Creating objects from dynamic JPanels

Question

I have written some code to create JPanels dynamically. I now need a way to capture the data that the user creates in these JPanels. I currently have a "create" button. When fired, I want this button to create an object using the 3 different data types in each panel: name(String), count(int), and a boolean.

I am pretty raw at programming, but the major hurdle I am facing is how to I access dynamic objects that are not named like these panels? I figured out how to add and remove them, but I can't figure out the methods to capture data from the fields in the panes.

Thanks, the code is as follows:

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;


public class MainSnakeGUI {

    public static void main(String[] arg) {
        new MainSnakeGUI();
    }

    public MainSnakeGUI() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception e) {
                    e.printStackTrace();
                }

                //Create the frame
                JFrame frame = new JFrame("Snake Channels");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new SnakePane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class SnakePane extends JPanel {
        public SnakePane() {
            //Create buttons and labels
            JButton btnAdd = new JButton("Add New Snake");
            JButton btnRemove = new JButton("Delete Snake");
            JLabel headerLabel = new JLabel("Create a Split Snake");
            JButton btnCreate = new JButton("Create");
            setLayout(new BorderLayout());
            //Create JPanels
            JPanel buttons = new JPanel(new FlowLayout(FlowLayout.LEFT));
            JPanel header = new JPanel(new FlowLayout(FlowLayout.CENTER));
            JPanel footer = new JPanel(new FlowLayout(FlowLayout.CENTER));
            //add items to JPanels
            buttons.add(btnAdd);
            buttons.add(btnRemove);
            header.add(headerLabel);
            footer.add(btnCreate);
            //add JPanels to window
            add(header, BorderLayout.NORTH);  //sets header at the top of window
            header.setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
            add(buttons, BorderLayout.BEFORE_LINE_BEGINS);  //sets the button to the left of the display pane
            buttons.setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
            add(footer, BorderLayout.AFTER_LAST_LINE);  //sets buttons on the bottom of window
            footer.setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));


            //add panel to hold new frames
            final JPanel content = new JPanel(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.weighty = 1;
            content.add(new JPanel(), gbc);

            //add scroll pane?
            add(new JScrollPane(content));

            //add listener for button
            btnAdd.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    SplitSnakeCreationPane pane = new SplitSnakeCreationPane();  //create a new SnakeCreationPane
                    int insertAt = Math.max(0, content.getComponentCount() - 1);  //insert it at the end of the list
                    GridBagConstraints gbc = new GridBagConstraints();
                    gbc.gridwidth = GridBagConstraints.REMAINDER;
                    gbc.fill = GridBagConstraints.HORIZONTAL;
                    gbc.weightx = 1;
                    content.add(pane, gbc, insertAt);  //add the pane to the window
                    content.revalidate();
                    content.repaint();
                }
            });

            btnRemove.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    int paneCount = content.getComponentCount()-1;  //get count of the pane
                    content.remove(content.getComponent(paneCount-1));  //remove the pane at paneCount
                    content.revalidate();  //update window with changes
                    content.repaint();
                    SplitSnakeCreationPane.snakeCount--;  //update count for snakes
                }
            });

            btnCreate.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    int paneCount = content.getComponentCount()-1;  //get count of the pane
                    for (int i=0; i<paneCount;){

                    }
                }
            });
        }

        //set size of window
        @Override
        public Dimension getPreferredSize() {
            return new Dimension(1200, 400);
        }
    }

    public static class SplitSnakeCreationPane extends JPanel {
        //Count of how many snakes created
        private static int snakeCount = 1;

        public SplitSnakeCreationPane() {

            //creates Snake Panes
            setLayout(new GridLayout(2, 4, 10, 10));
            add(new JLabel("Split Snake " + (snakeCount++) + "."));
            add(new JLabel("Snake Name"));
            add(new JLabel("Channel Count"));
            add(new JLabel(""));
            add(new JLabel(""));
            JTextField snakeName =  new JTextField(30);
            JTextField channelCount = new JTextField("0",3);
            JCheckBox artistSupplied = new JCheckBox("Artist Supplied?");
            add(snakeName); //Snake Name field
            add(channelCount);  //Channel Count field
            add(artistSupplied); //Artist supplied checkbox
            setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
        }
    }
}

Answer 1

Instead of putting those fields as local variables in the constructor, You need use class variables in your SplitSnakeCreationPane and then add a public get method to get the values from those fields. As long as you have those get method, you can use it to get filed value anywhere you need.

see the modified class as follows:

public static class SplitSnakeCreationPane extends JPanel {
        //Count of how many snakes created
        private static int snakeCount = 1;

        private JTextField snakeName = null;
        private JTextField channelCount = null;        
        private JCheckBox artistSupplied = null;

        public SplitSnakeCreationPane() {

            //creates Snake Panes
            setLayout(new GridLayout(2, 4, 10, 10));
            add(new JLabel("Split Snake " + (snakeCount++) + "."));
            add(new JLabel("Snake Name"));
            add(new JLabel("Channel Count"));
            add(new JLabel(""));
            add(new JLabel(""));
            snakeName =  new JTextField(30);
            channelCount = new JTextField("0",3);
            artistSupplied = new JCheckBox("Artist Supplied?");
            add(snakeName); //Snake Name field
            add(channelCount);  //Channel Count field
            add(artistSupplied); //Artist supplied checkbox
            setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
        }

        public String getSnakeName() {
            return snakeName.getText();
        }

        public String getChannelCount() {
            return channelCount.getText();
        }

        public boolean getArtistSupplied() {
            return artistSupplied.isSelected();
        }
    }

Here is the complete code, copy paste and give it a run: result will be printed on the console. hope You can get the idea on how to get those values

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;


public class MainSnakeGUI {

    public static void main(String[] arg) {
        new MainSnakeGUI();
    }

    public MainSnakeGUI() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception e) {
                    e.printStackTrace();
                }

                //Create the frame
                JFrame frame = new JFrame("Snake Channels");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new SnakePane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class SnakePane extends JPanel {


        public SnakePane() {
            //Create buttons and labels
            JButton btnAdd = new JButton("Add New Snake");
            JButton btnRemove = new JButton("Delete Snake");
            JButton show = new JButton("show value");
            JLabel headerLabel = new JLabel("Create a Split Snake");
            JButton btnCreate = new JButton("Create");
            setLayout(new BorderLayout());
            //Create JPanels
            JPanel buttons = new JPanel(new FlowLayout(FlowLayout.LEFT));
            JPanel header = new JPanel(new FlowLayout(FlowLayout.CENTER));
            JPanel footer = new JPanel(new FlowLayout(FlowLayout.CENTER));
            //add items to JPanels
            buttons.add(btnAdd);
            buttons.add(btnRemove);
            buttons.add(show);
            header.add(headerLabel);
            footer.add(btnCreate);
            //add JPanels to window
            add(header, BorderLayout.NORTH);  //sets header at the top of window
            header.setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
            add(buttons, BorderLayout.BEFORE_LINE_BEGINS);  //sets the button to the left of the display pane
            buttons.setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
            add(footer, BorderLayout.AFTER_LAST_LINE);  //sets buttons on the bottom of window
            footer.setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));


            //add panel to hold new frames
            final JPanel content = new JPanel(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.weighty = 1;
            content.add(new JPanel(), gbc);

            //add scroll pane?
            add(new JScrollPane(content));

            //add listener for button
            btnAdd.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    SplitSnakeCreationPane pane = new SplitSnakeCreationPane();  //create a new SnakeCreationPane
                    int insertAt = Math.max(0, content.getComponentCount() - 1);  //insert it at the end of the list
                    GridBagConstraints gbc = new GridBagConstraints();
                    gbc.gridwidth = GridBagConstraints.REMAINDER;
                    gbc.fill = GridBagConstraints.HORIZONTAL;
                    gbc.weightx = 1;
                    content.add(pane, gbc, insertAt);  //add the pane to the window

                    System.out.println(insertAt);
                    content.revalidate();
                    content.repaint();
                }
            });

            btnRemove.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    int paneCount = content.getComponentCount()-1;  //get count of the pane
                    content.remove(content.getComponent(paneCount-1));  //remove the pane at paneCount
                    content.revalidate();  //update window with changes
                    content.repaint();
                    SplitSnakeCreationPane.snakeCount--;  //update count for snakes
                }
            });


            show.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {

                    for(int n=0; n<content.getComponentCount(); n++){

                        if(content.getComponent(n) instanceof SplitSnakeCreationPane){

                            SplitSnakeCreationPane com = (SplitSnakeCreationPane) content.getComponent(n);

                            System.out.println("Sname Name is : " + com.getSnakeName());
                            System.out.println("ChannelCount is : " + com.getChannelCount());
                            System.out.println("ArtistSupplied  is : " + com.getArtistSupplied());
                        }


                    }



                }
            });


            btnCreate.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    int paneCount = content.getComponentCount()-1;  //get count of the pane
                    for (int i=0; i<paneCount;){

                    }
                }
            });
        }

        //set size of window
        @Override
        public Dimension getPreferredSize() {
            return new Dimension(1200, 400);
        }
    }

    public static class SplitSnakeCreationPane extends JPanel {
        //Count of how many snakes created
        private static int snakeCount = 1;

        private JTextField snakeName = null;
        private JTextField channelCount = null;        
        private JCheckBox artistSupplied = null;

        public SplitSnakeCreationPane() {

            //creates Snake Panes
            setLayout(new GridLayout(2, 4, 10, 10));
            add(new JLabel("Split Snake " + (snakeCount++) + "."));
            add(new JLabel("Snake Name"));
            add(new JLabel("Channel Count"));
            add(new JLabel(""));
            add(new JLabel(""));
            snakeName =  new JTextField(30);
            channelCount = new JTextField("0",3);
            artistSupplied = new JCheckBox("Artist Supplied?");
            add(snakeName); //Snake Name field
            add(channelCount);  //Channel Count field
            add(artistSupplied); //Artist supplied checkbox
            setBorder(new CompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(10, 10, 10, 10)));
        }

        public String getSnakeName() {
            return snakeName.getText();
        }

        public String getChannelCount() {
            return channelCount.getText();
        }

        public boolean getArtistSupplied() {
            return artistSupplied.isSelected();
        }
    }
}

Answer 2

The best way to do this is to create your own custom action listener:

public class CustomListener extends ActionListener {

    private List<SplitSnakeCreationPane> allPanes = new ArrayList<SplitSnakeCreationPane>();

    @Override
    public void actionPerformed(ActionEvent e) {
    //Create your pane
    //Add that pane to your 'allPanes' list.
    }

    public List<SplitSnakeCreationPane> getAllPanes(){
        return this.allPanes;
    }

}

Now you create an object of this class and add that to the button:

CustomListener createListener = new CustomListener();
btnCreate.addActionListener(createListener);

Now if you wish to retrieve the panes you added, just call:

List<SplitSnakeCreationPane> allPanes = createListener.getAllPanes();