How can I dynamicly add control elements to a form

Question

Hello,
I want to dynamicly add elements to a JPanel.
The elements with the properties are stored in a database
each record contains one element
Label
Combobox
Checkbox
I`m programming in NetBeans 5.5
Something like:
public void test()
try
stmt = GeneralDBConnect.createStatement();
ResultSet rs = stmt.executeQuery("select device_option_id, objecttype, device_option, size, location, tooltip from device_option where ...");
int i = 0;
if(rs.next())
i = i + 1;
switch(rs.getString(2))
case "Label" : JLabel Element[i] = new JLabel();
Element.setText(rs.getString(3));
break;
case "Textbox" : JTextField Element[i] = new JTextField();
break;
case "Combobox" : JComboBox Element[i] = new JCombobox();
Element[i].setToolTipText(rs.getString(6));
ResultSet List = stmt.executeQuery("select device_option_value_id, option_value from device_option_value where ...");
while(List.next)
Element[i].addItem(List.getString(2));
List.close();
break;
case "Checkbox" : JCheckBox Element[i] = new JCheckBox();
break;
jPanel_Device_Option.add(Element[i])
rs.close();
stmt.close();
catch (SQLException ex)
ex.printStackTrace();
I know the Element[i] is wrong code but I need to give the elements an unique name.
Can anyone assist me in this matter

Answer 1

Hello everybody,
I figured it out. I had to change the layout model of the JPanel.
I`ve chosen to use the gridbaglayout because its very flexibel. See http://java.sun.com/docs/books/tutorial/uiswing/layout/gridbag.html
Here is my code:
Description:
Whenever an item in a Combobox is changed (representing devices) the optional elements (a collection of Textfields, checkboxes, comboboxes) are shown in a JPanel.
Which Elements are shown is stored in a database. (Tabels device, device_option and device_option_value (stores the JCombobox items))
First create a JPanel in the graphical editor and right click it choose set layout\gridbaglayout
        jPanel_Device_Option.setLayout(new java.awt.GridBagLayout());
        jPanel_Device_Option.setBorder(javax.swing.BorderFactory.createTitledBorder("Device Options"));
        jPanel_Device_Option.setAutoscrolls(true);Then to create an empty border so the elements don`t clip to the edge of the JPanel add the following code in the properties window in the code section under node "Post-Init code"
        Border bBorder = jPanel_Device_Option.getBorder();
        Border bMargin = new EmptyBorder(0,10,0,10);
        jPanel_Device_Option.setBorder(new CompoundBorder(bBorder, bMargin));Then declare the public variables at the beginning of the code
    public static ArrayList aDatasetElements;
    public static JLabel[] aLabel;
    public static JLabel[] aTextfieldLabel;
    public static JTextField[] aTextfield;
    public static JLabel[] aComboboxLabel;
    public static JComboBox[] aCombobox;
    public static JLabel[] aCheckboxLabel;
    public static JCheckBox[] aCheckbox;And now the method that`s creating the elements
  public void setOutputSettings()
      jPanel_Device_Option.removeAll();//Clear all existing elements from the JPanel
      jPanel_Device_Option.repaint();//Refresh the JPanel
      if(jComboBox_Output.getSelectedItem().toString().length() > 0)//Check if any elements should be added
          GridBagConstraints gbConstraint = new GridBagConstraints();//Create a new gridbagcontraint (properties of layout) check http://java.sun.com/docs/books/tutorial/uiswing/layout/gridbag.html
          gbConstraint.fill = GridBagConstraints.HORIZONTAL;
          gbConstraint.anchor = GridBagConstraints.PAGE_START;
          gbConstraint.weightx = 0.5;
          try
              stmt = GeneralDBConnect.createStatement();
              /*Collect data from the database (Which elements should be displayed)  
                  deviceoption: The name of the option this is displayed in the elements label as text
                  tooltip: Show a tooltip on both label and element
                  device_optio_id: gets the ID needed to get the list values for a combobox also easy to use when getting the data afterwards (stored in a public variable
                  objecttype: Label, Textfield, Checkbox, Combobox*/
              ResultSet rsElements = stmt.executeQuery("select device_option, tooltip, device_option_id, objecttype from device_option where deviceid = (select device_id from device where devicename = \'" + jComboBox_Output.getSelectedItem() + "\') order by sequence_order asc");
              aDatasetElements = new ArrayList(); // Makes an array
              while(rsElements.next()) //get data in arraylist (a resultset closes after a while (garbitch collector) resulting in errors I recieved some errors resulset allready closed. Also needed to acces data afterwards
                  aDatasetElements.add(new String(rsElements.getString(1)) + " ;" + new String(rsElements.getString(2)) + ";" + new Integer(rsElements.getInt(3)) + ";" + new String(rsElements.getString(4)));
              rsElements.close();
              aLabel = new JLabel[aDatasetElements.size()];          //Makes an array
              aTextfieldLabel = new JLabel[aDatasetElements.size()]; //Makes an array
              aTextfield = new JTextField[aDatasetElements.size()];  //Makes an array
              aCheckboxLabel = new JLabel[aDatasetElements.size()];  //Makes an array
              aCheckbox = new JCheckBox[aDatasetElements.size()];    //Makes an array
              aComboboxLabel = new JLabel[aDatasetElements.size()];  //Makes an array
              aCombobox = new JComboBox[aDatasetElements.size()];    //Makes an array
              for(int i = 0; i < aDatasetElements.size(); i++) //loop through the foundset
                  String sDatasetElements = aDatasetElements.get(i).toString(); //get the data from the array
                  //Creation of Elements of type Label
                  if(sDatasetElements.split(";")[3].equals("Label")) //Check objecttype
                      gbConstraint.gridx = 0; //X position in layout (Label)
                      gbConstraint.gridy = i; //Y position in layout (Label)
                      aLabel[i] = new JLabel(sDatasetElements.split(";")[0], aLabel.TRAILING); //Makes a JLabel at an array place
aLabel[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aLabel[i], gbConstraint); //Adds a JLabel to the JPanel
//Creation of Elements of type TextField
if(sDatasetElements.split(";")[3].equals("Textfield"))
gbConstraint.gridx = 0; //X position in layout (Label)
gbConstraint.gridy = i; //Y position in layout (Label)
aTextfieldLabel[i] = new JLabel(sDatasetElements.split(";")[0], aTextfieldLabel[i].TRAILING); //Makes a JTextfield at an array place
aTextfieldLabel[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aTextfieldLabel[i], gbConstraint); //Adds a JLabel to the JPanel
gbConstraint.gridx = 1; //X position in layout (Element)
gbConstraint.gridy = i; //Y position in layout (Element)
aTextfield[i] = new JTextField(); //Makes a JTextfield at an array place
aTextfield[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aTextfield[i], gbConstraint); //Adds a JTextField to the JPanel
//Creation of Elements of type Checkbox
if(sDatasetElements.split(";")[3].equals("Checkbox"))
gbConstraint.gridx = 0; //X position in layout (Label)
gbConstraint.gridy = i; //Y position in layout (Label)
aCheckboxLabel[i] = new JLabel(sDatasetElements.split(";")[0], aCheckboxLabel[i].TRAILING); //Makes a JLabel at an array place
aCheckboxLabel[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aCheckboxLabel[i], gbConstraint); //Adds a JLabel to the JPanel
gbConstraint.gridx = 1; //X position in layout (Element)
gbConstraint.gridy = i; //Y position in layout (Element)
aCheckbox[i] = new JCheckBox(); //Makes a JCheckbox at an array place
aCheckbox[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aCheckbox[i], gbConstraint); //Adds a JCheckbox to the JPanel
//Creation of Elements of type Combobox
if(sDatasetElements.split(";")[3].equals("Combobox"))
gbConstraint.gridx = 0; //X position in layout (Label)
gbConstraint.gridy = i; //Y position in layout (Label)
aComboboxLabel[i] = new JLabel(sDatasetElements.split(";")[0], aComboboxLabel[i].TRAILING); // Makes a JLabel at an array place
aComboboxLabel[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aComboboxLabel[i], gbConstraint); //Adds a JLabel to the JPanel
gbConstraint.gridx = 1; //X position in layout (Element)
gbConstraint.gridy = i; //Y position in layout (Element)
aCombobox[i] = new JComboBox(); //Makes a JCombobox at an array place
aCombobox[i].setToolTipText(sDatasetElements.split(";")[1]);
jPanel_Device_Option.add(aCombobox[i], gbConstraint); //Adds a JCombobox to the JPanel
//Get the listvalues from the database option_value is the value that is shown in the list
ResultSet rsValuelist = stmt.executeQuery("select option_value from device_option_value where device_optionid = " + sDatasetElements.split(";")[2] + " and (option_state = " + iOptionState + " or option_state = 40) order by sequence_order");
while(rsValuelist.next())
if(rsValuelist.getString(1) == null)
aCombobox[i].addItem("");
else
aCombobox[i].addItem(rsValuelist.getString(1));
rsValuelist.close();
//Place an empty label at the bottom otherwice the labels are centered in the JPanel
gbConstraint.anchor = GridBagConstraints.PAGE_END;
gbConstraint.weighty = 1.0;
gbConstraint.gridx = 0;
gbConstraint.gridy = aDatasetElements.size() + 1;
jPanel_Device_Option.add(new JLabel(""), gbConstraint); //Adds an empty JLabel to the JPanel
catch (SQLException ex)
ex.printStackTrace();
The is triggered in the init method and the event Item changed of the JCombobox
private void jComboBox_Output_ItemStateChanged(java.awt.event.ItemEvent evt) {                                                  
      //Removed some irrelevant code here
      setOutputSettings();
    }To collect the data that the user has entered in the elements
private void jButton_Collect_User_Data_ActionPerformed(java.awt.event.ActionEvent evt) {                                              
      String sList = "";
      for(int i = 0; i < aDatasetElements.size(); i++)
          String sDatasetElements = aDatasetElements.get(i).toString();
          if(sDatasetElements.split(";")[3].equals("Label"))
              sList = sList + aLabel.getText() + "\n";
if(sDatasetElements.split(";")[3].equals("Textfield"))
sList = sList + aTextfield[i].getText() + "\n";
if(sDatasetElements.split(";")[3].equals("Checkbox"))
sList = sList + aCheckbox[i].isSelected() + "\n";
if(sDatasetElements.split(";")[3].equals("Combobox"))
sList = sList + aCombobox[i].getSelectedItem().toString() + "\n";
JOptionPane.showMessageDialog(null, sList);
I hope ths is helpfull information.
Since I`m totally new to Java it is possible that a different approach is better however this is working for me.
I`m open for any remarks on the code and feel free to give any comments.
Kind Regards Rene