即使我们已经处理了语句，SonarLint 仍然显示阻止程序错误，连接在 finally 块中关闭

Question

SonarLint is showing below errors:

1. 'Use try-with-resources or close this "Statement" in a "finally" clause.'
2. 'Use try-with-resources or close this "Connection" in a "finally" clause.'
   blocker errors even though we have closed the Statement stmt, Connection con in finally block.

Please find the sample code.

public String getProductNumber() throws BusinessDelegateException {

        String productNo = null;
        Connection con = null;
        Statement stmt = null;
        ResultSet   rs  = null;
        String query  = //some query
        try {
            DataSource ds = getDataSource();
            con = ds.getConnection();
            stmt = con.createStatement();
            rs   = stmt.executeQuery(query);
            productNo =.......
            ....................
        }catch (Exception e) {
            String errorMsg = "Error occured in getProductNumber()";
            throw new BusinessDelegateException(errorMsg, e);
        }finally{
            try {
                if(rs != null)
                    rs.close();
                if (stmt != null)
                    stmt.close();
                if (con != null)
                    con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        return productNo;
    }

We were able to fix the issue by modifying the finally block in below manner. But still it seems like repetition of catch blocks. Any other way we can fix this?

finally{
        try {
            if(rs != null)
                rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (stmt != null)
                stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (con != null)
                con.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

Answer 1

Without try-with-resources you can only improve the code by using methods for re-usability, call main method:

closeResources(rs, stmt, con);

Which will call each for each resource a different method for example Statement:

 public void closeResource(Statement stmt) {
    if (stmt != null) {
        stmt.close();
    } catch (SQLException e) {
        e.printStackTrace();
    }

BTW, you better use logger instead of e.printStackTrace()

For complete solution, you can check extensive example which add resources in array and close them in a loop:

 for (Closeable resource : resources) { try { resource.close(); 

Answer 2

Use Try-with-resources. This is the best option.