Simple CSV Parser for Java

buddies.csv

CSV.java

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Supplier;

public class CSV {
    private static String COMMA_DELIMITER = ",";

    private Map<String, List<String>> properties;
    private int count;

    private CSV() {
        properties = new LinkedHashMap<>();
        count = 0;
    }

    public List<?> as(Supplier<?> constructor) throws IndexOutOfBoundsException,
        IllegalAccessException, IllegalArgumentException {
        var instances = new ArrayList<>();
        for (var index = 0; index < count; index++) {
            var instance = constructor.get();
            var clazz = instance.getClass();
            var fields = clazz.getDeclaredFields();
            for (var field : fields) {
                field.setAccessible(true);
                var type = field.getType();
                for (var property : properties.keySet()) {
                    if (property.equalsIgnoreCase(field.getName())) {
                        var value = properties.get(property).get(index);
                        try {
                            field.set(instance, type.cast(value));
                        } catch (ClassCastException e) {
                            if (type.equals(java.time.LocalDate.class)) {
                                // TODO: cast value from java.lang.String to java.time.LocalDate
                                // field.set(instance, java.time.LocalDate.parse(value));
                            }
                        }
                    }
                }
            }
            instances.add(instance);
        }
        return instances;
    }

    public static CSV from(String filePath) throws IOException, IndexOutOfBoundsException {
        var csv = new CSV();
        try (var reader = new BufferedReader(new FileReader(filePath))) {
            String firstLine = reader.readLine();
            for (var word : firstLine.split(COMMA_DELIMITER)) {
                csv.properties.put(
                    word.toString().trim().toLowerCase(),
                    new ArrayList<String>());
            }
            String line;
            var properties = csv.properties.keySet();
            while ((line = reader.readLine()) != null) {
                var values = line.split(COMMA_DELIMITER);
                var currentIndex = 0;
                for (var property : properties) {
                    csv.properties.get(property)
                        .add(values[currentIndex++].trim());
                }
                csv.count++;
            }
        } catch (FileNotFoundException e) {
            throw e;
        }
        return csv;
    }
}

Test.java

public class Test {
    public static void main(String[] args) throws Exception {
        var buddies = CSV.from("buddies.csv").as(Buddy::new);
        buddies.forEach(buddy -> {
            System.out.println(((Buddy)buddy).getFullName());
            System.out.println(((Buddy)buddy).getEmail());
            System.out.println(((Buddy)buddy).getPhoneNumber());
            System.out.println(((Buddy)buddy).getBirthday());
            System.out.println("---");
        });
    }
}

class Buddy {
    private static String SPACE_DELIMITER = " ";

    private String firstName;
    private String lastName;
    private String email;
    private String phoneNumber;
    private java.time.LocalDate birthday;

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public String getFullName() {
        return firstName + SPACE_DELIMITER + lastName;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getEmail() {
        return email;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setBirthday(java.time.LocalDate birthday) {
        this.birthday = birthday;
    }

    public java.time.LocalDate getBirthday() {
        return birthday;
    }
}