In this post, we feature a comprehensive article about math.pi java.
1. Introduction
PI is a mathematics number defined as the circumference of any circle divided by its diameter. Java has provided the java.lang.Math class since version 1. It includes static constant math.pi java with the value of 3.141592653589793.
/*the double value that is closer than any other to pi, the ratio of the circumference of a circle to its diameter.*/ static double PI = 3.141592653589793;
In this example, I will print out the math.pi java value and use it to calculate a circle’s circumference and area.
2. Technologies Used
The example code in this article was built and run using:
- Java 11
- Maven 3.3.9
- Eclipse Oxygen
- Junit 4.12
3. Maven Project
3.1 Dependencies
I will include Junit in the pom.xml.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>jcg.zheng.demo</groupId> <artifactId>java-pi-demo</artifactId> <version>0.0.1-SNAPSHOT</version> <build> <sourceDirectory>src</sourceDirectory> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.0</version> <configuration> <release>11</release> </configuration> </plugin> </plugins> </build> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> </dependency> </dependencies> </project>
3.2 Circle
In this step, I will create a Circle class which has a diameter data member and two methods:
calculateCircumference()– calculate a circle’s circumference by multiplying PI by its diameter.calculateArea() – calculate a circle’s area by multiplying PI by the square of its radius.
Circle.java
package jcg.zheng.demo;
public class Circle {
public Circle(double diameter) {
super();
this.diameter = diameter;
}
private double diameter;
public double calculateCircumference() {
return Math.PI * diameter;
}
public double calculateArea() {
return Math.PI * Math.pow(diameter / 2, 2);
}
}
3.3. Circle Test
In this step, I will create a CircleTest class to print out Math.PI value and calculate a circle’s circumference and area.
print_Pi_value()– prints outMath.PIvalue.calculateCircumference()– calculates the circumference of a circle whose diameter is 10 units.calculateArea()– calculates the area of a circle whose diameter is 20 units.
CircleTest.java
package jcg.zheng.demo;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class CircleTest {
@Test
public void print_Pi_value() {
System.out.println(Math.PI);
System.out.printf("%.16f", Math.PI);
assertEquals(3.14, Math.PI, 2);
}
@Test
public void calculateCircumference() {
double diameter = 10;
Circle c = new Circle(diameter);
assertEquals(31.42, c.calculateCircumference(), 2);
}
@Test
public void calculateArea() {
double diameter = 20;
Circle c = new Circle(diameter);
assertEquals(314.23, c.calculateArea(), 2);
}
}
Execute mvn test -Dtest=CircleTest and capture output here.
Output
------------------------------------------------------- T E S T S ------------------------------------------------------- Running jcg.zheng.demo.CircleTest 3.141592653589793 3.1415926535897930 Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.126 sec Results : Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
Note: Math.PI value is defined as 3.141592653589793.
4. Summary
PI is a mathematics number defined as the circumference of any circle divided by its diameter. In this example, I demonstrate through examples the Math.PI value and how to use it to calculate a circle’s circumference and area.
5. More articles
6. Download the Source Code
This example consists of a Maven project which demonstrates the Math.PI constant.
You can download the full source code of this example here: Pi in Java Example
Last updated on Jun. 15th, 2021
Oh, I thought you were going to calculate PI, not just use it. Useful post though, nevertheless.