Develop Reference

how to add a specific number of buttons created in a loop

i have a problem with adding a specific number of buttons from my for-loop to my JPanel, i know how to add all oof them, but i want to add only 1-10 (i havent decided yet, lets go with 10).'
this is my class where i just declare what objects i want to have.
private static int cID;
private static Deck[] card;
static ArrayList<JButton> buttonList = new ArrayList<JButton>();
private JFrame f;
private JPanel p1;
private JButton button;
public boolean isEmpty() {
return cID == 0;
}
public static void main(String[] args) {
CustomDecks c = new CustomDecks();
c.deckCreator();
}```
this is my for-loop where i create 420 buttons and give them names "card" + i where i is 0 - 419, yet when i try to add card0 to my panel, it fails, why?
private void deckCreator() {
card = new Deck[25];
new ArrayList<Cards> (cSet.cards);
for(int i = 0; i < 420; i++) {
button = new JButton();
buttonList.add(button);
button.setName("card" + i);
f.add(button);
p1.add(card0);
}
f.add(p1);
f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
f.setVisible(true);
f.setExtendedState(Frame.MAXIMIZED_BOTH);
f.setUndecorated(true);
}
}
}

I'm not sure you can create a JPanel large enough to hold 420 JButtons.
Here's an example of a JButton GUI.
[
Generally, you create an application model and view separately. The model is made up of one or more plain Java classes. The view reads from the application model but doesn't update the model.
Your controller classes (ActionListener classes) update the application model and update / repaint the view.
This pattern is called the model / view / controller (MVC) pattern.
You can see in the example code below that the model is created in the view class constructor. Generally, you create the application model first, then you create the application view.
And here's the complete runnable code.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
public class JButtonScrollGUI {
private JFrame frame;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
new JButtonScrollGUI();
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
private String[] greekAlphabet;
public JButtonScrollGUI() {
this.greekAlphabet = new String[] { "alpha", "beta", "gamma", "epsilon", "zeta" };
initialize();
}
private void initialize() {
frame = new JFrame();
frame.setTitle("Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createScrollPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createScrollPanel() {
JPanel panel = new JPanel(new BorderLayout());
JPanel innerPanel = createButtonPanel();
Dimension d = innerPanel.getPreferredSize();
d.width += 50;
d.height /= 2;
panel.setPreferredSize(d);
JScrollPane scrollPane = new JScrollPane(innerPanel);
panel.add(scrollPane, BorderLayout.CENTER);
return panel;
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel(new GridLayout(0, 3, 10, 10));
panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
for (int i = 0; i < 20; i++) {
JButton button1 = new JButton("Previous " + i);
panel.add(button1);
JComboBox<String> selectorBox = new JComboBox<>(greekAlphabet);
panel.add(selectorBox);
JButton button2 = new JButton("Next " + i);
button2.setPreferredSize(button1.getPreferredSize());
panel.add(button2);
}
return panel;
}
}

Adding new comboboxes Java

I have a problem with Swing interface on java. Explaination: I have a Combobox with 1, 2, 3, 4, 5 items. When an exact item is selected I need to create some more comboboxes the number of which depends on the selected item. So, if number 5 is selected, 5 more comboboxes must appear in the frame. I used ActionListener but it did not work properly. However, the same code but outside Actionlistener works well. What a problem can it be?
public class FrameClass extends JFrame {
JPanel panel;
JComboBox box;
String[] s = {"1", "2", "3", "4", "5"};
String[] s1 = {"0", "1", "2", "3", "4", "5"};
public FrameClass() {
panel = new JPanel();
box = new JComboBox(s);
JComboBox adults = new JComboBox(s);
JComboBox children = new JComboBox(s1);
panel.add(box, BorderLayout.CENTER);
box.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
for(int i = 0; i <= box.getSelectedIndex(); i++) {
panel.add(adults, BorderLayout.WEST);
panel.add(children, BorderLayout.WEST);
}
}
});
add(panel);
}
}
public class MainClass {
public static void main(String[] args) {
JFrame frame = new FrameClass();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setExtendedState(Frame.MAXIMIZED_BOTH);
frame.getContentPane().setBackground(Color.WHITE);
frame.setVisible(true);
}
}

The problem that you don't inform the layout manager about new elements in your panel.
Here is the correct variant of your action listener:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;
public class FrameClass extends JFrame {
JPanel panel;
JComboBox<String> box;
String[] s = {"1", "2", "3", "4", "5"};
String[] s1 = {"0", "1", "2", "3", "4", "5"};
public FrameClass() {
panel = new JPanel();
box = new JComboBox(s);
JComboBox[] adults = new JComboBox[5];
JComboBox[] children = new JComboBox[5];
for (int i = 0; i < 5; i++) {
adults[i] = new JComboBox<>(s);
children[i] = new JComboBox<>(s1);
}
panel.add(box, BorderLayout.CENTER);
JPanel nested = new JPanel();
add(nested, BorderLayout.EAST);
box.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
nested.removeAll();
nested.setLayout(new GridLayout(box.getSelectedIndex() + 1, 2));
for (int i = 0; i <= box.getSelectedIndex(); i++) {
nested.add(adults[i]);
nested.add(children[i]);
}
getContentPane().revalidate();
getContentPane().repaint();
pack();
}
});
add(panel);
}
public static void main(String[] args) {
JFrame frame = new FrameClass();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.pack();
frame.getContentPane().setBackground(Color.WHITE);
frame.setLocationRelativeTo(null); // center the window
frame.setVisible(true);
}
}

Previous function of CardLayout not working?

The next function of my cardlayout is working properly, but previous isnt. As far as I'm concerned, just having "layout.previous(_);" in the actionPerformed method body in my makePanel() method should work, but when I run my program and click the prev button, nothing happens. What am I doing wrong? –
import java.awt.*;
import javax.swing.*;
import java.util.*;
import java.awt.event.*;
public class Temp
{
public static void main (String[] args)
{
new MakeAQuiz();
}
static class MakeAQuiz
{
private JPanel start, base, fields, buttonz, question;
private String [] labels = {"Enter your question: ", "Answer 1: ", "Answer 2: ", "Answer 3: ", "Answer 4: "};
private JButton [] buttons = {new JButton("<<Go back"), new JButton("I'm done"), new JButton("Next>>")};
private JFrame makeFrame;
public MakeAQuiz()
{
start = new JPanel(new CardLayout());
start.add(makePanel(),"1");
makeFrame = new JFrame();
makeFrame.setSize(500,600);
makeFrame.add(start);
makeFrame.setVisible(true);
makeFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public JFrame getJFrame()
{
return makeFrame;
}
public JPanel makePanel()
{
question = new JPanel(new FlowLayout());
fields = new JPanel(new GridBagLayout());
buttonz = new JPanel(new FlowLayout());
base = new JPanel(new BorderLayout());
GridBagConstraints c = new GridBagConstraints();
c.weighty=0.5; //adds padding between the fields vertically
for (int i = 1; i<5; i++)
{
c.gridy++; //puts each field in a seperate line/row
JLabel label = new JLabel(labels[i]);
// c.fill = GridBagConstraints.HORIZONTAL;
fields.add(label,c);
JTextField textField = new JTextField(20);
fields.add(textField,c);
}
final CardLayout layout = (CardLayout)start.getLayout();
buttons[1].addActionListener(new ActionListener() {
// #Override
public void actionPerformed(ActionEvent e) {
buttons[0].setEnabled(false);
buttons[2].setEnabled(false);
// for(Component comp : cardPanel.getComponents()) {
// if(comp instanceof Page) {
// Page page = (Page)comp;
// page.printData();
// }
// }
}
});
buttons[2].addActionListener(new ActionListener()
{
// #Override
public void actionPerformed(ActionEvent e)
{
start.add(makePanel(), String.valueOf(start.getComponentCount() + 1));
layout.next(start);
}
});
buttons[0].addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
layout.previous(start);
}
});
buttonz.add(buttons[0]);
buttonz.add(buttons[1]);
buttonz.add(buttons[2]);
JLabel l = new JLabel(labels[0]);
JTextField t = new JTextField(30);
question.add(l);
question.add(t);
base.add(question,BorderLayout.NORTH);
base.add(buttonz,BorderLayout.SOUTH);
base.add(fields,BorderLayout.CENTER);
return base;
}
}
}

I have no issue (with your code), once I added some additional components to the start panel.
You will, however, have issues because you've added the buttons to the panel been displayed in the CardLayout.
A better solution would be to put the buttons at the bottom of the main screen and separate it from the cards.
You would need to maintain some kind of counter or reference to the current page, as CardLayout doesn't provide any way to obtain a reference to the current card. This would allow you to enabled/disable the next/previous buttons approritaly...
Updated with runnable example...
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MakeAQuiz {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
new MakeAQuiz();
}
});
}
private JPanel start, base, fields, buttonz, question;
private String[] labels = {"Enter your question: ", "Answer 1: ", "Answer 2: ", "Answer 3: ", "Answer 4: "};
private JButton[] buttons = {new JButton("<<Go back"), new JButton("I'm done"), new JButton("Next>>")};
private JFrame makeFrame;
public MakeAQuiz() {
start = new JPanel(new CardLayout());
start.add(makePanel(), "1");
makeFrame = new JFrame();
makeFrame.add(start);
buttonz = new JPanel(new FlowLayout());
final CardLayout layout = (CardLayout) start.getLayout();
buttons[1].addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
buttons[0].setEnabled(false);
buttons[2].setEnabled(false);
}
});
buttons[2].addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int count = start.getComponentCount();
start.add(new JLabel(Integer.toString(count), JLabel.CENTER), Integer.toString(count));
layout.next(start);
}
});
buttons[0].addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
layout.previous(start);
}
});
buttonz.add(buttons[0]);
buttonz.add(buttons[1]);
buttonz.add(buttons[2]);
makeFrame.add(buttonz, BorderLayout.SOUTH);
makeFrame.pack();
makeFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
makeFrame.setVisible(true);
}
public JFrame getJFrame() {
return makeFrame;
}
public JPanel makePanel() {
question = new JPanel(new FlowLayout());
fields = new JPanel(new GridBagLayout());
base = new JPanel(new BorderLayout());
GridBagConstraints c = new GridBagConstraints();
c.weighty = 0.5; //adds padding between the fields vertically
for (int i = 1; i < 5; i++) {
c.gridy++; //puts each field in a seperate line/row
JLabel label = new JLabel(labels[i]);
// c.fill = GridBagConstraints.HORIZONTAL;
fields.add(label, c);
JTextField textField = new JTextField(20);
fields.add(textField, c);
}
JLabel l = new JLabel(labels[0]);
JTextField t = new JTextField(30);
question.add(l);
question.add(t);
base.add(question, BorderLayout.NORTH);
base.add(fields, BorderLayout.CENTER);
return base;
}
}

No. I think its not gonna work that way. Simply clicking the previous button will not bring anything back. You should save your entries somewhere else and load them to corresponding fields when clicking on the previous button.

double click on jlist in netbeans

I want select item in list by mouse. I found this code but it didn't work.
MouseListener mouseListener = new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if (e.getClickCount() == 2) {
int index = list.locationToIndex(e.getPoint());
System.out.println("Double clicked on Item " + index);
}
}
};
list.addMouseListener(mouseListener);

try this code, Sample Application it works fine !!!!!!
import java.awt.BorderLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
public class calc {
public static void main(String args[]) {
String labels[] = { "A", "B", "C", "D", "E", "F", "G", "H" };
JFrame frame = new JFrame("Selecting JList");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JList jlist = new JList(labels);
JScrollPane scrollPane1 = new JScrollPane(jlist);
frame.add(scrollPane1, BorderLayout.CENTER);
MouseListener mouseListener = new MouseAdapter() {
public void mouseClicked(MouseEvent mouseEvent) {
JList theList = (JList) mouseEvent.getSource();
if (mouseEvent.getClickCount() == 2) {
int index = theList.locationToIndex(mouseEvent.getPoint());
if (index >= 0) {
Object o = theList.getModel().getElementAt(index);
System.out.println("Double-clicked on: " + o.toString());
}
}
}
};
jlist.addMouseListener(mouseListener);
frame.setSize(350, 200);
frame.setVisible(true);
}
}

Can't drag to resize JTable columns

Long story short, I'm making a custom Swing component that's basically a JTable with a panel on its side. The table should of course be scrollable and have a table header, but since I only want the header to be above the actual JTable and not above the side panel, I had to pull some tricks to make it work. But that part works fine.
However, in the process I've somehow managed to break the mouse-drag-column-resizing functionality of the JTableHeader. I am completely clueless as to why and what I can do about it.
Below is a minimal working sample to illustrate my problem.
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
import javax.swing.Scrollable;
import javax.swing.table.JTableHeader;
final class FooTable extends JPanel implements Scrollable {
public FooTable() {
initComponents();
}
// Generated by NetBeans IDE
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
java.awt.GridBagConstraints gridBagConstraints;
sidePanel = new javax.swing.JPanel();
table = new javax.swing.JTable();
setLayout(new java.awt.GridBagLayout());
sidePanel.setMinimumSize(new java.awt.Dimension(70, 0));
sidePanel.setPreferredSize(new java.awt.Dimension(70, 0));
sidePanel.setLayout(null);
gridBagConstraints = new java.awt.GridBagConstraints();
gridBagConstraints.gridx = 0;
gridBagConstraints.gridy = 0;
gridBagConstraints.fill = java.awt.GridBagConstraints.BOTH;
gridBagConstraints.anchor = java.awt.GridBagConstraints.NORTHWEST;
gridBagConstraints.weighty = 1.0;
add(sidePanel, gridBagConstraints);
table.setFont(table.getFont().deriveFont(table.getFont().getSize()+1f));
table.setModel(new javax.swing.table.DefaultTableModel(
new Object [][] {
{"1", "A", "I", "-"},
{"2", "B", "II", "--"},
{"3", "C", "III", "---"},
{"4", "D", "IV", "----"},
{"5", "E", "V", "-----"},
{"6", "F", "VI", "------"},
{"7", "G", "VII", "-------"},
{"8", "H", "VIII", "--------"},
{"9", "I", "IX", "---------"},
{"10", "J", "X", "----------"}
},
new String [] {
"Column 1", "Column 2", "Column 3", "Column 4"
}
));
table.setRowHeight(24);
table.setSelectionMode(javax.swing.ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
gridBagConstraints = new java.awt.GridBagConstraints();
gridBagConstraints.gridx = 1;
gridBagConstraints.gridy = 0;
gridBagConstraints.fill = java.awt.GridBagConstraints.BOTH;
gridBagConstraints.anchor = java.awt.GridBagConstraints.NORTHWEST;
gridBagConstraints.weightx = 1.0;
add(table, gridBagConstraints);
}// </editor-fold>
public JScrollPane createScrollView() {
JScrollPane jsp = new JScrollPane(this);
JViewport jvp = new JViewport();
final JTableHeader th = new JTableHeader();
th.setTable(table);
th.setColumnModel(table.getColumnModel());
th.setResizingAllowed(true);
jvp.setView(new JPanel() {
{
setLayout(null);
add(th);
th.setLocation(70, 0);
FooTable.this.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
th.setSize(FooTable.this.getWidth(), th.getPreferredSize().height);
}
});
setPreferredSize(new Dimension(th.getPreferredSize().width, th.getPreferredSize().height));
}
});
jsp.setColumnHeader(jvp);
return jsp;
}
// Variables declaration - do not modify
private javax.swing.JPanel sidePanel;
private javax.swing.JTable table;
// End of variables declaration
//
// Scrollable implementation
//
public Dimension getPreferredScrollableViewportSize() {
Dimension d = new Dimension();
d.width = sidePanel.getPreferredSize().width + table.getPreferredSize().width;
d.height = sidePanel.getPreferredSize().height + table.getPreferredSize().height;
return d;
}
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
return table.getScrollableUnitIncrement(visibleRect, orientation, direction);
}
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
return table.getScrollableBlockIncrement(visibleRect, orientation, direction);
}
public boolean getScrollableTracksViewportWidth() {
return table.getScrollableTracksViewportWidth();
}
public boolean getScrollableTracksViewportHeight() {
return table.getScrollableTracksViewportHeight();
}
//
// Test program
//
public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
FooTable fooTable = new FooTable();
f.add(fooTable.createScrollView());
f.pack();
f.setVisible(true);
}
}

I think what you are missing is also telling the JTable about the JTableHeader. In the method createScrollView try adding the following just before returning:
table.setTableHeader(th);