# How to calculate Area of Triangle through a Java program ?.

Updated on September 17, 2014

## Introduction

In this tutorial you will learn how to calculate Area of Triangle through a Java program. In order to calculate area of triangle you need two things. One is base of the triangle and other is height of triangle. Formula for calculating Area of Triangle is - (height * base) / 2. In order to get value for height and base of triangle, we use Scanner class in Java and prompt the user to enter value on the console.

## Java source code - How to calculate Area of Triangle.

```// Step 1 - Import all the necessary classes from Java
// API which helps us in calculating Area of Triangle.
// Here, we are using Scanner class present in java.util package.
import java.util.Scanner;

// Step 2 - Create a Java class which will have code to calculate
// Area of Triangle. The class created in this tutorial is named as
// AreaOfTriangle.
public class AreaOfTriangle {

// Step 3 - Create a main method in class AreaOfTriangle. This
// method has a signature as public static void main(String [] args).
// The method with this signature is been called by the JVM, whenever
// we run a Java program. This method is the starting point of execution
// of our Java code to calculate Area of triangle.
public static void main(String[] args) {

// Step 4 - Create a Scanner instance. The constructor used will have a
// parameter of System.in instance. System.in provide Scanner
// capability of reading user input from console.
Scanner scanner = new Scanner(System.in);

// Step 5 - In order to calculate Area of triangle, base of triangle is required.
// Prompt the user to enter value of base of the triangle.
System.out.print("Enter value of base of Triangle : ");

// Step 6 - User enters base of Triangle on the console and it is been read
// by scanner object by the method nextDouble() and return value
// is been stored in the base variable. This base variable is of type double.
double base = scanner.nextDouble();

// Step 7 - In order to calculate Area of triangle, height of triangle is required.
// Prompt the user to enter value of height of the triangle.
System.out.print("Enter value of base of Triangle : ");

// Step 8 - User enters height of Triangle on the console and it is been read
// by scanner object by the method nextDouble() and return value
// is been stored in the height variable. This height variable is of type double.
double height = scanner.nextDouble();

// Step 9 - In order to store Area of Triangle in a variable, we will create a
// variable by name area. The area variable will be of type double. Lets assign
// value 0 to area variable.
double area = 0;

System.out.println("Calculating Area of Triangle - ");

// Step 10 - Formula for calculating Area of Triangle is as follows :
// Area of Triangle = 1 / 2 * ( height * base ). The area is calculated
// and stored in the area variable created above in step 9.
area = (height * base) / 2 ;

// Step 11 - Output displayed on the console -

System.out.println("The Area of Triangle is - " + area);
}

}
```

## Steps to implement -

Step 1 - Import all the necessary classes from Java API which helps us in calculating Area of Triangle. Here, we are using Scanner class present in java.util package.

Step 2 - Create a Java class which will have code to calculate Area of Triangle. The class created in this tutorial is named as AreaOfTriangle.

Step 3 - Create a main method in class AreaOfTriangle. This method has a signature as public static void main(String [ ] args). The method with this signature is been called by the JVM, whenever we run a Java program. This method is the starting point of execution of our Java code to calculate Area of triangle.

Step 4 - Create a Scanner instance. The constructor used will have a parameter of System.in instance. System.in provide Scanner capability of reading user input from console.

Step 5 - In order to calculate Area of triangle, base of triangle is required. Prompt the user to enter value of base of the triangle.

Step 6 - User enters base of Triangle on the console and it is been read by scanner object by the method nextDouble() and return value is been stored in the base variable. This base variable is of type double.

Step 7 - In order to calculate Area of triangle, height of triangle is required. Prompt the user to enter value of height of the triangle.

Step 8 - User enters height of Triangle on the console and it is been read by scanner object by the method nextDouble() and return value is been stored in the height variable. This height variable is of type double.

Step 9 - In order to store Area of Triangle in a variable, we will create a variable by name area. The area variable will be of type double. Lets assign value 0 to area variable.

Step 10 - Formula for calculating Area of Triangle is as follows :

Area of Triangle = 1 / 2 * ( height * base ). The area is calculated and stored in the area variable created above in step 9.

## Output of the program - Explanation

On running main method of class AreaOfTriangle, it prompts user to enter base of Triangle. On providing base of Triangle when user hits enter key, it prompts again to enter value of height of Triangle. After providing height of Triangle when user hits enter key, Area of Triangle is calculated by the formula height * base / 2. It than simply displays Area of Triangle on the console.

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