    }}`

In the above example, the program prompts the user to enter the lengths of the triangle's three sides. It reads these values as double using the nextDouble() method of the Scanner class and assigns them to the variables a, b, and c.

Next, it calculates the semi-perimeter of the triangle (s) using the formula (a + b + c) / 2. Then, it applies Heron's formula to calculate the triangle area using the Math.sqrt() function to compute the square root.

Finally, the program displays the calculated area of the triangle by printing the concatenation of the string "The area of the triangle is: " with the value of the area variable.

## Example 3 - Finding the Area of a Triangle in Java Using Constructor

Here is an example of calculating the area of a triangle in Java using a constructor:

`import java.util.Scanner;public class Triangle {    private double base;    private double height;    private double area;    public Triangle (double base, double height) {        this.base = base;        this.height = height;    }    public void calculateArea() {        area = (base * height) / 2;    }    public double getArea() {        return area;    }    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        System.out.println("Enter the base of the triangle:");        double base = scanner.nextDouble();        System.out.println("Enter the height of the triangle:");        double height = scanner.nextDouble();        Triangle triangle = new Triangle(base, height);        triangle.calculateArea();        System.out.println("The area of the triangle is: " + triangle.getArea());    }}`

This example defines a Triangle class with private fields for base, height, and area. The class has a constructor that takes the base and height as parameters and assigns them to the corresponding fields.

We also have two methods within the Triangle class: calculateArea() and getArea(). The calculateArea() method calculates the area of the triangle using the formula (base * height) / 2 and stores the result in the area field. The getArea() method returns the value of the area field.

In the main method, we prompt the user to enter the base and height of the triangle and read those values using the Scanner class. Then, we create an instance of the Triangle class, passing the base and height as arguments to the constructor.

Next, we call the calculateArea() method on the triangle object to calculate the area. Finally, we display the calculated area of the triangle using the getArea() method. When the program runs, it asks the user to input the base and height of the triangle, creates a Triangle object, calculates the area using the provided values, and displays the resulting area of the triangle.

## Example 4 - Finding Area of Triangle in Java Using User-Defined Method

`import java.util.Scanner;public class upGradTutorials {    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        System.out.println("Enter the base of the triangle:");        double base = scanner.nextDouble();        System.out.println("Enter the height of the triangle:");        double height = scanner.nextDouble();        double area = calculateTriangleArea(base, height);        System.out.println("The area of the triangle is: " + area);    }    public static double calculateTriangleArea(double base, double height) {        return (base * height) / 2;    }}`

In this program, we define a class called TriangleAreaCalculator. The main method prompts the user to enter the base and height of the triangle, reads those values using the Scanner class, and assigns them to the variables base and height.

The program then calls the calculateTriangleArea method, passing the base and height as arguments. The calculateTriangleArea method calculates the triangle area using the formula (base * height) / 2 and returns the result.

Finally, the calculated area is stored in the area variable and displayed to the user using the System.out.println statement.

## Example 5 - Finding the Area of a Triangle in Java Using Object-Oriented Programming

Here is an example of calculating the area of a triangle in Java using object-oriented programming:

`import java.util.Scanner;public class Triangle {    private double sideA;    private double sideB;    private double sideC;    public Triangle(double a, double b, double c) {        sideA = a;        sideB = b;        sideC = c;    }    public double calculateArea() {        double s = (sideA + sideB + sideC) / 2;        return Math.sqrt(s * (s - sideA) * (s - sideB) * (s - sideC));    }    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        System.out.println("Enter the length of side A:");        double sideA = scanner.nextDouble();        System.out.println("Enter the length of side B:");        double sideB = scanner.nextDouble();        System.out.println("Enter the length of side C:");        double sideC = scanner.nextDouble();        Triangle triangle = new Triangle(sideA, sideB, sideC);        double area = triangle.calculateArea();        System.out.println("The area of the triangle is: " + area);    }}`

In the above program, we define a Triangle class representing a triangle object. The Triangle class has private fields for sideA, sideB, and sideC, representing the lengths of the triangle's three sides.

The Triangle class has a constructor that takes sideA, sideB, and sideC as parameters and initializes the corresponding fields.

Additionally, the Triangle class has a calculateArea() method that calculates the area of the triangle using Heron's formula: Math.sqrt(s * (s - sideA) * (s - sideB) * (s - sideC)), where s is the semi-perimeter of the triangle.

In the main method, we prompt the user to enter the lengths of the triangle's sides (sideA, sideB, and sideC) and read those values using the Scanner class. We then create a Triangle object by invoking the constructor with the provided side lengths.

Next, we call the calculateArea() method on the triangle object to calculate the area and store the result in the area variable. Finally, we display the calculated area of the triangle using the System.out.println statement.

## Conclusion

The numerous ways of calculating the area of a triangle in Java have been discussed in this tutorial. You must enroll in a certified course if you want to use Java for more advanced functions. You could look for software development courses by upGrad. The courses on upGrad are well-designed for professionals and ensure you develop a holistic understanding of the subject. Enquire today to know more.

## FAQs

1. What data types should I use for the base and height values?

The base and height values can be represented using the double data type in Java, which can be decimal numbers.

1. What is the constructor of the area of a triangle in Java?

In Java, the constructor of the area of a triangle would typically be defined within a Triangle class and would take the base and height values as parameters. It would initialize the instance variables of the Triangle object with the provided values.

1. Can I use the Math class in Java to calculate the area of a triangle?

The Math class in Java provides various mathematical functions. However, you cannot use it directly to calculate a triangle's area. You will need to implement the formula manually.

Director of Engineering

Director of Engineering @ upGrad. Motivated to leverage technology to solve problems. Seasoned leader for startups and fast moving orgs. Working …Read More

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