从Java中的另一个类将JLabel放在JScrollPane上

Question

I am making family tree and this is my problem. I have screens NewFamilyTree.java and NewPerson.java .

NewFamilyTree.java:

public class NewFamilyTree {
...
 private void initialize() {
    frame = new JFrame();
    frame.setTitle("New family tree");
    frame.setBounds(100, 100, 906, 569);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
...
    JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
    frame.getContentPane().add(tabbedPane, BorderLayout.CENTER);

    JScrollPane scrollPane = new JScrollPane();
    tabbedPane.addTab("Tree", null, scrollPane, null);

    panel_1 = new JPanel();
    scrollPane.setViewportView(panel_1);
    panel_1.setLayout(new MigLayout("", "[][][][][][][][]", "[][][][][][]"));

NewPerson.java:

public class NewPerson{

...

buttonAdd = new JButton("Add");
        buttonAdd.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {

                String names = textFieldNames.getText();
                String dateBirth = textFieldDateOfBirth.getText();
                String bio = textAreaBio.getText();

                Data newData = new Data(names, dateBirth, bio, fileID);

               //code that puts new label on scrollpane from NewFamilyTree.java
            }
        });
        buttonAdd.setBackground(new Color(30, 144, 255));
        frame.getContentPane().add(buttonAdd, "cell 2 6,grow");
    }

I need to put new JLabel from class NewPerson , by pressing on button Add , on the JScrollPane of NewFamilytree.java . Hope someone can help, I searched a lot and couldn't help myself.

EDIT: After the answer from @mjr.

I added public JPanel panel_1; in NewFamilyTree . In Add action performed I added:

JLabel lblHomer = new JLabel("Homer");
                lblHomer.setIcon(new ImageIcon("C:\\Users\\Tinmar\\Desktop\\HomerSimpson3.gif"));
                panel_1.add(lblHomer, "cell 7 5");

No errors, but - nothing happens after I press the add button. I also added NewPerson EXTENDS NewFamilyTree , ofc .

Answer 1

1. NewPerson doesn't need extend from NewFamilyTree , it's not adding any functionality to the class
2. Instead of using a JFrame in NewPerson , consider using a modal JDialog instead. See How to Make Dialogs for more details
3. Limit the exposure of components between classes. There is no reason why NewFamilyTree should be able to access the "window" been used by NewPerson . There's no reason why NewPerson should be adding anything to NewFamilyTree
4. Don't mix heavy weight components (like java.awt.Button ) with light weight components, this can cause no end of issues...

You need to change the way you think of things. Instead of trying to make the NewPerson update the UI of the NewFamilyTree , have NewPerson gather the details from the user and pass this information back to NewFamilyTree so it can use it...

For example...

JButton newPersonButton = new JButton("New Person");
newPersonButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent arg0) {
        Data data = NewPerson.createPerson(frame);
        if (data != null) {
            JLabel lblHomer = new JLabel(data.names);
            panel_1.add(lblHomer, "cell 7 5");
            panel_1.revalidate();
        }
    }
});

This basically uses a static method createPerson which passes back a instance of Data (or null if the user cancelled the operation), which NewFamilyTree can then use. It decouples the code, as NewPerson is not relient on anything from NewFamilyTree and NewFamilyTree maintains control. This clearly defines the areas of responsibility between the two classes, it also means that NewPerson could be called from anywhere...

The createPerson method looks, something like, this...

public static Data createPerson(Component comp) {
    NewPerson newPerson = new NewPerson();
    Window win = SwingUtilities.getWindowAncestor(comp);
    JDialog dialog = null;
    if (win instanceof Frame) {
        dialog = new JDialog((Frame) win, "New person", true);
    } else if (win instanceof Dialog) {
        dialog = new JDialog((Dialog) win, "New person", true);
    } else {
        dialog = new JDialog((Frame) null, "New person", true);
    }
    newPerson.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            Object source = e.getSource();
            if (source instanceof Component) {
                Window win = SwingUtilities.getWindowAncestor((Component) source);
                win.dispose();
            }
        }
    });
    dialog.add(newPerson);
    dialog.setVisible(true);

    return newPerson.getData();
}

It basically creates and instance of JDialog , shows it to the user and waits until the NewPerson class triggers an ActionEvent , which it uses to dispose of the dialog. It then asks the instance of NewPerson for the data...

And because there's a whole bunch of functionality I've not talked about, here's a fully runnable example...

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dialog;
import java.awt.EventQueue;
import java.awt.Frame;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

import net.miginfocom.swing.MigLayout;

public class NewFamilyTree {

    private JFrame frame;
    private JPanel panel_1;
    private JScrollPane scrollPane;
    private JTabbedPane tabbedPane;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    NewFamilyTree window = new NewFamilyTree();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

        });
    }

    /**
     * Create the application.
     */
    public NewFamilyTree() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setTitle("New family tree");
        frame.getContentPane().setBackground(new Color(135, 206, 250));
        frame.setBounds(100, 100, 906, 569);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        panel.setBackground(new Color(30, 144, 255));
        frame.getContentPane().add(panel, BorderLayout.EAST);
        panel.setLayout(new MigLayout("", "[]", "[][][][][][][][]"));

        JButton newPersonButton = new JButton("New Person");
        newPersonButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                Data data = NewPerson.createPerson(frame);
                if (data != null) {
                    JLabel lblHomer = new JLabel(data.names);
//                    lblHomer.setIcon(new ImageIcon("C:\\Users\\Tinmar\\Desktop\\HomerSimpson3.gif"));
                    panel_1.add(lblHomer, "cell 7 5");
                    panel_1.revalidate();
                }
            }
        });
        panel.add(newPersonButton, "cell 0 5");

        JButton btnNewButton_1 = new JButton("New button");
        panel.add(btnNewButton_1, "cell 0 6");

        tabbedPane = new JTabbedPane(JTabbedPane.TOP);
        frame.getContentPane().add(tabbedPane, BorderLayout.CENTER);

        scrollPane = new JScrollPane();
        tabbedPane.addTab("Tree", null, scrollPane, null);

        panel_1 = new JPanel();
        scrollPane.setViewportView(panel_1);
        panel_1.setLayout(new MigLayout("", "[][][][][][][][]", "[][][][][][]"));

//        JLabel lblHomer = new JLabel("Homer");
//        lblHomer.setIcon(new ImageIcon("C:\\Users\\Tinmar\\Desktop\\HomerSimpson3.gif"));
//        panel_1.add(lblHomer, "cell 7 5");
        JScrollPane scrollPane_1 = new JScrollPane();
        tabbedPane.addTab("Info", null, scrollPane_1, null);

        frame.repaint();

    }
//
//    /**
//     * Launch the application.
//     */
//    public static void main(String[] args) {
//        EventQueue.invokeLater(new Runnable() {
//            public void run() {
//                try {
//                    NewPerson window = new NewPerson();
//                    window.frame.setVisible(true);
//                } catch (Exception e) {
//                    e.printStackTrace();
//                }
//            }
//        });
//    }

    public static class NewPerson extends JPanel {

        private JTextField textFieldNames;
        private JButton selectPictureButton;
        private JLabel labelDateOfBirth;
        private JTextField textFieldDateOfBirth;
        private JLabel labelShortBio;
        private JTextArea textAreaBio;
        private JLabel labelSelectPicture;
        private JButton buttonAdd;
        private String fileID;

        private Data data;

        /**
         * Create the application.
         */
        private NewPerson() {
            initialize();
        }

        public static Data createPerson(Component comp) {
            NewPerson newPerson = new NewPerson();
            Window win = SwingUtilities.getWindowAncestor(comp);
            JDialog dialog = null;
            if (win instanceof Frame) {
                dialog = new JDialog((Frame) win, "New person", true);
            } else if (win instanceof Dialog) {
                dialog = new JDialog((Dialog) win, "New person", true);
            } else {
                dialog = new JDialog((Frame) null, "New person", true);
            }
            newPerson.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    Object source = e.getSource();
                    if (source instanceof Component) {
                        Window win = SwingUtilities.getWindowAncestor((Component) source);
                        win.dispose();
                    }
                }
            });
            dialog.add(newPerson);
            dialog.pack();
            dialog.setLocationRelativeTo(comp);
            dialog.setVisible(true);

            return newPerson.getData();
        }

        public void addActionListener(ActionListener listener) {
            listenerList.add(ActionListener.class, listener);
        }

        protected void fireActionPerformed() {
            ActionListener[] listeners = listenerList.getListeners(ActionListener.class);
            if (listeners != null && listeners.length > 0) {
                ActionEvent evt = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, "created");
                for (ActionListener listener : listeners) {
                    listener.actionPerformed(evt);
                }
            }
        }

        public Data getData() {
            return data;
        }

        /**
         * Initialize the contents of the frame.
         */
        private void initialize() {
            setBackground(new Color(135, 206, 250));
            setLayout(new MigLayout("", "[][][grow]", "[][][][grow][][][]"));

            JLabel labelNames = new JLabel("Name and Surname:");
            add(labelNames, "cell 1 1,alignx trailing");

            textFieldNames = new JTextField();
            add(textFieldNames, "cell 2 1,growx");
            textFieldNames.setColumns(10);

            labelDateOfBirth = new JLabel("Date of birth:");
            add(labelDateOfBirth, "cell 1 2,alignx center,aligny center");

            textFieldDateOfBirth = new JTextField();
            add(textFieldDateOfBirth, "cell 2 2,growx");
            textFieldDateOfBirth.setColumns(10);

            labelShortBio = new JLabel("Bio:");
            add(labelShortBio, "cell 1 3,alignx center,aligny center");

            textAreaBio = new JTextArea();
            add(textAreaBio, "cell 2 3,grow");

            labelSelectPicture = new JLabel("Select picture:");
            add(labelSelectPicture, "cell 1 4,alignx center,aligny center");

            selectPictureButton = new JButton("...");
            selectPictureButton.setBackground(new Color(30, 144, 255));
            selectPictureButton.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent arg0) {

                    JFileChooser chooser = new JFileChooser(new File(System.getProperty("user.home") + "\\Desktop"));

                    chooser.setDialogTitle("Select Location");
                    chooser.setFileSelectionMode(JFileChooser.APPROVE_OPTION);
                    chooser.setAcceptAllFileFilterUsed(false);

                    if (chooser.showSaveDialog(null) == JFileChooser.APPROVE_OPTION) {
                        fileID = chooser.getSelectedFile().getPath();
                        // txtField.setText(fileID);
                    }

                }
            });
            add(selectPictureButton, "cell 2 4");

            buttonAdd = new JButton("Add");
            buttonAdd.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent arg0) {

                    String names = textFieldNames.getText();
                    String dateBirth = textFieldDateOfBirth.getText();
                    String bio = textAreaBio.getText();

                    data = new Data(names, dateBirth, bio, fileID);
                    fireActionPerformed();
                }
            });
            buttonAdd.setBackground(new Color(30, 144, 255));
            add(buttonAdd, "cell 2 6,grow");
        }

    }

    public static class Data {

        private final String names;
        private final String dateBirth;
        private final String bio;
        private final String fileID;

        private Data(String names, String dateBirth, String bio, String fileID) {
            this.names = names;
            this.dateBirth = dateBirth;
            this.bio = bio;
            this.fileID = fileID;
        }

    }

}

• Don't rely on static to provide functionality across classes. If you HAVE to have something from another class, pass it as a reference. static is not your friend and you should be careful and wary of it's use
• Don't expose the fields of your class without very good reason, rely on interface s to allow classes to provide or get information. This limits what other classes can do.
• Separate and isolate responsibility
• Take a look at How to Use Trees

Answer 2

The same way that NewFamilyTree's frame is accessible in NewPerson when you add the button to it, the scrollPane must also be accessible in NewPerson, if you want to add a label from that class. So just do the same thing with scrollPane as what you did with frame to be able to use it in NewPerson.

Answer 3

I assumed that the JScrollPane and addButton are in different frames... although it will work for sure if they are in the same frame. Basically you need to provide getters for the JScrollPane and the JPanel, so that they can be accessed from the NewPerson class. In the action listener of the buttonAdd, you need to increase the preferred size of the panel,, if the labels don't feet in the current size of the panel. The scrollbars will appear automatically when the preferred size of the panel are bigger that the view size of the JScrollPane.

Please see the code below: NewFamilyTree.jva:

package dva.test001;

import java.awt.BorderLayout;
import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;

public class NewFamilyTree {
    private JFrame frame;
    private JScrollPane scrollPane;
    private JPanel panel;

    public NewFamilyTree() {
        initialize();
    }

    private void initialize() {
        frame = new JFrame();
        frame.setTitle("New family tree");
        frame.setBounds(100, 100, 906, 569);
        frame.setLayout(new BorderLayout());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
        frame.getContentPane().add(tabbedPane, BorderLayout.CENTER);
        panel = new JPanel();
        panel.setPreferredSize(new Dimension(700, 300));
        panel.setLayout(null);
        scrollPane = new JScrollPane(panel);
        tabbedPane.addTab("Tree", null, scrollPane, null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        NewFamilyTree ft = new NewFamilyTree();
        NewPerson np = new NewPerson(ft);
    }

    public JFrame getFrame() {
        return frame;
    }

    public JScrollPane getScrollPane() {
        return scrollPane;
    }

    public JPanel getPanel() {
        return panel;
    }
}

NewPerson.java:

package dva.test001;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class NewPerson {
    private NewFamilyTree familyTree;
    private static final int labelHeight = 30;

    public NewPerson(NewFamilyTree familyTree) {
        this.familyTree = familyTree;
        init();
    }

    public void init() {
        JFrame frame = new JFrame();
        frame.setTitle("New Person");
        frame.setBounds(100, 500, 906, 100);

        JButton buttonAdd = new JButton("Add");
        buttonAdd.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {

                String names = "names"; //textFieldNames.getText();
                String dateBirth = "date"; //textFieldDateOfBirth.getText();
                String bio = "bio"; //textAreaBio.getText();

                //Data newData = new Data(names, dateBirth, bio, fileID);

               //code that puts new label on scrollpane from NewFamilyTree.java
                JLabel lbl = new JLabel(names);
                int top = familyTree.getPanel().getComponentCount() * labelHeight;
                if(top + labelHeight > familyTree.getPanel().getHeight()) {
                    familyTree.getPanel().setPreferredSize(new Dimension(familyTree.getPanel().getWidth(), top + labelHeight));
                    familyTree.getScrollPane().revalidate();
                }
                familyTree.getPanel().add(lbl);
                lbl.setBounds(10, top, 100, labelHeight);
            }
        });
        buttonAdd.setBackground(new Color(30, 144, 255));
        frame.getContentPane().add(buttonAdd);
        frame.setVisible(true);
    }
}