Solution

src/main/java/koz01/java2/lab05/Point.java

 package koz01.java2.lab05;
 
+import lombok.ToString;
+
+@ToString
 public class Point {
 
+
+	public static Point getRandomPointWithDistanceFromOrigin(double distance) {
+		if (distance < 0) {
+			throw new IllegalArgumentException("distance = " + distance +
+				" is negative");
+		}
+		// x = distance * cos(phi)
+		// y = distance * sin(phi)
+		double phi = Math.random() * 2 * Math.PI;
+		return new Point(distance * Math.cos(phi), distance * Math.sin(phi));
+	}
+
 	private double x;
 	
 	private double y;
@@ -23,5 +38,23 @@ public class Point {
 	protected boolean canEqual(Point point) {
 		return true;
 	}
-	
+
+	/**
+	 * Naimplementujte hashCode pomocí vzorce resultHashCode := resultHashCode*31
+	 * + hashCode(attribute).
+	 */
+	@Override
+	public int hashCode() {
+		int resultHashCode = 1;
+		resultHashCode = resultHashCode * 31 + Double.hashCode(x);
+		resultHashCode = resultHashCode * 31 + Double.hashCode(y);
+		return resultHashCode;
+	}
+
+	public double distance(Point p) {
+		double dY = p.y - this.y;
+		double dX = p.x - this.x;
+		return Math.sqrt(dY * dY + dX * dX);
+	}
+
 }

src/test/java/koz01/java2/lab05/ExampleTest.java

+package koz01.java2.lab05;
+
+import org.junit.jupiter.api.Test;
+
+public class ExampleTest {
+
+	@Test
+	public void testFoo() {
+
+	}
+}

src/test/java/koz01/java2/lab05/TestPoint.java

+package koz01.java2.lab05;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+import lombok.extern.log4j.Log4j2;
+
+@Log4j2
+public class TestPoint {
+
+	@Test
+	public void testHashCode() {
+		Set<Point> testingSet = new HashSet<>();
+		Point p1 = new Point(10, 12);
+		testingSet.add(p1);
+		
+		log.info("contains = {} ", testingSet.contains(p1));
+		log.info("p1.hashCode = {} ", p1.hashCode());
+		assertTrue(testingSet.contains(p1));
+
+		Point p2 = new Point(10, 12);
+		assertEquals(p1, p2);
+		log.info("p2.hashCode = {} ", p2.hashCode());
+		assertTrue(testingSet.contains(p2));
+	}
+
+	@Test
+	public void testPerformance() {
+		long start = System.currentTimeMillis();
+		Set<Point> points = new HashSet<>();
+		for (int i = 0; i < 100000; i++) {
+			points.add(new Point(i, i));
+		}
+
+
+
+		points.contains(new Point(0, 0));
+		long end = System.currentTimeMillis();
+		log.info("duration = {} ms", end - start);
+	}
+
+	@Test
+	public void testNegativeDistance() {
+		assertThrows(IllegalArgumentException.class, () -> {
+			Point.getRandomPointWithDistanceFromOrigin(-10);
+		});
+	}
+
+	@Test
+	public void testGenerate() {
+		Point p = Point.getRandomPointWithDistanceFromOrigin(1000.);
+		assertEquals(1000., p.distance(new Point(0, 0)));
+		log.info("point = {}", p);
+	}
+}