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POJava using JDBC - Too many connections?
 

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  1. POJava using JDBC - Too many connections?
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    <p>I am writing a stock replenishment system for a bar as my final year project. I can retrieve information from a MYSQL database and I can scroll through one result at a time.</p> <p>I'm trying to change the results depending on a selected category. I've managed to use a combo box to acheive this but I get the following error when moving between categories:</p> <blockquote> <p>Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"</p> </blockquote> <p>The code for the two separate files are as follows:</p> <ul> <li><p>The SQL queries in <code>RetrieveStockQuery</code></p> <pre><code>public JComboBox getComboBox() throws SQLException { con = SQLConnect.getConnection(); combo = new JComboBox(); combo.removeAllItems(); try { stat = con.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE ); rs = stat.executeQuery("SELECT categoryName FROM Category"); while (rs.next()) { combo.addItem(rs.getString("categoryName")); categoryName = rs.getString("categoryName"); } } catch (SQLException sqle) { System.out.println(sqle); stat.close(); con.close(); } return combo; } //---------------------------------------------------------------- public void retrieveStock() throws SQLException { con = SQLConnect.getConnection(); stockGUI = new ViewStockGUI(); // I THINK THIS IS WHAT IS CAUSING THE ERROR String viewStock = "SELECT * FROM Stock where categoryName = '" + "'" + stockGUI.selected + "'"; System.out.println(viewStock); try { stat = con.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE ); rs = stat.executeQuery(viewStock); while(rs.next()){ stockID = rs.getInt("stockID"); stockName = rs.getString("stockName"); stockDescription = rs.getString("stockDescription"); stockPrice = rs.getFloat("stockPrice"); stockQuantity = rs.getInt("stockQuantity"); categoryName = rs.getString("categoryName"); ID = Integer.toString(stockID); price = Float.toString(stockPrice); quantity = Double.toString(stockQuantity); stat.close(); con.close(); System.out.println( "Stock ID: " + stockID + " Stock Name: " + stockName + " Stock Description: " + stockDescription + " Stock Price: " + stockPrice + " Stock Quantity:" + stockQuantity + " Category: " + categoryName); } } catch (SQLException err) { System.out.println(err.getMessage()); } } </code></pre></li> <li><p>My <code>ViewStockGUI</code> class</p> <pre><code> public class ViewStockGUI extends JPanel { private static final long serialVersionUID = 1L; final JFrame viewFrame; ViewStockQuery stockQuery; ViewStockQuery stockName; JComboBox comboGUI; String selected; JComboBox combo; public ViewStockGUI() throws SQLException { final ViewStockQuery stock = new ViewStockQuery(); comboGUI = stock.getComboBox(); stock.retrieveStock(); viewFrame = new JFrame("View Stock"); JPanel p = new JPanel(); p.setBorder (new TitledBorder(new LineBorder(Color.black, 1, true))); p.setPreferredSize(new Dimension(500,400)); JPanel p2 = new JPanel(); p2.setBorder (new TitledBorder(new LineBorder(Color.black, 1, true))); p2.setPreferredSize(new Dimension(500, 50)); JPanel p3 = new JPanel(); JPanel p4 = new JPanel(); JPanel p5 = new JPanel(); JPanel p6 = new JPanel(); Box box = Box.createVerticalBox(); Box box2 = Box.createHorizontalBox(); Box box3 = Box.createHorizontalBox(); Box box4 = Box.createHorizontalBox(); final JTextField textfieldStockName; final JTextField textfieldStockID; final JTextField textfieldStockDescription; final JTextField textfieldStockPrice; final JTextField textfieldStockQuantity; final JTextField textfieldStockCategory; final JLabel stockName = new JLabel("Name:"); JLabel stockID = new JLabel("ID:"); JLabel stockDescription = new JLabel("Description:"); JLabel stockPrice = new JLabel("Price:"); JLabel stockQuantity = new JLabel("Quantity:"); JLabel categoryName = new JLabel("Category:"); box.add(Box.createVerticalGlue()); box.add(stockName); box.add(textfieldStockName = new JTextField("")); textfieldStockName.setText(stock.getStockName()); textfieldStockName.setEditable(false); box.add(stockID); box.add(textfieldStockID = new JTextField("")); textfieldStockID.setText(stock.getStockID()); textfieldStockID.setEditable(false); box.add(stockDescription); box.add(textfieldStockDescription = new JTextField("")); textfieldStockDescription.setText(stock.getStockDescription()); textfieldStockDescription.setEditable(false); box.add(stockPrice); box.add(textfieldStockPrice = new JTextField("")); textfieldStockPrice.setText(stock.getStockPrice()); textfieldStockPrice.setEditable(false); box.add(stockQuantity); box.add(textfieldStockQuantity = new JTextField("")); textfieldStockQuantity.setText(stock.getStockQuantity()); textfieldStockQuantity.setEditable(false); box.add(categoryName); box.add(textfieldStockCategory = new JTextField("")); textfieldStockCategory.setText(stock.getStockCategory()); textfieldStockCategory.setEditable(false); box.add(Box.createVerticalGlue()); JButton next = new JButton("Next"); next.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { stock.doNext(); textfieldStockName.setText(stock.getStockName()); textfieldStockID.setText(stock.getStockID()); textfieldStockDescription.setText(stock.getStockDescription()); textfieldStockPrice.setText(stock.getStockPrice()); textfieldStockQuantity.setText(stock.getStockQuantity()); textfieldStockCategory.setText(stock.getStockCategory()); } }); JButton previous = new JButton("Previous"); previous.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { stock.doPrevious(); textfieldStockName.setText(stock.getStockName()); textfieldStockID.setText(stock.getStockID()); textfieldStockDescription.setText(stock.getStockDescription()); textfieldStockPrice.setText(stock.getStockPrice()); textfieldStockQuantity.setText(stock.getStockQuantity()); textfieldStockCategory.setText(stock.getStockCategory()); } }); final Counter counter = new Counter(); final JLabel text = new JLabel(counter.getValue1()); JButton plus = new JButton("+"); plus.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { counter.increment(); text.setText(counter.getValue1()); } }); JButton minus = new JButton("-"); minus.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { counter.decrease(); text.setText(counter.getValue1()); } }); JButton update = new JButton("Update"); update.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { try { stock.updateStock(counter.getValue1()); } catch (SQLException e1) { e1.printStackTrace(); } finally { // doesn't update yet; will work on this later textfieldStockQuantity.setText(stock.getStockQuantity()); } } }); comboGUI.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { try { combo = (JComboBox) e.getSource(); selected = (String)combo.getSelectedItem(); textfieldStockName.setText(stock.getStockName()); textfieldStockID.setText(stock.getStockID()); textfieldStockDescription.setText(stock.getStockDescription()); textfieldStockPrice.setText(stock.getStockPrice()); textfieldStockQuantity.setText(stock.getStockQuantity()); textfieldStockCategory.setText(stock.getStockCategory()); stockQuery.con.close(); } catch (SQLException e1) { e1.printStackTrace(); } } }); box.add(comboGUI); box2.add(previous); box2.add(next); box3.add(minus); box3.add(text); box3.add(plus); box4.add(update); p.add(box2); p.add(box); p.add(box3); p.add(box4); this.add(p, BorderLayout.SOUTH); } } </code></pre></li> </ul> <p>If anyone can help it would be appreciated.</p>
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    1. COCan you show us the code of `SQLConnect.getConnection();`?
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    2. COpossible duplicate of [Data source rejected establishment of connection, message from server: "Too many connections"](http://stackoverflow.com/questions/3203673/data-source-rejected-establishment-of-connection-message-from-server-too-many)
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    3. COWhy is the connection close inside the while loop ? It should be in the finally block of try catch.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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