Load every class from config using fieldnames

ConfigLoader.java

/**
 * @author <a href="https://github.com/Yuhtin">Yuhtin</a>
 */

import org.bukkit.configuration.ConfigurationSection;
import org.bukkit.configuration.file.FileConfiguration;
import org.bukkit.configuration.file.YamlConfiguration;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class ConfigLoader {
    private final File file;
    private final String sectionName;

    public ConfigLoader(File file, String sectionName) {
        this.file = file;
        this.sectionName = sectionName;
    }

    public <T> List<T> load(Class<T> clazz) {
        List<T> list = new ArrayList<>();
        FileConfiguration config = YamlConfiguration.loadConfiguration(file);

        if (config.isConfigurationSection(sectionName)) {
            ConfigurationSection section = config.getConfigurationSection(sectionName);

            for (String key : section.getKeys(false)) {
                Map<String, Object> map = section.getConfigurationSection(key).getValues(false);
                try {
                    T instance = clazz.newInstance();
                    for (Map.Entry<String, Object> entry : map.entrySet()) {
                        String fieldName = entry.getKey();
                        Object fieldValue = entry.getValue();
                        setField(instance, clazz, fieldName, fieldValue);
                    }
                    list.add(instance);
                } catch (InstantiationException | IllegalAccessException e) {
                    e.printStackTrace();
                }
            }
        }

        return list;
    }

    private <T> void setField(T instance, Class<T> clazz, String fieldName, Object fieldValue) {
        try {
            clazz.getDeclaredField(fieldName).set(instance, fieldValue);
        } catch (NoSuchFieldException | IllegalAccessException e) {
            e.printStackTrace();
        }
    }
}

ConfigLoaderTest.java

import org.junit.Test;

import java.io.File;
import java.util.List;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

public class ConfigLoaderTest {
    
    @Test
    public void testLoadRodFromConfig() {
        File configFile = new File("rods.yml");
        ConfigLoader configLoader = new ConfigLoader(configFile, "rod");

        List<Rod> rodList = configLoader.load(Rod.class);

        assertNotNull(rodList);
        assertEquals(5, rodList.size());
        assertEquals(1, rodList.get(0).getId());
        assertEquals("de Bambú", rodList.get(0).getName());
        assertEquals(10.0, rodList.get(0).getMaxWeight(), 0.001);
        assertEquals(0, rodList.get(0).getPrice(), 0.001);
        assertEquals(5, rodList.get(4).getId());
        assertEquals("Telescópica", rodList.get(4).getName());
        assertEquals(250.0, rodList.get(4).getMaxWeight(), 0.001);
        assertEquals(72500000, rodList.get(4).getPrice(), 0.001);
    }
}

Rod.java

import lombok.Builder;
import lombok.Data;

/**
 * @author <a href="https://github.com/Yuhtin">Yuhtin</a>
 */
@Builder
@Data
public class Rod {

    private final int id;
    private final String name;
    private final double maxWeight;
    private final double price;

}

rods.yml

rod:
  1:
    name: "de Bambú"
    maxWeight: 10.0
    price: 0
  2:
    name: "de Grafite"
    maxWeight: 25.0
    price: 500
  3:
    name: "de Fibra de Vidro"
    maxWeight: 50.0
    price: 75000
  4:
    name: "de Fibra de Carbono"
    maxWeight: 100.0
    price: 2500000
  5:
    name: "Telescópica"
    maxWeight: 250.0
    price: 72500000