Merge 'bindings/java: Clean up ' from Kim Seon Woo

- Add finals to classes where we don't want users to inherit
- Make `JDBC4ResultSet` to implement `ResultSetMetaData` and add TODOs

Closes #1045

bindings/java/src/main/java/tech/turso/JDBC.java

@@ -9,7 +9,7 @@ import tech.turso.jdbc4.JDBC4Connection;
 import tech.turso.utils.Logger;
 import tech.turso.utils.LoggerFactory;
 
-public class JDBC implements Driver {
+public final class JDBC implements Driver {
   private static final Logger logger = LoggerFactory.getLogger(JDBC.class);
 
   private static final String VALID_URL_PREFIX = "jdbc:sqlite:";

bindings/java/src/main/java/tech/turso/LimboConfig.java

@@ -5,7 +5,7 @@ import java.util.Arrays;
 import java.util.Properties;
 
 /** Limbo Configuration. */
-public class LimboConfig {
+public final class LimboConfig {
   private final Properties pragma;
 
   public LimboConfig(Properties properties) {

bindings/java/src/main/java/tech/turso/LimboDataSource.java

@@ -11,7 +11,7 @@ import tech.turso.annotations.Nullable;
 import tech.turso.annotations.SkipNullableCheck;
 
 /** Provides {@link DataSource} API for configuring Limbo database connection. */
-public class LimboDataSource implements DataSource {
+public final class LimboDataSource implements DataSource {
 
   private final LimboConfig limboConfig;
   private final String url;

bindings/java/src/main/java/tech/turso/core/LimboConnection.java

@@ -10,7 +10,7 @@ import tech.turso.utils.LimboExceptionUtils;
 import tech.turso.utils.Logger;
 import tech.turso.utils.LoggerFactory;
 
-public class LimboConnection {
+public final class LimboConnection {
   private static final Logger logger = LoggerFactory.getLogger(LimboConnection.class);
 
   private final String url;

bindings/java/src/main/java/tech/turso/core/LimboDBFactory.java

@@ -8,7 +8,7 @@ import java.util.concurrent.ConcurrentHashMap;
  * Factory class for managing and creating instances of {@link LimboDB}. This class ensures that
  * multiple instances of {@link LimboDB} with the same URL are not created.
  */
-public class LimboDBFactory {
+public final class LimboDBFactory {
 
   private static final ConcurrentHashMap<String, LimboDB> databaseHolder =
       new ConcurrentHashMap<>();

bindings/java/src/main/java/tech/turso/core/LimboResultSet.java

@@ -13,7 +13,7 @@ import tech.turso.utils.LoggerFactory;
  * <p>A {@link LimboResultSet} object is automatically closed when the {@link LimboStatement} object
  * that generated it is closed or re-executed.
  */
-public class LimboResultSet {
+public final class LimboResultSet {
 
   private static final Logger log = LoggerFactory.getLogger(LimboResultSet.class);
 

bindings/java/src/main/java/tech/turso/core/LimboStatement.java

@@ -14,7 +14,7 @@ import tech.turso.utils.LoggerFactory;
  * objects. All execution method in the <code>LimboStatement</code> implicitly close the current
  * <code>resultSet</code> object of the statement if an open one exists.
  */
-public class LimboStatement {
+public final class LimboStatement {
   private static final Logger log = LoggerFactory.getLogger(LimboStatement.class);
 
   private final String sql;

bindings/java/src/main/java/tech/turso/core/LimboStepResult.java

@@ -5,7 +5,7 @@ import tech.turso.annotations.NativeInvocation;
 import tech.turso.annotations.Nullable;
 
 /** Represents the step result of limbo's statement's step function. */
-public class LimboStepResult {
+public final class LimboStepResult {
   private static final int STEP_RESULT_ID_ROW = 10;
   private static final int STEP_RESULT_ID_IO = 20;
   private static final int STEP_RESULT_ID_DONE = 30;

bindings/java/src/main/java/tech/turso/core/SqliteCode.java

@@ -16,7 +16,7 @@
 package tech.turso.core;
 
 /** Sqlite error codes. */
-public class SqliteCode {
+public final class SqliteCode {
   /** Successful result */
   public static final int SQLITE_OK = 0;
 

bindings/java/src/main/java/tech/turso/exceptions/LimboException.java

@@ -3,7 +3,7 @@ package tech.turso.exceptions;
 import java.sql.SQLException;
 import tech.turso.LimboErrorCode;
 
-public class LimboException extends SQLException {
+public final class LimboException extends SQLException {
   private final LimboErrorCode resultCode;
 
   public LimboException(String message, LimboErrorCode resultCode) {

bindings/java/src/main/java/tech/turso/jdbc4/JDBC4Connection.java

@@ -9,7 +9,7 @@ import tech.turso.annotations.SkipNullableCheck;
 import tech.turso.core.LimboConnection;
 import tech.turso.core.LimboStatement;
 
-public class JDBC4Connection implements Connection {
+public final class JDBC4Connection implements Connection {
 
   private final LimboConnection connection;
 
@@ -87,8 +87,7 @@ public class JDBC4Connection implements Connection {
   @Override
   @SkipNullableCheck
   public DatabaseMetaData getMetaData() throws SQLException {
-    // TODO
-    return null;
+    return new JDBC4DatabaseMetaData(this);
   }
 
   @Override

bindings/java/src/main/java/tech/turso/jdbc4/JDBC4DatabaseMetaData.java

@@ -15,7 +15,7 @@ import tech.turso.annotations.SkipNullableCheck;
 import tech.turso.utils.Logger;
 import tech.turso.utils.LoggerFactory;
 
-public class JDBC4DatabaseMetaData implements DatabaseMetaData {
+public final class JDBC4DatabaseMetaData implements DatabaseMetaData {
 
   private static final Logger logger = LoggerFactory.getLogger(JDBC4DatabaseMetaData.class);
 

bindings/java/src/main/java/tech/turso/jdbc4/JDBC4PreparedStatement.java

@@ -25,7 +25,7 @@ import java.util.Calendar;
 import tech.turso.annotations.SkipNullableCheck;
 import tech.turso.core.LimboResultSet;
 
-public class JDBC4PreparedStatement extends JDBC4Statement implements PreparedStatement {
+public final class JDBC4PreparedStatement extends JDBC4Statement implements PreparedStatement {
 
   private final String sql;
 

bindings/java/src/main/java/tech/turso/jdbc4/JDBC4ResultSet.java

@@ -26,7 +26,7 @@ import tech.turso.annotations.Nullable;
 import tech.turso.annotations.SkipNullableCheck;
 import tech.turso.core.LimboResultSet;
 
-public class JDBC4ResultSet implements ResultSet {
+public final class JDBC4ResultSet implements ResultSet, ResultSetMetaData {
 
   private final LimboResultSet resultSet;
 
@@ -310,10 +310,8 @@ public class JDBC4ResultSet implements ResultSet {
   }
 
   @Override
-  @SkipNullableCheck
   public ResultSetMetaData getMetaData() throws SQLException {
-    // TODO
-    return null;
+    return this;
   }
 
   @Override
@@ -1181,6 +1179,131 @@ public class JDBC4ResultSet implements ResultSet {
     return false;
   }
 
+  @Override
+  public int getColumnCount() throws SQLException {
+    return this.resultSet.getColumnNames().length;
+  }
+
+  @Override
+  public boolean isAutoIncrement(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public boolean isCaseSensitive(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public boolean isSearchable(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public boolean isCurrency(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public int isNullable(int column) throws SQLException {
+    // TODO
+    return 0;
+  }
+
+  @Override
+  public boolean isSigned(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public int getColumnDisplaySize(int column) throws SQLException {
+    // TODO
+    return 0;
+  }
+
+  @Override
+  public String getColumnLabel(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
+  @Override
+  public String getColumnName(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
+  @Override
+  public String getSchemaName(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
+  @Override
+  public int getPrecision(int column) throws SQLException {
+    // TODO
+    return 0;
+  }
+
+  @Override
+  public int getScale(int column) throws SQLException {
+    // TODO
+    return 0;
+  }
+
+  @Override
+  public String getTableName(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
+  @Override
+  public String getCatalogName(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
+  @Override
+  public int getColumnType(int column) throws SQLException {
+    // TODO
+    return 0;
+  }
+
+  @Override
+  public String getColumnTypeName(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
+  @Override
+  public boolean isReadOnly(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public boolean isWritable(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public boolean isDefinitelyWritable(int column) throws SQLException {
+    // TODO
+    return false;
+  }
+
+  @Override
+  public String getColumnClassName(int column) throws SQLException {
+    // TODO
+    return "";
+  }
+
   @FunctionalInterface
   public interface ResultSetSupplier<T> {
     T get() throws Exception;

bindings/java/src/main/java/tech/turso/utils/ByteArrayUtils.java

@@ -3,7 +3,7 @@ package tech.turso.utils;
 import java.nio.charset.StandardCharsets;
 import tech.turso.annotations.Nullable;
 
-public class ByteArrayUtils {
+public final class ByteArrayUtils {
   @Nullable
   public static String utf8ByteBufferToString(@Nullable byte[] buffer) {
     if (buffer == null) {

bindings/java/src/main/java/tech/turso/utils/LimboExceptionUtils.java

@@ -7,7 +7,7 @@ import tech.turso.LimboErrorCode;
 import tech.turso.annotations.Nullable;
 import tech.turso.exceptions.LimboException;
 
-public class LimboExceptionUtils {
+public final class LimboExceptionUtils {
   /**
    * Throws formatted SQLException with error code and message.
    *

bindings/java/src/main/java/tech/turso/utils/LoggerFactory.java

@@ -6,7 +6,7 @@ import java.util.logging.Level;
  * A factory for {@link Logger} instances that uses SLF4J if present, falling back on a
  * java.util.logging implementation otherwise.
  */
-public class LoggerFactory {
+public final class LoggerFactory {
   static final boolean USE_SLF4J;
 
   static {