Creating objects via Builder from csv file using a stream

Question

I would like to create a "Planet" object from a .csv file using a PlanetBuilder and stream. I've only gotten so far that I can read the csv file and for each line, create a Planet object, but unfortunately i do not know how to assign the constructor values to the object, so it basically just creates an empty planet object for each line. Could someone please tell me how to also assign the value for each lines?

After creating the objects I will add them to List planets

This is the method which creates a new planet object.

public List<Planet> csvDataToPlanets(String filePath) {
    List<Planet> planets = new ArrayList<>();
    try (Stream<String> lines = Files.lines(Paths.get(filePath))) {
        List<List<String>> places = lines.skip(1).map(line -> Arrays.asList(line.split(","))).collect(Collectors.toList());
        places.forEach(place -> new PlanetBuilder().createPlanet());
    } catch (IOException e) {
        e.printStackTrace();
    }
    return planets;
}

This is the CSV file.

planet_name,inhabitants,has_stargate,has_dhd,teams_visited
Abydos,0,True,False,[sg-1]
Adara II,117778380,True,True,[sg-1]
Adora,0,False,False,[sg-1]
Alaris,13663,True,True,[sg-1]
Alebran's planet,186402846,False,False,[sg-1; sg-6]
Alpha Site,460849025,True,True,[sg-1; sg-4]
Altair,8087,False,False,[sg-1; sg-2]
Amon Shek,0,True,True,[sg-1; sg-9]
Amra,467925616,True,False,[sg-1]
Apophis's training camp,10188,True,True,[sg-1]
Ardena,13693,True,True,[sg-1; sg-5]
Argos,0,True,True,[sg-1]
Arkad's planet,257318689,True,False,[sg-1; sg-14]
Arkhan's planet,464136466,False,False,[sg-1]

As well as my Planet class and Planetbuilder class

public class Planet {
private String name;
private long inhabitants;
private boolean stargateAvailable;
private boolean dhdAvailable;
private List<String> teamsVisited;


public Planet(String name, long inhabitants, boolean stargateAvailable, boolean dhdAvailable, List<String> teamsVisited) {
}

public String getName() {
    return name;
}

public long getInhabitants() {
    return inhabitants;
}

public boolean isStargateAvailable() {
    return stargateAvailable;
}

public boolean isDhdAvailable() {
    return dhdAvailable;
}

public List<String> getTeamsVisited() {
    return teamsVisited;
}

@Override
public String toString() {
    return name;
}


public class PlanetBuilder {
private String name;
private long inhabitants;
private boolean stargateAvailable;
private boolean dhdAvailable;
private List<String> teamsVisited;

public PlanetBuilder Name(String name) {
    this.name = name;
    return this;
}

public PlanetBuilder Inhabitants(long inhabitants) {
    this.inhabitants = inhabitants;
    return this;
}

public PlanetBuilder StargateAvailable(boolean stargateAvailable) {
    this.stargateAvailable = stargateAvailable;
    return this;
}

public PlanetBuilder DhdAvailable(boolean dhdAvailable) {
    this.dhdAvailable = dhdAvailable;
    return this;
}

public PlanetBuilder TeamsVisited(List<String> teamsVisited) {
    this.teamsVisited = teamsVisited;
    return this;
}

public Planet createPlanet() {
    return new Planet(name, inhabitants, stargateAvailable, dhdAvailable, teamsVisited);
}

stephendnicholas · Accepted Answer · 2018-04-18 11:36:20Z

1

The simplest answer is for you to expand the logic inside your places.forEach(place ->...) call, so that you take each value from the place (which is a List<String> of the values) and add calls on your builder for each property (parsing them as necessary). E.g. places.forEach(place -> new PlanetBuilder().Name(place.get(0)).createPlanet()); (no parsing needed in this case)

However this is definitely not the nicest solution.

Ideally you'd move to using a library like http://beanio.org/ or http://flatworm.sourceforge.net/ to take care of the unmarshalling for you.

answered Apr 18, 2018 at 11:36

stephendnicholas

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1 Comment

NewishToProgramming Over a year ago

Wow, ive been stuck here for 3 days, thank you very much.

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