ConfigManager.java

package chi.utils;

import java.io.*;
import java.util.HashMap;
import java.util.Properties;

public class ConfigManager {

    private final  File config_file;
    private static HashMap<String, String> preferences;
    private Properties props;

    public ConfigManager() {
        preferences = new HashMap<>();
        this.config_file = new File("./resources/config.properties");
        this.props = new Properties();

        OpenProperties();
        LoadProperties();
    }

    private void OpenProperties() {

        try (FileInputStream reader = new FileInputStream(config_file)) {

            props.load(reader);
            System.out.println(config_file.getName());

        } catch (FileNotFoundException e) {

            e.printStackTrace();
            System.err.format("Properties file {0}%s not found.", config_file.getName());
            System.exit(1);

        } catch (IOException e) {

            e.printStackTrace();
            System.err.format("Properties file {0}%s can not be loaded.", config_file.getName());
            System.exit(1);

        } finally {

            System.out.println("Properties file was successfully opened.");

        }
    }

    private void LoadProperties() {
        
        for (final String name : props.stringPropertyNames())
            preferences.put(name, props.getProperty(name));
    
    }

    public String getAttribute(String attributeName) {
        
        String attribute = preferences.get(attributeName);
        if (attribute != null) {

            return attribute;

        } else {

            System.out.println("Unable to read attribute, keyword not found.");
            return null;
            
        }
    }

    public void setAttribute(String attributeName, String value) throws FileNotFoundException {
        
        String attribute = preferences.get(attributeName);
        if (attribute != null) {

            props.setProperty(attributeName, value);

            try (FileOutputStream writer = new FileOutputStream(config_file)) {
                props.store(writer, "");
            } catch (IOException e) {
                e.printStackTrace();
            }

        } else {
            
            System.out.println("Unable to set attribute, keyword not found.");
        
        }
    }

}