Do I Need to Close ResultSets and Statements Separately When Closing a JDBC Connection?

JDBC Resource Management: Must ResultSets and Statements be Closed Separately Even When Connection is Closed?

It is essential to practice proper resource management when working with JDBC. While closing the connection after usage is widely recommended, it begs the question: does closing the connection automatically close associated ResultSets and Statements?

The Importance of Separate Closures

Although closing the connection may seem sufficient, for optimal resource management, it is crucial to close the ResultSet and Statement separately. The reason lies in potential issues that can arise in certain database pooling scenarios:

Primitive Pooling and Incomplete Cleanup

When employing a "primitive" database pooling mechanism, calling connection.close() returns the connection to the pool without closing the associated ResultSet or Statement. This leaves resources unmanaged and can lead to unforeseen problems.

Recommended Practice

To ensure proper resource management, it is highly recommended to explicitly close the ResultSet and Statement before closing the connection, as demonstrated in the provided code snippet:

try {
    conn = // Retrieve connection
    stmt = conn.prepareStatement(// Some SQL);
    rs = stmt.executeQuery();
} catch(Exception e) {
    // Error Handling
} finally {
    try { if (rs != null) rs.close(); } catch (Exception e) {};
    try { if (stmt != null) stmt.close(); } catch (Exception e) {};
    try { if (conn != null) conn.close(); } catch (Exception e) {};
}

By following this practice, you guarantee the proper cleanup of all JDBC resources, even in the presence of primitive database pooling implementation.

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