vincentius15

import org.junit.Test;

import static org.junit.Assert.*;

public class MovingObjectTest {
    @Test
    public void testDisplacement(){
        MovingObject object = new MovingObject(10, 10, 10, 10);
        assertEquals(600, object.displacement(), 0);
    }

vincentius15

public class Square {
    public int topLeftCoordinateX;
    public int topLeftCoordinateY;
    public int side;
}

public class AreaCalculator{
    public double area(Object shape){
        if (shape instanceof Square){
            Square square = (Square) shape;

vincentius15

public interface Shape{
    double area();
}

public class Square {
    private int topLeftCoordinateX;
    private int topLeftCoordinateY;
    private int side;
    
    public double area(){