#vulnerable code 
                                public synchronized boolean saveApi(ApiResult apiResult) {
        boolean successful = false;

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        try {
            connection = this.dbConfig.getConnection();
            preparedStatement = connection.prepareStatement("INSERT INTO \"api\" (\"publickey\",\"privatekey\",\"lastused\",\"data\") VALUES (?,?,?,?)");

            preparedStatement.setString(1, apiResult.getPublicKey());
            preparedStatement.setString(2, apiResult.getPrivateKey());
            preparedStatement.setString(3, apiResult.getLastUsed());
            preparedStatement.setString(4, apiResult.getData());

            preparedStatement.execute();

            successful = true;
        }
        catch(SQLException ex) {
            Singleton.getLogger().severe(" caught a " + ex.getClass() + "\n with message: " + ex.getMessage());
        }
        finally {
            Helpers.closeQuietly(resultSet);
            Helpers.closeQuietly(preparedStatement);
        }

        return successful;
    } 
                            #location 25 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public synchronized boolean saveApi(ApiResult apiResult) {
        boolean successful = false;

        Connection connection;
        PreparedStatement preparedStatement = null;

        try {
            connection = this.dbConfig.getConnection();
            preparedStatement = connection.prepareStatement("INSERT INTO \"api\" (\"publickey\",\"privatekey\",\"lastused\",\"data\") VALUES (?,?,?,?)");

            preparedStatement.setString(1, apiResult.getPublicKey());
            preparedStatement.setString(2, apiResult.getPrivateKey());
            preparedStatement.setString(3, apiResult.getLastUsed());
            preparedStatement.setString(4, apiResult.getData());

            preparedStatement.execute();

            successful = true;
        }
        catch(SQLException ex) {
            Singleton.getLogger().severe(" caught a " + ex.getClass() + "\n with message: " + ex.getMessage());
        }
        finally {
            Helpers.closeQuietly(preparedStatement);
        }

        return successful;
    }