Week 7: Enum, Generic Type, Streams, write to file, class diagram/03. Routes in the Given Direction

The program has defined the Route class written in the previous exercise.

Write a method:

public static ArrayList<Route> routesInDirection(ArrayList<Route> routes, CardinalDirection direction)
which receives a list of route objects and a direction as parameters.


The method returns a new list containing those routes that go in the given direction.
The ORDER of the routes in the new list should be the SAME as in the list provided as a parameter.




import java.util.ArrayList;
import java.util.Random;

public class Test{
    public static void main(String[] args){
        final Random r = new Random();
        
   
        ArrayList<Route> al = new ArrayList<>();
        int count = r.nextInt(5) + 10;
        
        for (int i = 0; i < count; i++) {
            double length = r.nextInt(200) + 10;
            CardinalDirection direction = CardinalDirection.values()[r.nextInt(4)];
            al.add(new Route(length, direction));
        }
        
        System.out.println("All routes:");
        al.stream().forEach(rt -> System.out.println("" + rt));

        for (CardinalDirection direction : CardinalDirection.values()) {
            System.out.println("");
            System.out.println("Routes in the direction " + direction);
            
            ArrayList<Route> al2 = routesInDirection(al, direction);
            al2.stream().forEach(rt -> System.out.println("" + rt));
        }        
    }



    //add
    public static ArrayList<Route> routesInDirection(ArrayList<Route> routes, CardinalDirection direction) {
        // initialise empty ArrayList
        // approach 1 - works
        ArrayList<Route> filteredRoutes = new ArrayList<Route>();
        // approach 2 - works
        // in Java 7+
        // ArrayList<Route> filteredRoutes = new ArrayList<>();
        
        for (Route route: routes) {
            if (route.getDirection() == direction) {
                filteredRoutes.add(route);
            }
        }
        return filteredRoutes;
    }









}






All routes:
Direction: NORTH, length: 125.0
Direction: WEST, length: 160.0
Direction: NORTH, length: 114.0
Direction: NORTH, length: 196.0
Direction: NORTH, length: 167.0
Direction: NORTH, length: 169.0
Direction: WEST, length: 120.0
Direction: EAST, length: 124.0
Direction: WEST, length: 34.0
Direction: NORTH, length: 173.0
Direction: EAST, length: 107.0
Direction: WEST, length: 167.0
Direction: NORTH, length: 95.0

Routes in the direction NORTH
Direction: NORTH, length: 125.0
Direction: NORTH, length: 114.0
Direction: NORTH, length: 196.0
Direction: NORTH, length: 167.0
Direction: NORTH, length: 169.0
Direction: NORTH, length: 173.0
Direction: NORTH, length: 95.0

Routes in the direction SOUTH

Routes in the direction EAST
Direction: EAST, length: 124.0
Direction: EAST, length: 107.0

Routes in the direction WEST
Direction: WEST, length: 160.0
Direction: WEST, length: 120.0
Direction: WEST, length: 34.0
Direction: WEST, length: 167.0