add scrollpane to jpanel when the panel is full (java)

Question

I am working on java swing application and I am adding components dynamically in a JPanel. I want to set a JScrollPane on this panel and only if the panel is full we can see this scrollpane.

How can I do it on this :

 package add_button;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.LineBorder;

public class MyExample 
{
    // Field members
    static JPanel panel = new JPanel();
    static Integer indexer = 1;
    static List<JLabel> listOfLabels = new ArrayList<JLabel>();
    static List<JTextField> listOfTextFields = new ArrayList<JTextField>();

    public static void main(String[] args)
    {       
        // Construct frame
        JFrame frame = new JFrame();
        frame.setLayout(new GridBagLayout());
        frame.setPreferredSize(new Dimension(990, 990));
        frame.setTitle("My Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Frame constraints
        GridBagConstraints frameConstraints = new GridBagConstraints();

        // Construct button
        JButton addButton = new JButton("Add");
        addButton.addActionListener(new ButtonListener());

        // Add button to frame
        frameConstraints.gridx = 0;
        frameConstraints.gridy = 0;
        frame.add(addButton, frameConstraints);

        // Construct panel
        panel.setPreferredSize(new Dimension(600, 600));
        panel.setLayout(new GridBagLayout());
        panel.setBorder(LineBorder.createBlackLineBorder());

        // Add panel to frame
        frameConstraints.gridx = 0;
        frameConstraints.gridy = 1;
        frameConstraints.weighty = 1;
        frame.add(panel, frameConstraints);

        // Pack frame
        frame.pack();

        // Make frame visible
        frame.setVisible(true);
    }

    static class ButtonListener implements ActionListener
    {
        @Override
        public void actionPerformed(ActionEvent arg0) 
        {       
            // Clear panel
            panel.removeAll();

            // Create label and text field
            JTextField jTextField = new JTextField();
            jTextField.setSize(100, 200);
            listOfTextFields.add(jTextField);
            listOfLabels.add(new JLabel("Label " + indexer));

            // Create constraints
            GridBagConstraints textFieldConstraints = new GridBagConstraints();
            GridBagConstraints labelConstraints = new GridBagConstraints();

            // Add labels and text fields
            for(int i = 0; i < indexer; i++)
            {
                // Text field constraints
                textFieldConstraints.gridx = 1;
                textFieldConstraints.fill = GridBagConstraints.HORIZONTAL;
                textFieldConstraints.weightx = 0.5;
                textFieldConstraints.insets = new Insets(10, 10, 10, 10);
                textFieldConstraints.gridy = i;

                // Label constraints
                labelConstraints.gridx = 0;
                labelConstraints.gridy = i;
                labelConstraints.insets = new Insets(10, 10, 10, 10);

                // Add them to panel
                panel.add(listOfLabels.get(i), labelConstraints);
                panel.add(listOfTextFields.get(i), textFieldConstraints);
            }

            // Align components top-to-bottom
            GridBagConstraints c = new GridBagConstraints();
            c.gridx = 0;
            c.gridy = indexer;
            c.weighty = 1;
            panel.add(new JLabel(), c);

            // Increment indexer
            indexer++;
            panel.updateUI();
        }
    }
}

Solution 1

Here you go

    // Construct panel
    //panel.setPreferredSize(new Dimension(600, 600)); // No need for panel as it will get added to scrollpane
    panel.setLayout(new GridBagLayout());
    panel.setBorder(LineBorder.createBlackLineBorder());


    JScrollPane scrollPane = new JScrollPane(panel,   ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    scrollPane.setPreferredSize(new Dimension(600, 600));
    // Add panel to frame
    frameConstraints.gridx = 0;
    frameConstraints.gridy = 1;
    frameConstraints.weighty = 1;
    frame.add(scrollPane, frameConstraints); // add acrollpane to frame

I have created a JScrollPane, added panel as its component and then added scrollPane to frame

Here

Solution 2

Add panel into JScrollPane, but create ScrollPane by this constractor

JScrollPane scrollPane = new JScrollPane(panel, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);

ScrollBars became visible only when panel size became bigger then parent component size.

Solution 3

On you jscrollpane you need to set vertical and horizontal bar schemes. for example

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;


public class windows_test {
    JFrame login = null;
    JFrame inner_frame = null;

    public windows_test() {
        login = new JFrame();
        login.setBounds(10, 10, 300, 300);
        login.setLayout(new BorderLayout());

        JPanel temp_panel = new JPanel();

        temp_panel.add(new JTextArea("asd fsj   adhf jsad kjfh sa dj kfh j sak ds fda f hsa kj d hf ks ad hf kjs ad h fk js ad h fjs da hf k j sahd kjfsh d jk fhs ad"));

        login.setVisible(true);
        JScrollPane scroll_pane = new JScrollPane(temp_panel);
        scroll_pane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED); //SETTING SCHEME FOR HORIZONTAL BAR
        scroll_pane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        login.add(scroll_pane);
    }
}

hope it will help you. if you are facing any problem then you can ask i will try to solve it.

Solution 4

frame = new JFrame();
frame.setBounds(0, 0, 820, 950);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JPanel panel = new JPanel();
panel.setLayout(null);

final JScrollPane scrollPanel = new JScrollPane(
    panel,
    ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
    ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS
);
scrollPanel.setBounds(0, 0, 800, 900);
panel.setBounds(0, 0, 1920, 1080);
panel.setPreferredSize(new Dimension(1920, 1080));
frame.getContentPane().add(scrollPanel);

This code will work in general to add JScrollPane to JPanel. Adjust bounds of frame, panel and scrollpane according to your requirements but ensure that the bounds of JScrollPane are within the bounds of the frame otherwise the scrollpane will not be visible.

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