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In the case above, if an error occurs while executing the statement, or while processing the results of the statement, the connection is not closed. The use of a finally block can be used to ensure that close statements are eventually called.

Noncompliant Code Example

However, while being slightly better, this code is also non-compliant. Both rs and stmt might be null.

Statement stmt = null;
ResultSet rs = null
Connection conn = getConnection(0;
try {
    stmt = conn.createStatement();
    rs = stmt.executeQuery(sqlQuery);
    processResults(rs);
} catch(SQLException e) { }
  finally {
    rs.close();
    stmt.close();
}
}

Noncompliant Code Example

AgainHowever, while being slightly still better, this the code is also still non-compliant. Both rs and stmt might be nullThis is because rs.close() might itself result in a SQLException, and so stmt.close() will never be called.

Statement stmt = null;
ResultSet rs = null;
Connection conn = getConnection();
try {
    stmt = conn.createStatement();
    rs = stmt.executeQuery(sqlQuery);
    processResults(rs);
} catch(SQLException e) { }
  finally {
    if(rs != null) {
      rs.close();
    }
    if(stmt != null) {
      stmt.close();
    }
}
}

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Compliant Solution

This compliant solution shows how to ensure that resources have been released.

Statement stmt = null;
ResultSet rs = null;
Connection conn = getConnection();
try {
    stmt = conn.createStatement();
    rs = stmt.executeQuery(sqlQuery);
    processResults(rs);
} catch(SQLException e) { }
  finally {
     try {
       if(rs != null) {
        rs.close();
       }
     } finally (
        try {
          if(stmt != null) {
            stmt.close();
          }
        }
        finally {
           conn.close();
        }
      }
}

Noncompliant Code Example

The worst form of non-compliance is not calling methods to release the resource at all. If files are opened, they must be explicitly closed when their work is done.

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