Develop Reference

java swing remove latest added panel

I am adding panels to a frame with a button click, each panel goes under the last added panel, I achieve that with setBounds, each time incrementing y position. There is a second button, that is supposed to remove the latest panel that I added. It should keep removing panels after every click. I have tried a few solutions but they all failed.
My code:
public class lab3 {
static int y = 50;
static JButton addThread;
static JPanel results;
public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(550, 650);
jFrame.setTitle("Lab3");
jFrame.setVisible(true);
JPanel panelAddThread = new JPanel();
panelAddThread.setLayout(null);
panelAddThread.setBounds(0, 0, 550, 50);
panelAddThread.setBackground(Color.red);
JLabel threadLabel = new JLabel();
threadLabel.setText("Thread count: ");
addThread = new JButton();
addThread.setBounds(300, 0, 25, 25);
addThread.setText("+");
addThread.setBorder(null);
addThread.addActionListener(e -> {
results = new JPanel();
results.setBounds(0, y, 550, 150);
results.setBackground(Color.blue);
results.setLayout(null);
jFrame.add(results);
jFrame.repaint();
y = y+ 150;
});
// Remove
JButton removeThread = new JButton();
removeThread.setBorder(null);
removeThread.setBounds(340, 0, 25, 25);
removeThread.setText("-");
removeThread.addActionListener(e -> {
});
panelAddThread.add(threadLabel);
panelAddThread.add(removeThread);
panelAddThread.add(addThread);
jFrame.add(panelAddThread); }
}

I understand that you are asking for the code for the ActionListener for removeThread (JButton).
results is actually the last JPanel that you added, so that is the JPanel that you need to remove. However, once you remove it, you need to assign it to the new, last JPanel, i.e. the second last JPanel that was added.
Method getComponents returns all the components that were added, in the order that they were added. When you remove a component from a Container and subsequently call method getComponents, the array returned will not contain the component that you just removed. Hence the new, last JPanel is the last element in the array returned by method getComponents.
All that remains is to handle the "edge" cases.
Here is the code for the actionPerformed method:
removeThread.addActionListener(e -> {
if (results != null) {
jFrame.remove(results);
jFrame.repaint();
y -= 150;
Container contentPane = jFrame.getContentPane();
Component[] cmpts = contentPane.getComponents();
int count = cmpts.length;
if (count > 1) {
results = (JPanel) cmpts[count - 1];
}
else {
results = null;
}
}
});
If the user clicks removeThread before clicking addThread then results will be null.
If there is only one, added JPanel and we remove it, then we need to set results to null.
For completeness, here is the entire program, including the above changes.
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class lab3 {
static int y = 50;
static JButton addThread;
static JPanel results;
public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(550, 650);
jFrame.setTitle("Lab3");
jFrame.setVisible(true);
JPanel panelAddThread = new JPanel();
panelAddThread.setLayout(null);
panelAddThread.setBounds(0, 0, 550, 50);
panelAddThread.setBackground(Color.red);
JLabel threadLabel = new JLabel();
threadLabel.setText("Thread count: ");
addThread = new JButton();
addThread.setBounds(300, 0, 25, 25);
addThread.setText("+");
addThread.setBorder(null);
addThread.addActionListener(e -> {
results = new JPanel();
results.setBounds(0, y, 550, 150);
results.setBackground(Color.blue);
results.setLayout(null);
jFrame.add(results);
jFrame.repaint();
y = y + 150;
});
// Remove
JButton removeThread = new JButton();
removeThread.setBorder(null);
removeThread.setBounds(340, 0, 25, 25);
removeThread.setText("-");
removeThread.addActionListener(e -> {
if (results != null) {
jFrame.remove(results);
jFrame.repaint();
y -= 150;
Container contentPane = jFrame.getContentPane();
Component[] cmpts = contentPane.getComponents();
int count = cmpts.length;
if (count > 1) {
results = (JPanel) cmpts[count - 1];
}
else {
results = null;
}
}
});
panelAddThread.add(threadLabel);
panelAddThread.add(removeThread);
panelAddThread.add(addThread);
jFrame.add(panelAddThread);
}
}
However, I would write your program differently such that it uses Swing's layout managers. Consider the following:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class LabThree implements Runnable {
private JFrame frame;
private JPanel container;
private JPanel results;
public void run() {
buildAndDisplayGui();
}
private void buildAndDisplayGui() {
frame = new JFrame("Lab 3");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createButtonsPanel(), BorderLayout.PAGE_START);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createButtonsPanel() {
JPanel buttonsPanel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
buttonsPanel.setBackground(Color.red);
JButton addThreadButton = new JButton("\u2795");
addThreadButton.addActionListener(this::addThread);
buttonsPanel.add(addThreadButton);
JButton removeThreadButton = new JButton("\u2796");
removeThreadButton.addActionListener(this::removeThread);
buttonsPanel.add(removeThreadButton);
return buttonsPanel;
}
private JScrollPane createMainPanel() {
container = new JPanel();
container.setLayout(new BoxLayout(container, BoxLayout.PAGE_AXIS));
JScrollPane scrollPane = new JScrollPane(container);
scrollPane.setPreferredSize(new Dimension(570, 620));
return scrollPane;
}
private void addThread(ActionEvent event) {
results = new JPanel();
results.setBackground(Color.blue);
Dimension dim = new Dimension(550, 150);
results.setMaximumSize(dim);
results.setMinimumSize(dim);
results.setPreferredSize(dim);
container.add(results);
container.revalidate();
}
private void removeThread(ActionEvent event) {
if (results != null) {
container.remove(results);
Component[] cmpts = container.getComponents();
int count = cmpts.length;
if (count > 0) {
results = (JPanel) cmpts[count - 1];
}
else {
results = null;
}
container.revalidate();
container.repaint();
}
}
public static void main(String[] args) {
EventQueue.invokeLater(new LabThree());
}
}
All components added to a JFrame are actually added to its content pane which, by default, is a JPanel whose [default] layout manager is BorderLayout.
Usually you should call method setVisible (of class JFrame) only after you have added all the components.
After the GUI is displayed and you add or remove components from a container (such as JPanel), you need to call method revalidate. Sometimes you also need to call method repaint after you have called method revalidate.
If you click addThreadButton many times, not all the added JPanels will be visible, hence I use JScrollPane.
The text for addThreadButton is the Unicode heavy plus symbol and the text for removeThreadButton is the heavy minus symbol.
The ActionListeners are implemented using method references.
Although not required, it is recommended to explicitly launch the event dispatch thread (EDT), which is done in method main in the above code.

How can I draw multiple JLabels in different places? (icons don't show up)

I am trying to draw multiple icons in many different locations using for loop. For some reason they just don't show up. I don't know what I'm missing – only clue I found was about setting layout to null, but IntelliJ overwrites it.
Icons should show up in "mapa" panel. I tried adding them manually, but nothing changed.
My code:
package okna;
import logistyka.Walker;
import logistyka.errand.Errand;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
public class WalkerGUI extends JFrame{
private JPanel mainPanel;
private JLabel walkerName;
private JTextField walkerNameField;
private JLabel walkerAddress;
private JTextField walkerAddressField;
private JButton searchErrandsButton;
private JComboBox errandsComboBox;
private JLabel errandsList;
private JTextField walletValue;
private JLabel Wallet;
private JRadioButton archivalErrandsRadioButton;
private JRadioButton currentErrandsRadioButton;
private JButton payOutButton;
private JButton seeProfileButton;
private JPanel mapa;
ArrayList<Errand> masterErrandList = new ArrayList<>();
public WalkerGUI(Walker w, ArrayList<Errand> masterErrandList) {
setContentPane(mainPanel);
ArrayList<JLabel> errandsLabels = new ArrayList<>();
ImageIcon x = new ImageIcon(System.getProperty("user.dir") + "\\src\\x.png");
this.masterErrandList = masterErrandList;
for (Errand errand: masterErrandList) {
JLabel label = new JLabel("whtvr");
label.setIcon(x);
label.setLocation((int)errand.getAddress().getX(),(int)errand.getAddress().getY());
label.setMinimumSize(new Dimension(20,20));
label.setPreferredSize(new Dimension(20,20));
label.setVisible(true);
errandsLabels.add(label);
}
walkerNameField.setText(w.getDescription().getName());
walkerAddressField.setText(w.getDescription().getHomeRegion().getCurrentAddress().toString());
walletValue.setText(String.valueOf(w.getWalletSatus()));
seeProfileButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JFrame frame = new ProfileGUI(w);
frame.pack();
frame.setVisible(true);
}
});
payOutButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
w.setWalletSatus(0);
walletValue.setText(String.valueOf(w.getWalletSatus()));
}
});
}
}

You can use SpringLayout (rather than null layout). Method Errand.getAddress().getX() will return the distance of the left edge of the JLabel from the left edge of its container while Errand.getAddress().getY() will return the distance of the top edge of the JLabel from the top edge of its container.
The code in your question is not a minimal, reproducible example so the below code should be considered as a proof of concept.
import java.awt.EventQueue;
import java.awt.Point;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SpringLayout;
public class SprinGui {
private void createAndDisplayGui() {
JFrame frame = new JFrame("Spring");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel contentPane = (JPanel) frame.getContentPane();
SpringLayout layout = new SpringLayout();
contentPane.setLayout(layout);
Point[] points = new Point[]{new Point(5, 5),
new Point(5, 100),
new Point(225, 150),
new Point(250, 210)};
Class<?> meClass = getClass();
Icon[] icons = new Icon[4];
icons[0] = new ImageIcon(meClass.getResource("coffee.png"));
icons[1] = new ImageIcon(meClass.getResource("dollar.png"));
icons[2] = new ImageIcon(meClass.getResource("dynamite.png"));
icons[3] = new ImageIcon(meClass.getResource("soccer-player.png"));
for (int i = 0; i < 4; i++) {
JLabel label = new JLabel(icons[i]);
contentPane.add(label);
layout.putConstraint(SpringLayout.WEST,
label,
points[i].x,
SpringLayout.WEST,
contentPane);
layout.putConstraint(SpringLayout.NORTH,
label,
points[i].y,
SpringLayout.NORTH,
contentPane);
}
frame.setSize(450, 300);
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SprinGui instance = new SprinGui();
EventQueue.invokeLater(() -> instance.createAndDisplayGui());
}
}
This is how the GUI looks.
Note that How to Use Icons may also be helpful.

How to make my user-interface self adapt to the show and hide of JPanel?

Recently I'm writing a mail system client using Java (I chose swing to write the GUI and use IDEA to hardcode my GUI). In the Compose module, I want to show or hide the textfield for CC and Bcc when I click the corresponding buttons.
So I googled and browsed the following questions and doc on the web:
How to make JPanel scrollable in Java?
How to make JPanel scrollable?
Scrolling a JPanel
Doc: JScrollPane
Finally, I chose the JScrollPane to implement it.
My simplified sample code is as follows (the original code is tedious):
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Demo extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
private JLabel lbl1;
private JTextField txf1;
private JLabel lbl2;
private JTextField txf2;
// container for lbl2 and txf2, which should be able to be shown or hidden
private JPanel pnlContainer2;
private JLabel lbl3;
private JTextField txf3;
// container for lbl3 and txf3
private JPanel pnlContainer3;
private JButton btnShow;
// the container I want to move when I click btnShow
private JPanel pnlBody;
// the panel to hold my "cards"
// In this example, I include it just to show what controls are on my interface.
private JPanel pnlContent;
private JPanel pnlContainer;
// here, I want to use JScrollPane to make my pnlContainer scrollable
// to adapt to my interface
private JScrollPane scrollPane;
public Demo() {
init();
}
private void init() {
pnlContainer = new JPanel(new CardLayout(), true);
pnlContainer.setBounds(0, 0, 200, 180);
pnlContent = new JPanel(null, true);
pnlContent.setBounds(0, 0, 200, 180 + 50);
scrollPane = new JScrollPane(pnlContent, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
scrollPane.setBounds(0, 0, 200, 180);
pnlContainer.add(scrollPane);
pnlBody = new JPanel(null, true);
lbl1 = new JLabel("lbl1");
lbl1.setBounds(10, 20, 40, 30);
txf1 = new JTextField();
txf1.setBounds(60, 20, 120, 30);
pnlContent.add(lbl1);
pnlContent.add(txf1);
pnlContainer2 = new JPanel(null, true);
pnlContainer2.setBounds(0, 70, 180, 30);
lbl2 = new JLabel("lbl2");
lbl2.setBounds(10, 0, 40, 30);
txf2 = new JTextField();
txf2.setBounds(60, 0, 120, 30);
pnlContainer2.add(lbl2);
pnlContainer2.add(txf2);
pnlContainer2.setVisible(false);
pnlContent.add(pnlContainer2);
pnlBody = new JPanel(null, true);
pnlBody.setBounds(0, 70, 180, 90);
pnlContainer3 = new JPanel(null, true);
pnlContainer3.setBounds(0, 0, 180, 30);
pnlBody.add(pnlContainer3);
lbl3 = new JLabel("lbl3");
lbl3.setBounds(10, 0, 40, 30);
txf3 = new JTextField();
txf3.setBounds(60, 0, 120, 30);
pnlContainer3.add(lbl3);
pnlContainer3.add(txf3);
btnShow = new JButton("show");
btnShow.setBounds(60, 50, 80, 30);
btnShow.addActionListener(this);
pnlBody.add(btnShow);
pnlContent.add(pnlBody);
this.add(pnlContainer);
this.setLayout(null);
this.setTitle("Demo");
this.setSize(200, 200);
this.setLocationRelativeTo(null);
this.setVisible(true);
this.setResizable(false);
// ImageIcon icon = new ImageIcon("E:\\Javarepo\\Hmail\\src\\main\\resources\\assets\\hmail.png");
// this.setIconImage(icon.getImage());
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
Object src = e.getSource();
if (src instanceof JButton) {
JButton btn = (JButton) src;
boolean showSelected = false;
String altText;
if (btn == btnShow) {
showSelected = btnShow.getText() == "show";
altText = showSelected ? "hide" : "show";
btnShow.setText(altText);
}
relayout(showSelected);
}
}
private void relayout(boolean showSelected) {
int x = pnlBody.getX();
int y = pnlBody.getY();
if (showSelected) {
pnlContainer2.setVisible(true);
pnlBody.setBounds(x, y + 50, 180, 90);
} else {
pnlContainer2.setVisible(false);
pnlBody.setBounds(x, y - 50, 180, 90);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new Demo());
}
}
However, no matter which JPanel I apply JScrollPane to, I cannot make my interface adaptive to the hide and show of my JContainer2.
How can I modify it, or what control to use to replace JScrollPane? Any suggestions will be welcome.
And here is my platform information:
java -version
java version "1.8.0_212"
Java(TM) SE Runtime Environment (build 1.8.0_212-b10)
Java HotSpot(TM) 64-Bit Server VM (build 25.212-b10, mixed mode)
OS: win10 1909
arch: amd64

I rewrote your code. Explanations appear after it.
import java.awt.BorderLayout;
import java.awt.EventQueue;
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.JScrollPane;
import javax.swing.JTextField;
import javax.swing.ScrollPaneConstants;
import javax.swing.WindowConstants;
public class Demo2 implements ActionListener, Runnable {
private static final String HIDE = "HIDE";
private static final String SHOW = "SHOW";
private JButton button;
private JLabel lbl2;
private JFrame frame;
private JTextField txf2;
#Override
public void run() {
showGui();
}
#Override
public void actionPerformed(ActionEvent event) {
boolean visible;
String text;
String actionCommand = event.getActionCommand();
switch (actionCommand) {
case HIDE:
text = SHOW;
visible = false;
break;
case SHOW:
text = HIDE;
visible = true;
break;
default:
text = "???";
visible = false;
}
button.setText(text);
lbl2.setVisible(visible);
txf2.setVisible(visible);
}
private JPanel createButtonsPanel() {
JPanel buttonsPanel = new JPanel();
button = new JButton(SHOW);
button.addActionListener(this);
buttonsPanel.add(button);
return buttonsPanel;
}
private JScrollPane createForm() {
JPanel form = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
JLabel lbl1 = new JLabel("lbl1");
form.add(lbl1, gbc);
gbc.gridx = 1;
JTextField txf1 = new JTextField(6);
form.add(txf1, gbc);
gbc.gridx = 0;
gbc.gridy = 1;
lbl2 = new JLabel("lbl2");
lbl2.setVisible(false);
form.add(lbl2, gbc);
gbc.gridx = 1;
txf2 = new JTextField(6);
txf2.setVisible(false);
form.add(txf2, gbc);
gbc.gridx = 0;
gbc.gridy = 2;
JLabel lbl3 = new JLabel("lbl3");
form.add(lbl3, gbc);
gbc.gridx = 1;
JTextField txf3 = new JTextField(6);
form.add(txf3, gbc);
return new JScrollPane(form,
ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
}
private void showGui() {
frame = new JFrame("Demo");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.add(createForm(), BorderLayout.CENTER);
frame.add(createButtonsPanel(), BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
/**
* Start here.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Demo2());
}
}
You should always try to use a layout manager. The code above uses GridBagLayout but there are several other layout managers that are good at handling forms, including GroupLayout and SpringLayout as well as third party layout managers like MiG Layout and FormLayout.
In order to "show" and "hide" the middle row in your form, simply set the visible property to true or false. If the text of the button is SHOW, then when the user clicks on it, I change the button text to HIDE and make lbl2 and txf2 both visible. If the button text is HIDE, then when the user clicks the button I change the text to SHOW and make lbl2 and txf2 not visible.
Because I use a layout manager, it handles resizing the JPanel whenever the contents of the JPanel are changed. When you don't use a layout manager, then you have to write code that handles the resizing and of-course your code does not, hence your problem.

add multiple JPanels in the middle of the window

I want to create an input JFrame where the program reads three fields (model, week and plan), and after inserting one line the user can choose to input new values on a different row, this is done pressing a JLabel with a image add icon.
My expectation is to be able to add a new JPanel (called body in the subclass) right under the last one (JPanel lastContent global variable), and to be able to remove or add new ones as the user needs.
Below is my code so far:
package marquesina;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Toolkit;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import org.jdesktop.swingx.HorizontalLayout;
import org.jdesktop.swingx.VerticalLayout;
public class JModificaciones extends Container {
private JPanel lastContent;
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame("DEMO");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up the content pane.
JModificaciones mods = new JModificaciones();
frame.setContentPane(mods);
//Display the window.
frame.pack();
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
frame.setLocation(
dim.width / 2 - frame.getSize().width / 2,
dim.height / 2 - frame.getSize().height / 2);
frame.setVisible(true);
});
}
public JModificaciones() {
initComponents();
System.out.println("New Panel Created");
}
private void initComponents() {
JPanel jHeader = new JPanel();
JLabel jLMod = new JLabel();
JLabel jLSem = new JLabel();
JLabel jLPlan = new JLabel();
JPanel jFooter = new JPanel();
JButton jGuardar = new JButton();
JButton jCancelar = new JButton();
setLayout(new VerticalLayout(10));
//HEADER
jHeader.setLayout(new HorizontalLayout());
jLMod.setText("Model");
jHeader.add(jLMod);
jLWeek.setText("Week");
jHeader.add(jLWeek);
jLPlan.setText("Plan");
jHeader.add(jLPlan);
add(jHeader);
//CONTENT
add(new jContent());
//FOOTER
jGuardar.setText("Save");
jFooter.add(jGuardar);
jCancelar.setText("Cancel");
jFooter.add(jCancel);
add(jFooter);
}
public class jContent extends JPanel {
JLabel jAdd = new javax.swing.JLabel();
JLabel jDelete = new javax.swing.JLabel();
public jContent() {
JPanel body = new JPanel(new HorizontalLayout());
JTextField jModel = new JTextField();
JTextField jWeek = new JTextField();
JTextField jPlan = new JTextField();
body.setLayout(new org.jdesktop.swingx.HorizontalLayout());
jModel.setPreferredSize(new java.awt.Dimension(100, 28));
body.add(jModel);
jWeek.setPreferredSize(new java.awt.Dimension(100, 28));
body.add(jWeek);
jPlan.setPreferredSize(new java.awt.Dimension(100, 28));
body.add(jPlan);
jAdd.setIcon(
new javax.swing.ImageIcon(
getClass().getResource("add.png")));
jAdd.addMouseListener(new java.awt.event.MouseAdapter() {
#Override
public void mouseClicked(java.awt.event.MouseEvent evt) {
}
});
body.add(jAdd);
jDelete.setIcon(
new javax.swing.ImageIcon(
getClass().getResource("delete.png")));
jDelete.addMouseListener(new java.awt.event.MouseAdapter() {
#Override
public void mouseClicked(java.awt.event.MouseEvent evt) {
remove(lastContent);
}
});
body.add(jDelete);
add(body);
}
}
}
However I'm not able to add a new JPanel (which I want to create when the user clicks on the jAdd JLabel), I can't come up with a way to reference the JPanel where I want to put my new Components and using just add() or remove() as I do in the above code just reference the MouseListener, not the JPanel created in the sublcass...

about layouts in simple calculator

hi there i am trying to make a calculator with coding sizes,layouts etc. by myself (trying to not use NetBeans and it is not a homework). but i am facing with a problem about empty spaces. i have a TextArea and Buttons but as you can see below i cant handle this space problem. here is my code,
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.JTextArea;
public class calculator extends JFrame {
public calculator(){
initComponents();
}
private void initComponents(){
JPanel panelScreen = new JPanel(new GridLayout(0,1));
JTextArea screen = new JTextArea();
panelScreen.add(screen);
JFrame frame = new JFrame("CALCULATOR");
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
JPanel panelButtons = new JPanel(new GridLayout(3,3));
JButton oneButton = new JButton("1");
panelButtons.add(oneButton);
JButton twoButton = new JButton("2");
panelButtons.add(twoButton);
JButton threeButton = new JButton("3");
panelButtons.add(threeButton);
JButton fourButton = new JButton("4");
panelButtons.add(fourButton);
JButton fiveButton = new JButton("5");
panelButtons.add(fiveButton);
JButton sixButton = new JButton("6");
panelButtons.add(sixButton);
JButton sevenButton = new JButton("7");
panelButtons.add(sevenButton);
JButton eightButton = new JButton("8");
panelButtons.add(eightButton);
JButton nineButton = new JButton("9");
panelButtons.add(nineButton);
frame.getContentPane().add(panelScreen, BorderLayout.NORTH);
//frame.getContentPane().add(new JSeparator(), BorderLayout.CENTER);
frame.getContentPane().add(panelButtons, BorderLayout.SOUTH);
frame.setBounds(50, 50, 500, 500);
frame.setResizable(false);
//frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
new calculator();
}
}
and this the picture of programme;
i appreciate if you can help me. anyway thanks :)

A few suggestions:
Don't set the JFrame's size, and in fact don't set any sizes.
Call pack to all the components to set their own sizes.
If you want the buttons bigger, consider changing the size of their fonts.
e.g.,
import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import javax.swing.*;
public class Calc2 {
public static final String[][] BUTTON_TEXTS = {
{"7", "8", "9", "+"},
{"4", "5", "6", "-"},
{"1", "2", "3", "*"},
{"0", ".", "/", "="}
};
public static final Font BTN_FONT = new Font(Font.SANS_SERIF, Font.BOLD, 24);
private static void createAndShowGui() {
JTextField field = new JTextField(10);
field.setFont(BTN_FONT.deriveFont(Font.PLAIN));
JPanel btnPanel = new JPanel(new GridLayout(BUTTON_TEXTS.length,
BUTTON_TEXTS[0].length));
for (int i = 0; i < BUTTON_TEXTS.length; i++) {
for (int j = 0; j < BUTTON_TEXTS[i].length; j++) {
JButton btn = new JButton(BUTTON_TEXTS[i][j]);
btn.setFont(BTN_FONT);
btnPanel.add(btn);
}
}
JPanel mainPanel = new JPanel(new BorderLayout());
mainPanel.add(field, BorderLayout.PAGE_START);
mainPanel.add(btnPanel, BorderLayout.CENTER);
JFrame frame = new JFrame("Calc2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
// no need to extend frame!
//public class Calculator extends JFrame {
public class Calculator {
public Calculator(){
initComponents();
}
private void initComponents(){
// I find it easier to create a panel and SET it as the content pane
JPanel gui = new JPanel(new BorderLayout(5,5));
// add some padding to the main GUI
gui.setBorder(new EmptyBorder(4,4,4,4));
// not needed if only a single compoinent is to be added!
//JPanel panelScreen = new JPanel(new GridLayout(0,1));
// add some constraints to make the output field bigger.
// if it is intended to be single line, a JTextField should be used.
JTextArea screen = new JTextArea(2,25);
gui.add(screen, BorderLayout.NORTH);
//panelScreen.add(screen);
JFrame frame = new JFrame("CALCULATOR");
frame.setContentPane(gui);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// add padding around the buttons
JPanel panelButtons = new JPanel(new GridLayout(3,3,4,4));
JButton oneButton = new JButton("1");
panelButtons.add(oneButton);
JButton twoButton = new JButton("2");
panelButtons.add(twoButton);
JButton threeButton = new JButton("3");
panelButtons.add(threeButton);
JButton fourButton = new JButton("4");
panelButtons.add(fourButton);
JButton fiveButton = new JButton("5");
panelButtons.add(fiveButton);
JButton sixButton = new JButton("6");
panelButtons.add(sixButton);
JButton sevenButton = new JButton("7");
panelButtons.add(sevenButton);
JButton eightButton = new JButton("8");
panelButtons.add(eightButton);
JButton nineButton = new JButton("9");
panelButtons.add(nineButton);
//frame.getContentPane().add(new JSeparator(), BorderLayout.CENTER);
// Add the buttons to the CENTER and they will
// fill whatever space they are provided.
gui.add(panelButtons, BorderLayout.CENTER);
//frame.setBounds(50, 50, 500, 500);
//frame.setResizable(false);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Calculator();
}
});
}
}

You might like to study this example that follows the suggestions of #HFOE and #mre. Note that "size" appears nowhere in the code.

Read Laying Out Components Within a Container
Implement appropriate layout(s)
EDIT -
Quick solution - replace the JFrame layout manager with BoxLayout (i.e. setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS))).