Close statement when closing result set

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [PR #43](https://github.com/itsallcode/simple-jdbc/pull/43): Allow direct access to `Connection` from `DbOperations`
 - [PR #44](https://github.com/itsallcode/simple-jdbc/pull/44): Add `GenericDialect` for unsupported databases
 - [PR #45](https://github.com/itsallcode/simple-jdbc/pull/45): Rename `executeStatement()` to `executeUpdate()` and return row count (**Breaking change**)
+- [PR #46](https://github.com/itsallcode/simple-jdbc/pull/46): Close `Statement` / `PreparedStatement` when closing the result set.
 
 ## [0.9.0] - 2024-12-23
 

src/main/java/org/itsallcode/jdbc/ConnectionWrapper.java

@@ -61,7 +61,6 @@ void executeScript(final String sqlScript) {
     SimpleResultSet<Row> query(final String sql) {
         LOG.finest(() -> "Executing query '" + sql + "'...");
         final SimpleStatement statement = createSimpleStatement();
-        // TODO: close statement when resultset is closed
         return statement.executeQuery(sql, ContextRowMapper.create(ContextRowMapper.generic(dialect)));
     }
 
@@ -70,7 +69,6 @@ <T> SimpleResultSet<T> query(final String sql, final PreparedStatementSetter pre
         LOG.finest(() -> "Executing query '" + sql + "'...");
         final SimplePreparedStatement statement = prepareStatement(sql);
         statement.setValues(preparedStatementSetter);
-        // TODO: close statement when resultset is closed
         return statement.executeQuery(ContextRowMapper.create(rowMapper));
     }
 

src/main/java/org/itsallcode/jdbc/SimplePreparedStatement.java

@@ -26,7 +26,7 @@ public class SimplePreparedStatement implements AutoCloseable {
     <T> SimpleResultSet<T> executeQuery(final ContextRowMapper<T> rowMapper) {
         final ResultSet resultSet = doExecuteQuery();
         final ResultSet convertingResultSet = ConvertingResultSet.create(dialect, resultSet);
-        return new SimpleResultSet<>(context, convertingResultSet, rowMapper);
+        return new SimpleResultSet<>(context, convertingResultSet, rowMapper, this);
     }
 
     private ResultSet doExecuteQuery() {

src/main/java/org/itsallcode/jdbc/SimpleStatement.java

@@ -23,7 +23,7 @@ public class SimpleStatement implements AutoCloseable {
     <T> SimpleResultSet<T> executeQuery(final String sql, final ContextRowMapper<T> rowMapper) {
         final ResultSet resultSet = doExecuteQuery(sql);
         final ResultSet convertingResultSet = ConvertingResultSet.create(dialect, resultSet);
-        return new SimpleResultSet<>(context, convertingResultSet, rowMapper);
+        return new SimpleResultSet<>(context, convertingResultSet, rowMapper, this);
     }
 
     private ResultSet doExecuteQuery(final String sql) {

src/main/java/org/itsallcode/jdbc/resultset/SimpleResultSet.java

@@ -19,6 +19,7 @@ public class SimpleResultSet<T> implements AutoCloseable, Iterable<T> {
     private final ResultSet resultSet;
     private final ContextRowMapper<T> rowMapper;
     private final Context context;
+    private final AutoCloseable statement;
     private Iterator<T> iterator;
 
     /**
@@ -27,11 +28,15 @@ public class SimpleResultSet<T> implements AutoCloseable, Iterable<T> {
      * @param context   database context
      * @param resultSet the underlying result set
      * @param rowMapper a row mapper for converting each row
+     * @param statement the statement that created the result set. This will be
+     *                  closed when the result set is closed.
      */
-    public SimpleResultSet(final Context context, final ResultSet resultSet, final ContextRowMapper<T> rowMapper) {
+    public SimpleResultSet(final Context context, final ResultSet resultSet, final ContextRowMapper<T> rowMapper,
+            final AutoCloseable statement) {
         this.context = context;
         this.resultSet = resultSet;
         this.rowMapper = rowMapper;
+        this.statement = statement;
     }
 
     /**
@@ -71,7 +76,7 @@ public Stream<T> stream() {
     }
 
     /**
-     * Close the underlying {@link ResultSet}.
+     * Close the underlying {@link ResultSet} and the statement that created it.
      * 
      * @throws UncheckedSQLException if closing fails.
      */
@@ -82,6 +87,11 @@ public void close() {
         } catch (final SQLException e) {
             throw new UncheckedSQLException("Error closing resultset", e);
         }
+        try {
+            statement.close();
+        } catch (final Exception e) {
+            throw new IllegalStateException("Error closing statement: " + e.getMessage(), e);
+        }
     }
 
     private boolean next() {

src/test/java/org/itsallcode/jdbc/SimplePreparedStatementTest.java

@@ -39,6 +39,15 @@ void executeQuery() throws SQLException {
         verify(statementMock).executeQuery();
     }
 
+    @Test
+    void closingResultSetClosesStatement() throws SQLException {
+        when(statementMock.executeQuery()).thenReturn(resultSetMock);
+        when(resultSetMock.getMetaData()).thenReturn(metaDataMock);
+        testee().executeQuery(rowMapperMock).close();
+
+        verify(statementMock).close();
+    }
+
     @Test
     void executeQueryFails() throws SQLException {
         when(statementMock.executeQuery()).thenThrow(new SQLException("expected"));

src/test/java/org/itsallcode/jdbc/SimpleStatementTest.java

@@ -36,6 +36,14 @@ void executeQuery() throws SQLException {
         verify(stmtMock).executeQuery("sql");
     }
 
+    @Test
+    void closingResultSetClosesStatement() throws SQLException {
+        when(stmtMock.executeQuery("sql")).thenReturn(resultSetMock);
+        when(resultSetMock.getMetaData()).thenReturn(metaDataMock);
+        testee().executeQuery("sql", rowMapperMock).close();
+        verify(stmtMock).close();
+    }
+
     @Test
     void executeQueryFails() throws SQLException {
         when(stmtMock.executeQuery("sql")).thenThrow(new SQLException("expected"));

src/test/java/org/itsallcode/jdbc/resultset/SimpleResultSetTest.java

@@ -5,8 +5,7 @@
 import static org.mockito.ArgumentMatchers.*;
 import static org.mockito.Mockito.*;
 
-import java.sql.ResultSet;
-import java.sql.SQLException;
+import java.sql.*;
 
 import org.itsallcode.jdbc.UncheckedSQLException;
 import org.junit.jupiter.api.Test;
@@ -18,12 +17,14 @@
 class SimpleResultSetTest {
 
     @Mock
-    private ResultSet resultSetMock;
+    ResultSet resultSetMock;
     @Mock
-    private ContextRowMapper<TestingRowType> rowMapper;
+    ContextRowMapper<TestingRowType> rowMapper;
+    @Mock
+    Statement statementMock;
 
     SimpleResultSet<TestingRowType> testee() {
-        return new SimpleResultSet<>(null, resultSetMock, rowMapper);
+        return new SimpleResultSet<>(null, resultSetMock, rowMapper, statementMock);
     }
 
     @Test
@@ -69,18 +70,45 @@ void closeSucceeds() throws SQLException {
         verify(resultSetMock).close();
     }
 
+    @Test
+    void closeClosesStatement() throws SQLException {
+        testee().close();
+        verify(statementMock).close();
+    }
+
+    @Test
+    void closingStatementFails() throws SQLException {
+        doThrow(new SQLException("expected")).when(statementMock).close();
+        final SimpleResultSet<TestingRowType> testee = testee();
+        assertThatThrownBy(testee::close)
+                .isInstanceOf(IllegalStateException.class)
+                .hasMessage("Error closing statement: expected");
+    }
+
     @Test
     void streamClosesResultSet() throws SQLException {
         testee().stream().close();
         verify(resultSetMock).close();
     }
 
+    @Test
+    void streamClosesStatement() throws SQLException {
+        testee().stream().close();
+        verify(statementMock).close();
+    }
+
     @Test
     void toListClosesResultSet() throws SQLException {
         testee().toList();
         verify(resultSetMock).close();
     }
 
+    @Test
+    void toListClosesStatement() throws SQLException {
+        testee().toList();
+        verify(statementMock).close();
+    }
+
     private void simulateRowMapper() throws SQLException {
         when(rowMapper.mapRow(eq(null), same(resultSetMock), anyInt()))
                 .thenAnswer(invocation -> new TestingRowType(invocation.getArgument(2, Integer.class)));