The challenge
Write a simple function that takes polar coordinates (an angle in degrees and a radius) and returns the equivalent cartesian coordinates (rounded to 10 places).
For example:
coordinates(90,1) => (0.0, 1.0)
coordinates(45, 1) => (0.7071067812, 0.7071067812)
The solution in Java code
Option 1:
import java.awt.geom.Point2D;
class CoordinatesInspector {
Point2D.Double coordinates(Double degrees, Double radius) {
return new Point2D.Double(
Math.round(radius * Math.cos(Math.toRadians(degrees)) * 10e9) / 10e9,
Math.round(radius * Math.sin(Math.toRadians(degrees)) * 10e9) / 10e9);
}
}
Option 2:
import java.awt.geom.Point2D;
import java.math.*;
public class CoordinatesInspector {
public Point2D coordinates(Double degrees, Double radius) {
double rd = Math.toRadians(degrees);
double x = radius * Math.cos(rd);
double y = radius * Math.sin(rd);
BigDecimal xb = new BigDecimal(x).setScale(10, RoundingMode.HALF_UP);
BigDecimal yb = new BigDecimal(y).setScale(10, RoundingMode.HALF_UP);
return new Point2D.Double(xb.doubleValue(),yb.doubleValue());
}
}
Option 3:
import java.awt.geom.Point2D;
public class CoordinatesInspector {
public static Point2D coordinates(Double degrees, Double radius) {
var radians = Math.toRadians(degrees);
return new Point2D.Double(
Double.parseDouble(String.format("%.10f", radius * Math.cos(radians))),
Double.parseDouble(String.format("%.10f", radius * Math.sin(radians)))
);
}
}
Test cases to validate our solution
import java.awt.geom.Point2D;
import org.junit.Test;
import static org.junit.Assert.assertEquals;
public class CoordinatesTest {
@Test public void test_1() {
Point2D result = new CoordinatesInspector().coordinates(90.0,1.0);
assertEquals("Incorrect coordinates", new Point2D.Double(0.0,1.0), result);
}
}
Additional test cases
import java.awt.geom.Point2D;
import static org.junit.Assert.*;
import org.junit.Test;
public class CoordinatesTest {
@Test public void test_1() {
Point2D result = new CoordinatesInspector().coordinates(90.0,1.0);
assertEquals("Incorrect coordinates", new Point2D.Double(0.0,1.0), result);
}
@Test public void test_2() {
Point2D result = new CoordinatesInspector().coordinates(90.0,2.0);
assertEquals("Incorrect coordinates", new Point2D.Double(0.0,2.0), result);
}
@Test public void test_3() {
Point2D result = new CoordinatesInspector().coordinates(0.0,1.0);
assertEquals("Incorrect coordinates", new Point2D.Double(1.0,0.0), result);
}
@Test public void test_4() {
Point2D result = new CoordinatesInspector().coordinates(45.0,1.0);
assertEquals("Incorrect coordinates", new Point2D.Double(0.7071067812,0.7071067812), result);
}
@Test public void test_5() {
Point2D result = new CoordinatesInspector().coordinates(1090.0,10000.0);
assertEquals("Incorrect coordinates", new Point2D.Double(9848.0775301221,1736.4817766693), result);
}
@Test public void test_6() {
Point2D result = new CoordinatesInspector().coordinates(-270.0,1.0);
assertEquals("Incorrect coordinates", new Point2D.Double(0.0,1.0), result);
}
}
