How to implement Train class

Question

I have the following two classes:

public class Station{

    private String id;
    
    private String description;
    
    private boolean isTerminus;
    
    private int numberPassengersInTransit;
    
    public Station(String id, String desc) {
        this.id = id;
        description= desc;
    }

    public String getDescription() {
        return descrizione;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public boolean isTerminus() {
        return isTerminus;
    }

    public void setTerminus(boolean isTerminus) {
        this.isTerminus = isTerminus;
    }

    public String getId() {
        return id;
    }
    
    public int getNumberPassengersInTransit() {
        return numberPassengersInTransit;
    }
    
    public void addPassenger() {
        numberPassengersInTransit++;
    }
    
    public void addGroupPassengers(int num) {
        numberPassengersInTransit += num;
    }
}

and

public class Train {

    
    private String id;
    
    private String description;
        
    private Station parkingPlace;
        
    private int numberPassengersOnBoard;
    
    public final int NUMBER_MAX_PASSENGERS = 200; 
        
    private StringBuilder log = new StringBuilder();

    public Train(String id, String desc, Station parkingPlace) {
        this.id = id;
        descrizione = desc;
        this.parkingPlace = parkingPlace;
    }

    public Station getParkingPlace() {
        return parkingPlace;
    }

    public void setParkingPlace(Station parkingPlace) {
        this.parkingPlace = parkingPlace;
    }
    
    public int getNumberPassengersOnBoard() {
        return numberPassengersOnBoard;
    }

    public String getId() {
        return id;
    }

    public String getDescription() {
        return description;
    }

    public void runs(Station arrival) {
        
        log.append("The train "+id+" travel to the station "+parkingPlace.getDescription()+" at the station "+arrival.getDescription()+".");
        parkingPlace=arrival;
    }

    public void addPassenger() {
        
        if(numberPassengersOnBoard<NUMBER_MAX_PASSENGERS)
            numberPassengersOnBoard++;
        else
            System.out.println("Error");
    }
    
    public void addGroupPassengers(int num) {
        
        if(numberPassengersOnBoard+num<NUMBER_MAX_PASSENGERS)
            numberPassengersOnBoard++;
        else
            System.out.println("Error");
        
    }
    
    public String getLog() {
        return log.toString();
    }
    

}

The test classes:

import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;

public class StationTest {
    
    private Station sta;
    
    @Before
    public void setUp() throws Exception {
        sta = new Station("STRM0001","Giardinetti");
    }

    @Test
    public void testConstructorStation() {
        assertEquals("The station id was not initialized correctly", 
                "STRM0001", sta.getId());
        assertEquals("The description from the station was not initialized correctly", 
                "Giardinetti", sta.getDescription());
        assertEquals("At creation the number of passengers in transit is 0.", 
                0, sta.getNumberPassengersInTransit());
    }

    @Test
    public void testAddPassenger() {
        sta.addPassenger();
        assertEquals("After adding a passenger for the first time, the number of passengers in transit must be 1.", 
                1, sta.getNumberPassengersInTransit());
    }
    
    @Test
    public void testAddGroupPassengers() {
        sta.addGroupPassengers(5);
        assertEquals("After adding a group of passengers for the first time, the number of passengers in transit must be consistent.", 
                5, sta.getNumberPassengersInTransit());
    }

    @Test
    public void testAddPassengerAndThenGroupPassengers() {
        sta.addPassenger();
        sta.addGroupPassengers(3);
        assertEquals("After adding a passenger and then a group of passengers" +
        " the number of passengers in transit must be consistent.", 
                4, sta.getNumberPassengersInTransit());
    }
    
    @Test
    public void testAggiungiGruppoPasseggeriEPoiPasseggero() {
        sta.addGroupPassengers(2);
        sta.addPassenger();
        assertEquals("After adding a passenger and then a group of passengers" +
        " the number of passengers in transit must be consistent.", 
                3, sta.getNumberPassengersInTransit());
    }
}




import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;

public class TrenoTest {
    
    private Train trainTest;
    private Station stationTest;
    
    @Before
    public void setUp() throws Exception {
        trainTest = new Train("testRM001", "Yellow arrow", stationTest);
    }

    @Test
    public void testConstructorTrain() {
        assertEquals("L'id from the train was not initialized correctly", 
                "testRM001", trainTest.getId());
        assertEquals("The description from the train was not initialized correctly", 
                "Yellow arrow", trainTest.getDescription());
        assertEquals("The train station was not initialized correctly. ", 
                stationTest, trainTest.getParkingPlace());
    }

    @Test
    public void testRuns() {
        Station st1 = new Station("STRM0001","Giardinetti");
        trainTest.setParkingPlace(st1);
        Station st2 = new Station("STRM0002","Termini");
        assertEquals("The departure station does not coincide with the train station.", 
                st1, trainTest.getParkingPlace());
        trenoTest.effettuaCorsa(st2);
        assertEquals("The arrival station does not coincide with the train station.", 
                st2, trainTest.getParkingPlace());
        String log = "The testRM001 train travels from Giardinetti station to Termini station.";
        assertEquals("The log does not report correct information.", log, trainTest.getLog());
    }
    
    @Test
    public void testAddPassenger() {
        trainTest.addPassenger();
        assertEquals("After adding a passenger for the first time, the number of passengers in transit must be 1.", 
                1, trainTest.getNumberPassengersOnBoard());
    }
    
    @Test
    public void testAddGroupPassengers() {
        trainTest.addGroupPassengers(5);
        assertEquals("After adding a group of passengers for the first time, the number of passengers in transit must be consistent.", 
                5, trainTest.getNumberPassengersOnBoard());
    }

    @Test
    public void testAddPassengerAndThenGroupPassengers() {
        trainTest.addPassenger();
        trainTest.addGroupPassengers(3);
        assertEquals("After adding a passenger and then a group of passengers" +
        " the number of passengers in transit must be consistent.", 
                4, trainTest.getNumberPassengersOnBoard());
    }
    
    @Test
    public void testAddGroupPassengersAndThenPassenger() {
        trainTest.addGroupPassengers(2);
        trainTest.addPassenger();
        assertEquals("After adding a passenger and then a group of passengers " +
        " the number of passengers in transit must be consistent.", 
                3, trainTest.getNumberPassengersOnBoard());
    }
}

Running the two classes I get the following errors:

After adding a passenger and then a group of passengers, the number of passengers in transit must be consistent. expected: <3> but was: <2>.
After adding a group of passengers for the first time, the number of passengers in transit must be consistent. expected: <5> but was: <1>.
After adding a passenger and then a group of passengers, the number of passengers in transit must be consistent. expected: <4> but was: <2>.

How can I fix the three errors above?

Debug your code! Start with why doesn't `addGroupPassengers()` use the `num` parameter ? — John3136, Jan 03 '21 at 06:38
*"How can I fix the three errors above?"* - Have you tried using your IDE's debugger? Have you tried the [Rubber Duck debugging technique](https://rubberduckdebugging.com/)? They will allow you to identify the reasons for the test failures. Fixing them is then (probably) just a matter of thinking about it. — Stephen C, Jan 03 '21 at 06:40
You might want to check https://stackoverflow.com/questions/25385173/what-is-a-debugger-and-how-can-it-help-me-diagnose-problems on how to use a debugger. — Progman, Jan 03 '21 at 11:41

score 1 · Answer 1 · answered Jan 03 '21 at 07:17

public void addGroupPassengers(int num) {
    
    if(numberPassengersOnBoard+num<NUMBER_MAX_PASSENGERS)
        numberPassengersOnBoard++;
    else
        System.out.println("Error");
    
}

This part says that if the current number of passengers + the number of people in the group you want to add are < MAX number of passengers, then you add ONLY ONE passenger to the current one. Changing it into this should make it work.

public void addGroupPassengers(int num) {

    if(numberPassengersOnBoard+num<NUMBER_MAX_PASSENGERS)
        numberPassengersOnBoard+= num;
    else
        System.out.println("Error");

}

How to implement Train class

1 Answers1