Finished project.

.gitignore

+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
+
+### Static files ###
+resources/configuration.json
+resources/logs.txt
\ No newline at end of file

.idea/.gitignore

+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/dataSources.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="DataSourceManagerImpl" format="xml" multifile-model="true">
+    <data-source source="LOCAL" name="postgres@localhost" uuid="f036859d-60a1-42b5-b9bb-c14fbb3b5a02">
+      <driver-ref>postgresql</driver-ref>
+      <synchronize>true</synchronize>
+      <jdbc-driver>org.postgresql.Driver</jdbc-driver>
+      <jdbc-url>jdbc:postgresql://localhost:5432/postgres</jdbc-url>
+      <jdbc-additional-properties>
+        <property name="com.intellij.clouds.kubernetes.db.host.port" />
+        <property name="com.intellij.clouds.kubernetes.db.enabled" value="false" />
+        <property name="com.intellij.clouds.kubernetes.db.resource.type" value="Deployment" />
+        <property name="com.intellij.clouds.kubernetes.db.container.port" />
+      </jdbc-additional-properties>
+      <working-dir>$ProjectFileDir$</working-dir>
+    </data-source>
+  </component>
+</project>
\ No newline at end of file

.idea/inspectionProfiles/Project_Default.xml

+<component name="InspectionProjectProfileManager">
+  <profile version="1.0">
+    <option name="myName" value="Project Default" />
+    <inspection_tool class="ClassCanBeRecord" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
+    <inspection_tool class="Convert2Diamond" enabled="false" level="WARNING" enabled_by_default="false" />
+  </profile>
+</component>
\ No newline at end of file

.idea/libraries/gson_2_11_0.xml

+<component name="libraryTable">
+  <library name="gson-2.11.0">
+    <CLASSES>
+      <root url="jar://$PROJECT_DIR$/resources/lib/gson-2.11.0.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
\ No newline at end of file

.idea/libraries/postgresql_42_7_3.xml

+<component name="libraryTable">
+  <library name="postgresql-42.7.3">
+    <CLASSES>
+      <root url="jar://$PROJECT_DIR$/resources/lib/postgresql-42.7.3.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
\ No newline at end of file

.idea/misc.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="17" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
\ No newline at end of file

.idea/modules.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/application.iml" filepath="$PROJECT_DIR$/application.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file

.idea/sqldialects.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="SqlDialectMappings">
+    <file url="file://$PROJECT_DIR$/src/core/db/repositories/CarRepository.java" dialect="GenericSQL" />
+    <file url="PROJECT" dialect="PostgreSQL" />
+  </component>
+</project>
\ No newline at end of file

.idea/uiDesigner.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Palette2">
+    <group name="Swing">
+      <item class="com.intellij.uiDesigner.HSpacer" tooltip-text="Horizontal Spacer" icon="/com/intellij/uiDesigner/icons/hspacer.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="1" hsize-policy="6" anchor="0" fill="1" />
+      </item>
+      <item class="com.intellij.uiDesigner.VSpacer" tooltip-text="Vertical Spacer" icon="/com/intellij/uiDesigner/icons/vspacer.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="1" anchor="0" fill="2" />
+      </item>
+      <item class="javax.swing.JPanel" icon="/com/intellij/uiDesigner/icons/panel.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JScrollPane" icon="/com/intellij/uiDesigner/icons/scrollPane.svg" removable="false" auto-create-binding="false" can-attach-label="true">
+        <default-constraints vsize-policy="7" hsize-policy="7" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JButton" icon="/com/intellij/uiDesigner/icons/button.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="3" anchor="0" fill="1" />
+        <initial-values>
+          <property name="text" value="Button" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JRadioButton" icon="/com/intellij/uiDesigner/icons/radioButton.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="3" anchor="8" fill="0" />
+        <initial-values>
+          <property name="text" value="RadioButton" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JCheckBox" icon="/com/intellij/uiDesigner/icons/checkBox.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="3" anchor="8" fill="0" />
+        <initial-values>
+          <property name="text" value="CheckBox" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JLabel" icon="/com/intellij/uiDesigner/icons/label.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="0" anchor="8" fill="0" />
+        <initial-values>
+          <property name="text" value="Label" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JTextField" icon="/com/intellij/uiDesigner/icons/textField.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JPasswordField" icon="/com/intellij/uiDesigner/icons/passwordField.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JFormattedTextField" icon="/com/intellij/uiDesigner/icons/formattedTextField.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTextArea" icon="/com/intellij/uiDesigner/icons/textArea.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTextPane" icon="/com/intellij/uiDesigner/icons/textPane.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JEditorPane" icon="/com/intellij/uiDesigner/icons/editorPane.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JComboBox" icon="/com/intellij/uiDesigner/icons/comboBox.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="2" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JTable" icon="/com/intellij/uiDesigner/icons/table.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JList" icon="/com/intellij/uiDesigner/icons/list.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="2" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTree" icon="/com/intellij/uiDesigner/icons/tree.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTabbedPane" icon="/com/intellij/uiDesigner/icons/tabbedPane.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3">
+          <preferred-size width="200" height="200" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JSplitPane" icon="/com/intellij/uiDesigner/icons/splitPane.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3">
+          <preferred-size width="200" height="200" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JSpinner" icon="/com/intellij/uiDesigner/icons/spinner.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JSlider" icon="/com/intellij/uiDesigner/icons/slider.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JSeparator" icon="/com/intellij/uiDesigner/icons/separator.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JProgressBar" icon="/com/intellij/uiDesigner/icons/progressbar.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1" />
+      </item>
+      <item class="javax.swing.JToolBar" icon="/com/intellij/uiDesigner/icons/toolbar.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1">
+          <preferred-size width="-1" height="20" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JToolBar$Separator" icon="/com/intellij/uiDesigner/icons/toolbarSeparator.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="0" anchor="0" fill="1" />
+      </item>
+      <item class="javax.swing.JScrollBar" icon="/com/intellij/uiDesigner/icons/scrollbar.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="0" anchor="0" fill="2" />
+      </item>
+    </group>
+  </component>
+</project>
\ No newline at end of file

.idea/vcs.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file

application.iml

+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/resources" type="java-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="postgresql-42.7.3" level="project" />
+    <orderEntry type="library" name="gson-2.11.0" level="project" />
+  </component>
+</module>
\ No newline at end of file

resources/configuration-sample.json

+{
+  "db.url": "~",
+  "db.username": "~",
+  "db.password": "~"
+}
\ No newline at end of file

src/Main.java

+import core.Application;
+import core.utils.logs.Logger;
+
+import java.sql.SQLException;
+
+public class Main
+{
+    public static void main(String[] args)
+    {
+        try
+        {
+            Application application = new Application();
+            application.run();
+        }
+        catch (SQLException exception)
+        {
+            Logger.error("DB problem: " + exception.getMessage());
+            System.exit(exception.getErrorCode());
+        }
+    }
+}
\ No newline at end of file

src/core/Application.java

+package core;
+
+import core.db.repositories.CarRepository;
+import core.db.repositories.Repository;
+import core.models.Car;
+
+import java.sql.SQLException;
+import java.util.List;
+
+public class Application
+{
+    private final Repository<Car> repository;
+
+    public Application() throws SQLException
+    {
+        this.repository = new CarRepository();
+    }
+
+    public void run() throws SQLException
+    {
+        List<Car> cars = repository.get();
+
+        System.out.println("\nCars from DB:");
+        cars.forEach(System.out::println);
+
+        Car car = repository.get(1);
+
+        System.out.println("\nCar from DB by ID(1):");
+        System.out.println(car);
+    }
+}

src/core/configuration/ConfigurationMap.java

+package core.configuration;
+
+import com.google.gson.annotations.SerializedName;
+
+public class ConfigurationMap
+{
+    @SerializedName("db.url")
+    private final String url;
+
+    @SerializedName("db.username")
+    private final String username;
+
+    @SerializedName("db.password")
+    private final String password;
+
+    public ConfigurationMap(String url, String username, String password)
+    {
+        this.url = url;
+        this.username = username;
+        this.password = password;
+    }
+
+    public String getUrl()
+    {
+        return url;
+    }
+
+    public String getUsername()
+    {
+        return username;
+    }
+
+    public String getPassword()
+    {
+        return password;
+    }
+}

src/core/db/DBConnection.java

+package core.db;
+
+import core.configuration.ConfigurationMap;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+public class DBConnection
+{
+    private volatile Connection instance;
+
+    public DBConnection(ConfigurationMap configuration) throws SQLException
+    {
+        this.instance = open(
+                configuration.getUrl(),
+                configuration.getUsername(),
+                configuration.getPassword()
+        );
+    }
+
+    private DBConnection() {}
+
+    public Connection getInstance()
+    {
+        return instance;
+    }
+
+    private Connection open(String url, String username, String password) throws SQLException
+    {
+        Connection local = instance;
+
+        if (local == null)
+        {
+            synchronized (Connection.class)
+            {
+                local = instance;
+                if (local == null)
+                {
+                    instance = local = DriverManager.getConnection(url, username, password);
+                }
+            }
+        }
+
+        return local;
+    }
+
+    public void close() throws SQLException
+    {
+        instance.close();
+        instance = null;
+    }
+}

src/core/db/repositories/CarRepository.java

+package core.db.repositories;
+
+import core.models.Car;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+
+public class CarRepository extends Repository<Car>
+{
+    public CarRepository() throws SQLException
+    {
+        super();
+    }
+
+    @Override
+    public Car get(int id) throws SQLException
+    {
+        Statement statement = getStatement();
+
+        String query = "SELECT * FROM db.cars WHERE id = %d;".formatted(id);
+        ResultSet result = statement.executeQuery(query);
+
+        result.next();
+        Car car = map(result);
+        result.close();
+
+        return car;
+    }
+
+    @Override
+    public List<Car> get() throws SQLException
+    {
+        Statement statement = getStatement();
+
+        String query = "SELECT * FROM db.cars;";
+        ResultSet result = statement.executeQuery(query);
+
+        List<Car> cars = maps(result);
+        result.close();
+
+        return cars;
+    }
+
+    private Car map(ResultSet result) throws SQLException
+    {
+        return new Car(
+                result.getInt("id"),
+                result.getString("name"),
+                result.getString("type"),
+                result.getString("color"),
+                result.getFloat("volume")
+        );
+    }
+
+    private List<Car> maps(ResultSet result) throws SQLException
+    {
+        List<Car> cars = new ArrayList<Car>();
+
+        while (result.next())
+        {
+            cars.add(map(result));
+        }
+
+        return cars;
+    }
+}

src/core/db/repositories/Repository.java

+package core.db.repositories;
+
+import core.db.DBConnection;
+import core.utils.io.ConfigurationReader;
+
+import java.sql.*;
+import java.util.List;
+
+public abstract class Repository<T>
+{
+    private final Connection connection;
+
+    public Repository() throws SQLException
+    {
+        this.connection = new DBConnection(ConfigurationReader.get()).getInstance();
+    }
+
+    public abstract T get(int id) throws SQLException;
+
+    public abstract List<T> get() throws SQLException;
+
+    protected Statement getStatement() throws SQLException
+    {
+        return connection.createStatement();
+    }
+}

src/core/models/Car.java

+package core.models;
+
+public class Car
+{
+    private final int id;
+
+    private final String name;
+    private final String type;
+    private final String color;
+
+    private final float volume;
+
+    public Car(int id, String name, String type, String color, float volume)
+    {
+        this.id = id;
+
+        this.name = name;
+        this.type = type;
+        this.color = color;
+
+        this.volume = volume;
+    }
+
+    @Override
+    public String toString()
+    {
+        String format = "{\"id\": %d, \"name\": %s, \"type\":  %s, \"color\": %s, \"volume\": %.1f}";
+        return String.format(format, id, name, type, color, volume);
+    }
+}

src/core/utils/io/ConfigurationReader.java

+package core.utils.io;
+
+import com.google.gson.Gson;
+import core.configuration.ConfigurationMap;
+
+public class ConfigurationReader
+{
+    private static final Gson gson = new Gson();
+    private static final IOFileReader reader = new IOFileReader();
+
+    public static ConfigurationMap get()
+    {
+        String json = reader.read("resources/configuration.json");
+        return gson.fromJson(json, ConfigurationMap.class);
+    }
+}

src/core/utils/io/IOFileReader.java

+package core.utils.io;
+
+import core.utils.logs.Logger;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+public class IOFileReader
+{
+    public String read(String path)
+    {
+        try(BufferedReader reader = new BufferedReader(new FileReader(path)))
+        {
+            String line;
+
+            StringBuilder body = new StringBuilder();
+            while (true)
+            {
+                line = reader.readLine();
+
+                //null означает конец файла:
+                if (line == null)
+                {
+                    break;
+                }
+
+                body.append(line);
+            }
+
+            return body.toString();
+        }
+        catch (IOException exception)
+        {
+            Logger.error("Exception occurred while reading file " + path + " " + exception.getMessage());
+        }
+
+        return "Empty";
+    }
+}

src/core/utils/io/IOFileWriter.java

+package core.utils.io;
+
+import core.utils.logs.Logger;
+
+import java.io.BufferedWriter;
+import java.io.FileWriter;
+import java.io.IOException;
+
+public class IOFileWriter
+{
+    //Перезаписывает...
+    public void write(String path, String body)
+    {
+        try(BufferedWriter writer = new BufferedWriter(new FileWriter(path)))
+        {
+            writer.write(body);
+            writer.newLine();
+        }
+        catch (IOException exception)
+        {
+            Logger.error("Exception occurred while writing file " + path + " " + exception.getMessage());
+        }
+    }
+
+
+    //Дозаписывает...
+    public void append(String path, String body)
+    {
+        try(BufferedWriter writer = new BufferedWriter(new FileWriter(path, true)))
+        {
+            writer.append(body);
+            writer.newLine();
+        }
+        catch (IOException exception)
+        {
+            Logger.error("Exception occurred while writing file " + path + " " + exception.getMessage());
+        }
+    }
+}
\ No newline at end of file

src/core/utils/logs/Logger.java

+package core.utils.logs;
+
+import core.utils.io.IOFileWriter;
+
+import java.time.LocalDateTime;
+
+public class Logger
+{
+    private static final String PATH = "resources/logs.txt";
+    private static final IOFileWriter writer = new IOFileWriter();
+
+    public static void info(String message)
+    {
+        writer.append(PATH, "INFO - " + LocalDateTime.now() + " - " + message);
+    }
+
+    public static void error(String message)
+    {
+        writer.append(PATH, "ERROR - " + LocalDateTime.now() + " - " + message);
+    }
+}
\ No newline at end of file