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Jawa Swing multiple layouts in one frame

I'm trying to create Connect 4 game which would look like on this picture:
I've been able to create a gridlayout with 42 buttons and now I need to add Reset button. I believe that I need to combine 2 layouts in one frame but I dont know how to do that and cant find any answer anywhere.
Thank you for your help and time.
public class ApplicationRunner {
public static void main(String[] args) {
new ConnectFour();
}
}
import javax.swing.*;
import java.awt.*;
public class ConnectFour extends JFrame {
private String buttonLbl = "X";
HashMap<String, JButton> buttons;
public ConnectFour() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(600, 600);
setTitle("Connect Four");
setLocationRelativeTo(null);
JButton resetButton = new JButton();
resetButton.setName("reset button");
resetButton.setText("Reset");
for (int i = 6; i > 0; i--) {
for (char c = 'A'; c <= 'G'; c++) {
String cell = "" + c + i;
JButton cellButton = new JButton(" ");
cellButton.setBackground(Color.LIGHT_GRAY);
cellButton.setName("Button" + cell);
add(cellButton);
}
}
GridLayout gl = new GridLayout(6, 7, 0, 0);
setLayout(gl);
setVisible(true);
}
}

One solution is to use two JPanel instances (with each having its own LayoutManager).
Then you add these two JPanel instances to your JFrame.
Example:
public class MyApplication extends JFrame {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
MyApplication app = new MyApplication();
app.setVisible(true);
}
});
}
private MyApplication() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(600, 600);
setTitle("Connect Four");
setLocationRelativeTo(null);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new BoxLayout(buttonPanel, BoxLayout.Y_AXIS));
JButton resetButton = new JButton();
resetButton.setName("reset button");
resetButton.setText("Reset");
resetButton.setAlignmentX(Component.RIGHT_ALIGNMENT);
buttonPanel.add(resetButton);
// add buttonPanel to JFrame
add(buttonPanel, BorderLayout.SOUTH);
JPanel mainPanel = new JPanel(new GridLayout(6, 7, 0, 0));
for (int i = 6; i > 0; i--) {
for (char c = 'A'; c <= 'G'; c++) {
String cell = "" + c + i;
JButton cellButton = new JButton(" ");
cellButton.setBackground(Color.LIGHT_GRAY);
cellButton.setName("Button" + cell);
mainPanel.add(cellButton);
}
}
// add mainPanel to JFrame
add(mainPanel, BorderLayout.CENTER);
setVisible(true);
}
}

JScrollPane "stretching" out the panel that I add to it

I have to make a scrollable list where I can add a panel with 3 labels many times.
I kind of made it work but the first panels are stretched and occupy all the area of the JScrollPane and I can't figure out how to fix this, I tried changing layouts many times but still didn't manage to fix it.
I want the added panel to occupy a fixed size but I can't figure this out. Example in this picture:
https://i.stack.imgur.com/LNznP.png
The one on the left is the one that I get and the one on the right (edited) is how I want it to work.
This is my first day of Swing so the code is very likely a mess, sorry in advance.
Here is the code:
public class MainWindow extends JFrame implements ActionListener{
private JPanel viewportPanel;
private JButton addButton,remButton;
private JScrollPane scrollPane;
private int counter = 0;
private JLabel dateLabel,dateLabel_1,dateLabel_2;
public MainWindow(boolean run) {
//BUTTONS
addButton = new JButton("Add");
addButton.setLocation(521, 11);
addButton.setSize(101, 100);
addButton.addActionListener(this);
remButton = new JButton("Remove");
remButton.setLocation(521, 122);
remButton.setSize(101, 100);
remButton.addActionListener(this);
//SCROLLPANE
scrollPane = new JScrollPane();
scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
scrollPane.setBounds(10, 11, 501, 211);
add(scrollPane);
//PANELS
viewportPanel = new JPanel(new GridLayout(0,1));
scrollPane.setViewportView(viewportPanel);
//FRAME
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 650, 273);
setResizable(false);
//setIconImage(new ImageIcon("epic.png").getImage());
setLayout(null);
if(run) setVisible(true);
add(addButton);
add(remButton);
}
public void actionPerformed(ActionEvent e) {
if(e.getSource() == addButton) {
//LABELS
dateLabel = new JLabel("DATE");
dateLabel.setFont(new Font("Tahoma", Font.BOLD, 28));
dateLabel.setSize(500,500);
dateLabel_1 = new JLabel("LABEL1");
dateLabel_1.setFont(new Font("Tahoma", Font.BOLD, 22));
dateLabel_1.setBounds(10, 45, 481, 30);
dateLabel_2 = new JLabel("LABEL2");
dateLabel_2.setFont(new Font("Tahoma", Font.ITALIC, 22));
dateLabel_2.setBounds(10, 45, 481, 30);
//PANEL WITH ALL THE STUFF
JPanel componentPanel = new JPanel();
componentPanel.setLayout(new GridLayout(3, 1));
componentPanel.setMaximumSize(new Dimension(50,50));
componentPanel.setBorder(BorderFactory.createMatteBorder(1, 1, 1, 1, Color.BLACK));
componentPanel.setBackground(Color.gray);
componentPanel.add(dateLabel);
componentPanel.add(dateLabel_1);
componentPanel.add(dateLabel_2);
viewportPanel.add(componentPanel); //add panel with labels to viewportpanel
counter++;
}
if(e.getSource() == remButton) {
Component[] componentList = viewportPanel.getComponents();
int lastElement = (componentList.length);
viewportPanel.remove(--lastElement);
--counter;
}
viewportPanel.revalidate();
viewportPanel.repaint();
}
}
Some help would be amazing!

First off, never do this:
setLayout(null);
Next, if you want things compressed at the top of a container, then use a layout that does this. such as a BorderLayout with the compressed items placed into a JPanel (perhaps one that uses a GridLayout) that is placed BorderLayout.PAGE_START
Actually, it looks as if your best solution is to us a JList, one that uses a custom renderer that places your time JLabel and two text JLabels into a JPanel and displays this in the list. So let's explore that.
First create a class to hold the data that is displayed by the JList, which looks to be a date and two lines of text:
public class ListItem {
private LocalDate date;
private String text1;
private String text2;
public ListItem(LocalDate date, String text1, String text2) {
super();
this.date = date;
this.text1 = text1;
this.text2 = text2;
}
public LocalDate getDate() {
return date;
}
public String getText1() {
return text1;
}
public String getText2() {
return text2;
}
}
Then let's create a renderer that a JList can use to display the above information in a JPanel. This is more complicated and requires that the class create a JPanel that places the labels where we want them, perhaps using a GridLayout with 1 column and 3 rows, plus some gaps between the rows: setLayout(new GridLayout(3, 1, 2 * gap, 2 * gap));. The class must implement the ListCellRenderer<T> interface which has one method: public Component getListCellRendererComponent(...). Java will pass in the paramters into this method, including a ListItem value, and we will use that value to fill in the JLabels that we add into this JPanel. Edited to highlight selected items.
import java.awt.*;
import java.time.format.DateTimeFormatter;
import javax.swing.*;
import javax.swing.border.Border;
#SuppressWarnings("serial")
public class ListItemRenderer extends JPanel implements ListCellRenderer<ListItem> {
private static final Color LIGHT_BLUE = new Color(204, 255, 255);
private static final Color REDDISH_GREY = new Color(205, 126, 121);
private DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("MM/dd/yyyy");
private static final int GAP = 2;
private Border emptyBorder = BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP);
private Border blackBorder = BorderFactory.createLineBorder(Color.BLACK);
private Border redBorder = BorderFactory.createLineBorder(REDDISH_GREY, 2);
private JLabel dateLabel = new JLabel();
private JLabel text1Label = new JLabel();
private JLabel text2Label = new JLabel();
public ListItemRenderer() {
dateLabel.setFont(dateLabel.getFont().deriveFont(Font.BOLD, 14f));
text1Label.setFont(text1Label.getFont().deriveFont(Font.BOLD));
text2Label.setFont(text1Label.getFont().deriveFont(Font.ITALIC));
int gap = 2;
setLayout(new GridLayout(0, 1, 2 * gap, 2 * gap));
setBorder(BorderFactory.createCompoundBorder(emptyBorder, blackBorder));
add(dateLabel);
add(text1Label);
add(text2Label);
}
#Override
public Component getListCellRendererComponent(JList<? extends ListItem> list, ListItem value, int index,
boolean isSelected, boolean cellHasFocus) {
if (value != null) {
String dateText = dateFormatter.format(value.getDate());
dateLabel.setText(dateText);
text1Label.setText(value.getText1());
text2Label.setText(value.getText2());
} else {
dateLabel.setText("");
text1Label.setText("");
text2Label.setText("");
}
if (isSelected ) {
setBackground(LIGHT_BLUE);
setBorder(BorderFactory.createCompoundBorder(emptyBorder, redBorder));
} else {
setBackground(null);
setBorder(BorderFactory.createCompoundBorder(emptyBorder, blackBorder));
}
return this;
}
}
And now the main program that puts this all together, edited to show removing items:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.KeyEvent;
import java.time.LocalDate;
import java.util.Arrays;
import java.util.Random;
import javax.swing.*;
#SuppressWarnings("serial")
public class MainPanel extends JPanel {
DefaultListModel<ListItem> listModel = new DefaultListModel<>();
private JList<ListItem> jList = new JList<>(listModel);
private JScrollPane scrollPane = new JScrollPane(jList);
private JButton addButton = new JButton("Add");
private JButton removeButton = new JButton("Remove");
public MainPanel() {
jList.setPrototypeCellValue(new ListItem(LocalDate.now(),
"This is text 1 for testing. This is text 1 for testing. This is text 1 for testing",
"This is text 2 for testing. This is text 2 for testing. This is text 2 for testing"));
jList.setVisibleRowCount(4);
jList.setCellRenderer(new ListItemRenderer());
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
JPanel buttonPanel = new JPanel(new GridLayout(0, 1, 3, 3));
buttonPanel.add(addButton);
buttonPanel.add(removeButton);
addButton.setMnemonic(KeyEvent.VK_A);
removeButton.setMnemonic(KeyEvent.VK_R);
addButton.addActionListener(e -> addEvent());
removeButton.addActionListener(e -> removeEvent());
JPanel rightPanel = new JPanel();
rightPanel.add(buttonPanel);
int gap = 5;
setBorder(BorderFactory.createEmptyBorder(gap, gap, gap, gap));
setLayout(new BorderLayout());
add(scrollPane);
add(rightPanel, BorderLayout.LINE_END);
}
private void removeEvent() {
int[] selectedIndices = jList.getSelectedIndices();
for (int i = selectedIndices.length - 1; i >= 0; i--) {
listModel.remove(selectedIndices[i]);
}
}
private void addEvent() {
// this adds random stuff to the JList
String text1 = "Some random text: " + randomText();
String text2 = "Some random text: " + randomText();
listModel.addElement(new ListItem(LocalDate.now(), text1, text2));
// TODO: change this so that it adds *real* data to the JList
}
private String randomText() {
Random random = new Random();
StringBuilder builder = new StringBuilder();
for (int i = 0; i < 2 + random.nextInt(3); i++) {
for (int j = 0; j < 3 + random.nextInt(5); j++) {
char c = (char) ('a' + random.nextInt('z' - 'a'));
builder.append(c);
}
builder.append(" ");
}
return builder.toString();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame("GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new MainPanel());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
});
}
}
Output would look like:

Writing a small app for a DnD puzzle and have trouble with a JButton array

After adding an object of class Puzzle to Main everything displays mostly as it should. when I click any of the buttons some indexes of state should swap to the opposite so from true to false or from false to true.
unfortunately button clicking doesn't want to register for any of the buttons from the array yet it does register for a single button that was initialized by itself. How can I fix the problem?
my code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Arrays;
public class Puzzle extends JFrame implements ActionListener
{
int doors = 8;
boolean [] state = new boolean[doors];
JButton [] levers = new JButton[doors];
JButton weird = new JButton("weird lever");
JLabel display = new JLabel();
Puzzle()
{
reset();
this.setSize(new Dimension(1920, 1080));
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
this.setVisible(true);
this.setResizable(false);
this.setLayout(null);
this.add(display);
this.add(weird);
int num = levers.length;
int start = 50;
int size = (1920-(num+1)*start)/num;
char label = 'A';
display.setBounds(size*2, 150, 2000, 300);
display.setFont(new Font("Arial Black", Font.PLAIN, 200));
Display();
for(JButton i : levers)
{
i = new JButton(String.valueOf(label));
label++;
i.setBounds(start, 500, size, size);
start+=(size+50);
i.addActionListener(this);
i.setFont(new Font("Arial black", Font.PLAIN, size/2));
i.setFocusable(false);
this.add(i);
}
weird.setFocusable(false);
weird.setBounds(550, 800, 800, 200);
weird.setFont(new Font("Arial Black", Font.PLAIN, size/2));
weird.addActionListener(this);
}
#Override
public void actionPerformed(ActionEvent e)
{
/*if(e.getSource() == levers[0])
{
state[2] = Swap(state[2]);
Display();
}
if(e.getSource() == levers[1])
{
state[4] = Swap(state[4]);
state[6] = Swap(state[6]);
Display();
}
if(e.getSource() == levers[2])
{
state[2] = Swap(state[2]);
state[3] = Swap(state[3]);
state[6] = Swap(state[6]);
state[7] = Swap(state[7]);
Display();
}
if(e.getSource() == levers[3])
{
state[0] = Swap(state[0]);
state[2] = Swap(state[2]);
state[7] = Swap(state[7]);
Display();
}
if(e.getSource() == levers[4])
{
state[1] = Swap(state[1]);
state[3] = Swap(state[3]);
state[4] = Swap(state[4]);
state[5] = Swap(state[5]);
Display();
}
if(e.getSource() == levers[5])
{
state[0] = Swap(state[0]);
state[2] = Swap(state[2]);
state[6] = Swap(state[6]);
Display();
}
if(e.getSource() == levers[6])
{
state[1] = Swap(state[1]);
state[5] = Swap(state[5]);
Display();
}
if(e.getSource() == levers[7])
{
state[1] = Swap(state[1]);
state[2] = Swap(state[2]);
state[4] = Swap(state[4]);
state[5] = Swap(state[5]);
Display();
}
*/
if(e.getSource() == levers[0])
{
display.setText("A works");
}
if(e.getSource() == weird)
{
display.setText("test");
}
}
boolean Swap(boolean n)
{
return !n;
}
void Display()
{
StringBuilder toDisplay = new StringBuilder();
for (boolean j : state)
{
if (j)
{
toDisplay.append("| ");
} else
toDisplay.append("_ ");
}
display.setText(toDisplay.toString());
}
void reset ()
{
Arrays.fill(state, true);
}
}```

button clicking doesn't want to register for any of the buttons from the array yet it does register for a single button
System.out.println( levers[0] );
if(e.getSource() == levers[0])
{
display.setText("A works");
}
Add some debug code to your ActionListener and you will see that the value of levers[0] is "null".
for(JButton i : levers)
{
i = new JButton(String.valueOf(label));
label++;
i.setBounds(start, 500, size, size);
start+=(size+50);
i.addActionListener(this);
i.setFont(new Font("Arial black", Font.PLAIN, size/2));
i.setFocusable(false);
this.add(i);
}
You create the button, but you never add the instance of each button to the Array.
for(JButton i : levers)
Why would you use "i" as the variable name. Typically "i" is used as an index. Use a proper variable name, like "button". However, in this case you don't want to use a "for each" loop.
Instead you want a normal for loop so you can index your Array to add each button as you create it:
//for(JButton i : levers)
for (int i = 0; i < doors; i++)
{
JButton button = new JButton(String.valueOf(label));
levers[i] = button;
...
Other issues:
method names should NOT start with an upper case character.
components should be added to the frame BEFORE the frame is made visible.
components should be created on the Event Dispatch Thread (EDT).
Don't use a null layout and setBounds(). Swing was designed to be used with layout managers.
Don't hardcode screen sizes. Instead you can use frame.setExtendedState(JFrame.MAXIMIZED_BOTH);, so it will work for all screen sizes.

Introduction
Your code was too complex for me to understand. I like simple code. Short methods and simple classes.
Here's the GUI I came up with.
Here's the GUI after I clicked a couple of letter JButtons
Explanation
Oracle has a nifty tutorial, Creating a GUI With JFC/Swing, which will show you how to create a Swing GUI. Skip the Netbeans section.
Your code was missing a main method, so I added one. I started the Swing application with a call to the SwingUtilities invokeLater method. This method ensures that the Swing components are created and executed on the Event Dispatch Thread.
The first thing I did was create a PuzzleModel class to hold the boolean array. It's a good idea to separate your model from your view and controller classes. This pattern is the model / view / controller (MVC) pattern.
A Swing JFrame can contain many JPanels. I created a segment JPanel to hold a JLabel and a JButton aligned vertically. I used the GridBagLayout to align the JLabel and JButton. Swing layout managers help you to avoid absolute positioning and the problems that come with absolute positioning.
I created a main JPanel to hold 8 segment JPanels. These JPanels are aligned with a FlowLayout.
As you can see, my JFrame is smaller than yours. You create as small a JFrame as possible. If the user wants to make it bigger, that's what the rectangle in the upper right corner is for.
Swing is meant to be designed from the inside out. You don't specify a JFrame size and try to make the components fit. You create the components and let Swing determine the size of the JFrame. If you want the JFrame I created to be bigger, increase the font sizes. Hint: A fraction or multiple of 72 points looks better on most displays.
I created two ActionListener classes, one for the alphabet JButtons and one for the lever JButton. This makes it easier to focus on the alphabet JButtons. All you have to do in the ActionListener is swap the appropriate isVertical boolean values when each JButton is left-clicked. I just flipped the corresponding boolean as a demonstration.
Code
Here's the complete runnable code.
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Arrays;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class PuzzleGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new PuzzleGUI());
}
private JLabel[] leverLabel;
private final PuzzleModel model;
public PuzzleGUI() {
this.model = new PuzzleModel();
}
#Override
public void run() {
JFrame frame = new JFrame("Weird Lever");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.add(createButtonPanel(), BorderLayout.AFTER_LAST_LINE);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
System.out.println(frame.getSize());
}
private JPanel createMainPanel() {
JPanel panel = new JPanel(new FlowLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
char c = 'A';
boolean[] isVertical = model.getIsVertical();
leverLabel = new JLabel[isVertical.length];
for (int i = 0; i < isVertical.length; i++) {
String labelText = (isVertical[i]) ? "|" : "-";
panel.add(createLeverButtonPanel(labelText, Character.toString(c), i));
c = (char) (((int) c) + 1);
}
return panel;
}
public void updateMainPanel() {
boolean[] isVertical = model.getIsVertical();
for (int i = 0; i < isVertical.length; i++) {
String labelText = (isVertical[i]) ? "|" : "-";
leverLabel[i].setText(labelText);
}
}
private JPanel createLeverButtonPanel(String labelText, String buttonText, int index) {
JPanel panel = new JPanel(new GridBagLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
Font font1 = new Font("Arial Black", Font.PLAIN, 144);
Font font2 = new Font("Arial Black", Font.PLAIN, 72);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
leverLabel[index] = new JLabel(labelText);
leverLabel[index].setFont(font1);
panel.add(leverLabel[index], gbc);
gbc.gridy++;
JButton button = new JButton(buttonText);
button.addActionListener(new AlphabetButtonListener());
button.setFont(font2);
panel.add(button, gbc);
return panel;
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel(new FlowLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
Font font2 = new Font("Arial Black", Font.PLAIN, 48);
JButton button = new JButton("Weird Lever");
button.addActionListener(new LeverButtonListener());
button.setFont(font2);
panel.add(button);
return panel;
}
public class AlphabetButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
JButton button = (JButton) event.getSource();
String text = button.getText();
char c = text.charAt(0);
int index = ((int) c - 'A');
model.swap(index);
updateMainPanel();
}
}
public class LeverButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
// TODO Auto-generated method stub
}
}
public class PuzzleModel {
private boolean[] isVertical;
public PuzzleModel() {
int doors = 8;
this.isVertical = new boolean[doors];
reset();
}
private void reset() {
Arrays.fill(isVertical, true);
}
public void swap(int index) {
isVertical[index] = !isVertical[index];
}
public boolean[] getIsVertical() {
return isVertical;
}
}
}

Runtime Error Java app

Hi guys I built this app to show students how a loop works graphically, that was working although not correctly, but I'll address that in a question later. I'm not sure what I did to the applet but now I get this runtime error. How do I fix this? thanks in advanced!
import java.awt.*;
import java.awt.event.*;
import java.awt.Color;
import javax.swing.JOptionPane;
public class Checkerboard extends Frame implements ActionListener
{
int[] blocksTextField = new int[15];
Panel blocksPanel = new Panel();
TextArea blocksDisplay[] = new TextArea[16];
TextField start = new TextField (3);
TextField stop = new TextField (3);
TextField step = new TextField (3);
//Colors
Color Red = new Color(255, 90, 90);
Color Green = new Color(140, 215, 40);
Color white = new Color(255,255,255);
//textField ints
int inputStart;
int inputStop;
int inputStep;
//Lables
Label custStartLabel = new Label ("Start : ");
Label custStopLabel = new Label ("Stop : ");
Label custStepLabel = new Label ("Step : ");
//Buttons
Button goButton = new Button("Go");
Button clearButton = new Button("Clear");
//panel for input textFields and lables
Panel textInputPanel = new Panel();
//Panel for buttons
Panel buttonPanel = new Panel();
Checkerboard()
{//constructor method
//set the 3 input textFields to 0
inputStart = 0;
inputStop = 0;
inputStep = 0;
//set Layouts for frame and three panels
this.setLayout(new BorderLayout());
//grid layout (row,col,horgap,vertgap)
blocksPanel.setLayout(new GridLayout(4,4,10,10));
textInputPanel.setLayout(new GridLayout(2,3,20,10));
buttonPanel.setLayout(new FlowLayout());
//setEditable()
//setText()
//add components to blocks panel
for (int i = 0; i<16; i++)
{
blocksDisplay[i] = new TextArea(null,3,5,3);
if(i<6)
blocksDisplay[i].setText(" " +i);
else
blocksDisplay[i].setText(" " +i);
blocksDisplay[i].setEditable(false);
// blocksDisplay[i].setBackground(Red);
blocksPanel.add(blocksDisplay[i]);
}
//add componets to panels
//add text fields
textInputPanel.add(start);
textInputPanel.add(stop);
textInputPanel.add(step);
//add lables
textInputPanel.add(custStartLabel);
textInputPanel.add(custStopLabel);
textInputPanel.add(custStepLabel);
//add button to panel
buttonPanel.add(goButton);
buttonPanel.add(clearButton);
//ADD ACTION LISTENRS TO BUTTONS (!IMPORTANT)
goButton.addActionListener(this);
clearButton.addActionListener(this);
add(blocksPanel, BorderLayout.NORTH);
add(textInputPanel, BorderLayout.CENTER);
add(buttonPanel, BorderLayout.SOUTH);
//overridding the windowcClosing() method will allow the user to clisk the Close button
addWindowListener(
new WindowAdapter()
{
public void windowCloseing(WindowEvent e)
{
System.exit(0);
}
}
);
}//end of constructor method
public void actionPerformed(ActionEvent e)
{
//if & else if to see what button clicked and pull user input
if(e.getSource() == goButton) //if go clicked ...
{
System.out.println("go clicked");
try{
String inputStart = start.getText();
int varStart = Integer.parseInt(inputStart);
if (varStart<=0 || varStart>=15 )throw new NumberFormatException();
System.out.println("start = " + varStart);
// roomDisplay[available].setBackground(lightRed);
String inputStop = stop.getText();
int varStop = Integer.parseInt(inputStop);
if (varStop<=0 || varStart>=15 )throw new NumberFormatException();
System.out.println("stop = " + varStop);
String inputStep = step.getText();
int varStep = Integer.parseInt(inputStep);
if (varStep<=0 || varStep>=15 )throw new NumberFormatException();
System.out.println("step = " + varStep);
for (int i = varStart; i<varStop; varStep++)//ADD WHILE LOOP
{
blocksDisplay[i].setBackground(Red);
blocksDisplay[i].setText(" " +i);
}
}
catch (NumberFormatException ex)
{
JOptionPane.showMessageDialog(null, "You must enter a Start, Stop and Step value greater than 0 and less than 15",
"Error",JOptionPane.ERROR_MESSAGE);
}
}
else if(e.getSource() == clearButton ) //else if clear clicked ...
{
System.out.println("clear clicked");
}
//int available = room.bookRoom(smoking.getState());
//if (available > 0)//Rooms is available
}//end action performed method
public static void main(String[]args)
{
Checkerboard frame = new Checkerboard ();
frame.setBounds(50, 100, 300, 410);//changed size to make text feilds full charater size
frame.setTitle("Checkerboarder Array");
frame.setVisible(true);
}//end of main method
}

Make the constructor public.
public Checkerboard() {
...
}
The error appears because the constructor is package-private, e.g. you can't instantiate the class outside it's package.

problems adding arrays of jbutton and jlabel into arrays of jpanel unto a frame

i want to add 10 jlabel and 10 jbutton unto each jpanel. Now there are 10 jpanels which i want to add to a frame, so the jframe should show 100 jlabel, 100 jbutton with 10 jpanels.
My problem is that the frame only shows 10 jlabel and 10 jbutton. i dunno where am wrong.
here is my code
public class MultiPanel extends JFrame {
private JPanel[] panel;
private JLabel[] label;
private JButton[] button;
public MultiPanel() {
panel = new JPanel[10];
label = new JLabel[10];
button = new JButton[10];
for (int i = 0; i < label.length; i++) {
label[i] = new JLabel(String.valueOf(i + 1));
button[i] = new JButton("B");
label[i].setSize(50, 50);
panel[i] = new JPanel();
panel[i].setLayout(new FlowLayout(FlowLayout.CENTER));
panel[i].add(label[i]);
panel[i].add(button[i]);
add(panel[i]);
}
setLayout(new GridLayout(1, 10));
setSize(720, 560);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
MultiPanel m_pnl = new MultiPanel();
}
}

public class MultiPanel extends JFrame {
public MultiPanel() {
int increment = 0;
while(increment < 10){
JPanel toAdd = new JPanel();
for (int i = 0; i < 10; i++) {
JLabel l = new JLabel(String.valueOf(i + 1));
JButton b = new JButton("B");
l.setSize(50, 50);
toAdd.setLayout(new FlowLayout(FlowLayout.CENTER));
toAdd.add(l);
toAdd.add(b);
}
add(toAdd);
increment++;
}
setLayout(new GridLayout(1, 10));
setSize(720, 560);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
MultiPanel m_pnl = new MultiPanel();
}
}
Your logic was faulty... Try this. You have an outer whileloop that will create 10 JPanels like you want. The inner for loop adds 10 JLabels and JButtons to each JPanellike you want. Then you just add all ten JPanels to the main JPanel which is slapped on the JFrame. I have compiled and run this and it works
Before you were only adding one label and button to each panel. You had 10 panels each with 1 button and one label