Java GUI How to make an event when I press a JButton? - java

I want to make a keyboard. If I press the button it has to come up at 2.(pic). I think it's a similar way to make a calculator. Can I have some advice?
Actually I don't even know if this right. Am I OK making a JButton like that?
This is my code.
package assignment;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.LayoutManager;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Random extends JFrame {
Random() {
setTitle("보안 키보드");
setLayout(new BorderLayout(10, 10));
showNorth();
showCenter();
showSouth();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(450,500);// 창크기를 정한다
setVisible(true);}
void showNorth() {
JTextField area1 = new JTextField();
JTextField area2 = new JTextField();
JPanel panel = new JPanel(new GridLayout(2, 0));
}
area2.setText("보안문자를 입력하세요.");
area1.setHorizontalAlignment(JTextField.CENTER);
area2.setHorizontalAlignment(JTextField.CENTER);
area1.setEditable(false);
area2.setEditable(false);
panel.add(area1);
panel.add(area2);
add(panel, BorderLayout.NORTH);
}
void showCenter() {
JPanel p3 = new JPanel(new GridLayout(4, 4));
p3.setLayout(new GridLayout(5, 5, 5, 5));
// 버튼 생성하기
JButton ba = new JButton("");
JButton bb = new JButton("");
JButton bc = new JButton("");
JButton bd = new JButton("");
JButton b0 = new JButton("0");
JButton b1 = new JButton("1");
JButton b2 = new JButton("2");
JButton b3 = new JButton("3");
JButton b4 = new JButton("4");
JButton b5 = new JButton("5");
JButton b6 = new JButton("6");
JButton b7 = new JButton("7");
JButton b8 = new JButton("8");
JButton b9 = new JButton("9");
JButton er1 = new JButton("하나\n지움");
JButton erall = new JButton("전체\n지움");
p3.add(ba);// 버튼을 패널에 부착시킨다
p3.add(bb);
p3.add(bc);
p3.add(bd);
p3.add(b0);
p3.add(b1);
p3.add(b2);
p3.add(b3);
p3.add(b4);
p3.add(b5);
p3.add(b6);
p3.add(b7);
p3.add(b8);
p3.add(b9);
p3.add(er1);
p3.add(erall);
add(p3, BorderLayout.CENTER); // 패널을 프레임의 중앙에 추가한다.
}
void showSouth() {
JPanel p4 = new JPanel();
JButton complete = new JButton("입력완료"); // 입력완료 버튼 생성
p4.add(complete);
p4.setLayout((LayoutManager) new FlowLayout(FlowLayout.TRAILING));
add(p4, BorderLayout.SOUTH);
}
public static void main(String[] args) {
new Random();
}
}

First of all, the code needs extreme refactor. But as you the OOP beginner, lets dive into your problem. Your class called Random needs to implement ActionListener interface and override actionPerformed method:
#Override
public void actionPerformed(ActionEvent e) {
}
Then, what you want to do is to add action listeners and set action commands for the buttons, for instance:
button.addActionListener(this);
button.addActionCommand("button")
Now you can know which button was clicked and represent something on your JTextField:
#Override
public void actionPerformed(ActionEvent e) {
if(e.getActionCommand().equals("button")){
textField.setText("button was clicked");
}
}

Related

Can I use a for loop to create objects in java?

Can I initialize multiple objects in a single loop?
Here's what a snippet of my code looks like. As you can see, it becomes hard to look at from a glance and takes up too much space.
I'd like to be able to create the buttons in one for loop and then modify in another for loop.
public class MyFrame extends JFrame {
MyFrame() {
JButton button1 = new JButton();
JButton button2 = new JButton();
JButton button3 = new JButton();
JButton button4 = new JButton();
JButton button5 = new JButton();
JButton button6 = new JButton();
JButton button7 = new JButton();
JButton button8 = new JButton();
JButton button9 = new JButton();
JButton button0 = new JButton();
button1.setBounds(60, 60, 50, 50);
button2.setBounds(120,60,50,50);
button3.setBounds(180,60,50,50);
button4.setBounds(60,120,50,50);
button5.setBounds(120,120,50,50);
button6.setBounds(180,120,50,50);
button7.setBounds(60,180,50,50);
button8.setBounds(120,180,50,50);
button9.setBounds(180,180,50,50);
button0.setBounds(120,240,50,50);
}
}
Yes, you can use a for loop to create the buttons.
Here's a GUI I created.
It's not a good idea to use absolute positioning (setBounds) when creating a GUI. You should use the Swing layout managers.
I used a GridLayout to position the buttons.
Here's the complete runnable code.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
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 TenButtonGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new TenButtonGUI());
}
#Override
public void run() {
JFrame frame = new JFrame("Ten Button GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createMainPanel() {
JPanel panel = new JPanel(new GridLayout(0, 3, 5, 5));
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
for (int i = 0; i < 11; i++) {
if (i == 9) {
JLabel label = new JLabel(" ");
panel.add(label);
} else {
JButton button = new JButton();
button.setPreferredSize(new Dimension(50, 50));
panel.add(button);
}
}
return panel;
}
}
You could do something like this:
List<JButton> buttons = new ArrayList<>();
int[][] bounds = {{60, 60, 50, 50}, {120,60,50,50}}; //add more bound quadruplets
// iterating over the values in the bounds array
Arrays.asList(bounds).forEach(v -> {
JButton button = new JButton();
button.setBounds(v[0], v[1], v[2], v[3]);
buttons.add(button);
});
In the end you will find your buttons in the buttons List.

How to separate a JTextField from the rest of the GridLayout

I'm trying to make a calculator as a fun project. But as I try to make it look like a... calculator, it just turns out like one big grid, as follows:
I've tried to follow along with whatever I found on the Internet, but that was a big bust.
Can anyone help me out trying to separate the JTextField so it doesn't do this, and it can be in it's own row?
Here's the code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Main extends JFrame {
public Main() {
// Row = ->
// Column = ^
Container cp = getContentPane();
cp.setLayout(new GridLayout(3, 0));
JTextField txtCalc = new JTextField("0");
txtCalc.setHorizontalAlignment(SwingConstants.RIGHT);
JButton btn0 = new JButton("0");
JButton btn1 = new JButton("1");
JButton btn2 = new JButton("2");
JButton btn3 = new JButton("3");
JButton btn4 = new JButton("4");
JButton btn5 = new JButton("5");
JButton btn6 = new JButton("6");
JButton btn7 = new JButton("7");
JButton btn8 = new JButton("8");
JButton btn9 = new JButton("9");
JButton btn10 = new JButton("10");
cp.add(txtCalc);
cp.add(btn0);
cp.add(btn1);
cp.add(btn2);
cp.add(btn3);
cp.add(btn4);
cp.add(btn5);
cp.add(btn6);
cp.add(btn7);
cp.add(btn8);
cp.add(btn9);
cp.add(btn10);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Calculator");
setSize(600, 600);
setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(Main::new);
}
}
Edit:
Now I have the answer! This is my fixed code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Main extends JFrame {
public Main() {
Container cp = getContentPane();
cp.setLayout(new GridLayout(3, 0));
JPanel mainPanel = new JPanel(new BorderLayout());
JPanel buttonPanel = new JPanel(new GridLayout(3, 0));
setContentPane(border);
JTextField txtCalc = new JTextField("0");
txtCalc.setHorizontalAlignment(SwingConstants.RIGHT);
txtCalc.setEditable(true);
JButton btn1 = new JButton("1");
JButton btn2 = new JButton("2");
JButton btn3 = new JButton("3");
JButton btn4 = new JButton("4");
JButton btn5 = new JButton("5");
JButton btn6 = new JButton("6");
JButton btn7 = new JButton("7");
JButton btn8 = new JButton("8");
JButton btn9 = new JButton("9");
JButton btn0 = new JButton("0");
mainPanel.add(buttonPanel, BorderLayout.CENTER);
mainPanel.add(txtCalc, BorderLayout.NORTH);
buttonPanel.add(btn1);
buttonPanel.add(btn2);
buttonPanel.add(btn3);
buttonPanel.add(btn4);
buttonPanel.add(btn5);
buttonPanel.add(btn6);
buttonPanel.add(btn7);
buttonPanel.add(btn8);
buttonPanel.add(btn9);
buttonPanel.add(btn0);
public static void main(String[] args) {
SwingUtilities.invokeLater(Main::new);
}
}
Have your main panel use a BorderLayout. Put the JTextField in the North position. Put your buttons in a panel that uses GridLayout, then add that panel to your main panel in the Center position.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Main extends JFrame {
public Main() {
JPanel mainPanel = new JPanel(new BorderLayout());
setContentPane(mainPanel);
JTextField txtCalc = new JTextField("0");
txtCalc.setHorizontalAlignment(SwingConstants.RIGHT);
JPanel buttonPanel = new JPanel(new GridLayout(3, 0));
JButton btn0 = new JButton("0");
JButton btn1 = new JButton("1");
JButton btn2 = new JButton("2");
JButton btn3 = new JButton("3");
JButton btn4 = new JButton("4");
JButton btn5 = new JButton("5");
JButton btn6 = new JButton("6");
JButton btn7 = new JButton("7");
JButton btn8 = new JButton("8");
JButton btn9 = new JButton("9");
buttonPanel.add(txtCalc);
buttonPanel.add(btn0);
buttonPanel.add(btn1);
buttonPanel.add(btn2);
buttonPanel.add(btn3);
buttonPanel.add(btn4);
buttonPanel.add(btn5);
buttonPanel.add(btn6);
buttonPanel.add(btn7);
buttonPanel.add(btn8);
buttonPanel.add(btn9);
mainPanel.add(txtCalc, BorderLayout.NORTH);
mainPanel.add(buttonPanel, BorderLayout.CENTER);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Calculator");
setSize(600, 600);
setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(Main::new);
}
}

ActionListener not working on JButton

I have written a code to display three buttons in three panels on a
frame with grid layout.
The objective is to
- change color of button when the button is clicked
- initially all 3 of them are black
The code runs perfectly except for the color of button doesn't change on
click.
Can anyone please point out the problem or debug it.
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class gui extends JFrame implements ActionListener {
JPanel p1, p2, p3;
JButton b1, b2, b3;
public gui() {
setLayout(new GridLayout(3, 1));
JPanel p1 = new JPanel(new GridLayout(1, 1));
JPanel p2 = new JPanel(new GridLayout(1, 1));
JPanel p3 = new JPanel(new GridLayout(1, 1));
JButton b1 = new JButton();
JButton b2 = new JButton();
JButton b3 = new JButton();
b1.setBackground(Color.BLACK);
b2.setBackground(Color.BLACK);
b3.setBackground(Color.BLACK);
b1.addActionListener(this);
p1.add(b1);
b2.addActionListener(this);
p2.add(b2);
b3.addActionListener(this);
p3.add(b3);
add(p1);
add(p2);
add(p3);
}
public void actionPerformed(ActionEvent e) //function to handle click
{
if (e.getSource() == b1) {
b1.setBackground(Color.RED);
} else if (e.getSource() == b2) {
b1.setBackground(Color.YELLOW);
} else if (e.getSource() == b3) {
b3.setBackground(Color.BLUE);
}
}
public static void main(String[] args) {
gui ob1 = new gui();
ob1.setSize(1000, 500);
ob1.setLocation(100, 100);
ob1.setVisible(true);
ob1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
You have to initialize the buttons using[Same applied to panels as well]
b1 = new JButton();
b2 = new JButton();
b3 = new JButton();
because you are creating local variables which hides the global variables
JButton b1 = new JButton();//local variables
JButton b2 = new JButton();
JButton b3 = new JButton();
In the second if condition you have to change the color of b2 not b1
else if(e.getSource()==b2){
//b1.setBackground(Color.YELLOW);
b2.setBackground(Color.YELLOW);
}
Always use .equals() instead of == to compare objects
e.getSource().equals(b1)

Adding a JPanel to an ActionListener

I have created a JPanel that has all the JRadioButtons on it that I need (it is called PortSettings). I also have a button, called port settings, when the user clicks the button, I need the JPanel to come up and display the radio buttons. I have tried to add the JPanel to the actionlistener but it doesn't work. My code is below. I have deleted all other ActionListener's from the other buttons except for the portsettings buttons. If this question is confusing I'm sorry. It's really hard to explain what I need to do. I have uploaded a drawing of what the panel will look like as well as a screenshot of my program.
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JRadioButton;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
public class TestApplication implements ActionListener {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(1000, 1000);
frame.setTitle("RBA Test Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
JTextArea text = new JTextArea();
JLabel logLabel = new JLabel("Input/Output Log");
JRadioButton apprve = new JRadioButton("Approve");
JRadioButton decline = new JRadioButton("Decline");
JRadioButton ethernet = new JRadioButton("Ethernet");
JRadioButton rs = new JRadioButton("RS232");
JRadioButton usbcdc = new JRadioButton("USB_CDC");
JRadioButton usbhid = new JRadioButton("USB_HID");
JButton next = new JButton("Next");
JButton ok = new JButton("OK");
JButton cancel = new JButton("Cancel");
JPanel PortSettings = new JPanel();
PortSettings.add(ethernet);
PortSettings.add(rs);
PortSettings.add(usbcdc);
PortSettings.add(usbhid);
PortSettings.add(next);
PortSettings.add(cancel);
JButton initialize = new JButton("Initialize");
JButton connect = new JButton("Connect");
JButton disconnect = new JButton("Disconnect");
JButton shutdown = new JButton("Shut Down");
JButton portsettings = new JButton("Port Settings");
portsettings.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
JButton online = new JButton("Go Online");
JButton offline = new JButton("Go Offline");
JButton status = new JButton("Status");
JButton reboot = new JButton("Reboot");
JButton account = new JButton("Account");
JButton amount = new JButton("Amount");
JButton reset = new JButton("Reset");
JButton approvordecl = new JButton("Approve / Decline");
JButton test = new JButton("Test Button #1");
JButton testing = new JButton("Test Button #2");
JRadioButton button = new JRadioButton("Radio Button");
JRadioButton button2 = new JRadioButton("Radio Button");
JCheckBox checkbox = new JCheckBox("Check Box");
JCheckBox checkbox2 = new JCheckBox("Check Box");
JPanel testPanel = new JPanel();
testPanel.add(button);
testPanel.add(button2);
testPanel.add(checkbox2);
JPanel posPanel = new JPanel();
posPanel.add(test);
posPanel.add(testing);
posPanel.add(checkbox);
JPanel llpPanel = new JPanel();
llpPanel.add(online);
llpPanel.add(offline);
llpPanel.add(status);
llpPanel.add(reboot);
llpPanel.add(account);
llpPanel.add(amount);
llpPanel.add(reset);
llpPanel.add(approvordecl);
JPanel textPanel = new JPanel(new BorderLayout());
textPanel.add(logLabel);
frame.add(logLabel);
JPanel buttonPanel = new JPanel();
buttonPanel.add(initialize);
buttonPanel.add(connect);
buttonPanel.add(disconnect);
buttonPanel.add(shutdown);
buttonPanel.add(portsettings);
frame.add(buttonPanel);
frame.add(buttonPanel, BorderLayout.NORTH);
JTabbedPane tabbedPane = new JTabbedPane();
tabbedPane.addTab("LLP", null, llpPanel, "Low Level Protocol");
tabbedPane.addTab("POS",null, posPanel, "Point Of Sale");
tabbedPane.addTab("Test", null, testPanel, "Test");
JPanel tabsPanel = new JPanel(new BorderLayout());
tabsPanel.add(tabbedPane);
frame.add(tabsPanel, BorderLayout.CENTER);
frame.pack();
}
#Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
}
}
I have tried to add a JFrame to the ActionListener then add the JPanel to the JFrame but nothing happens when I click the Port Settings button. Also, when I tried to add the JPanel to the JFrame it told me to put final in front of JPanel PortSettings = new JPanel();. Here is the code.
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JRadioButton;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
public class TestApplication implements ActionListener {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(1000, 1000);
frame.setTitle("RBA Test Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
JTextArea text = new JTextArea();
JLabel logLabel = new JLabel("Input/Output Log");
JRadioButton apprve = new JRadioButton("Approve");
JRadioButton decline = new JRadioButton("Decline");
JRadioButton ethernet = new JRadioButton("Ethernet");
JRadioButton rs = new JRadioButton("RS232");
JRadioButton usbcdc = new JRadioButton("USB_CDC");
JRadioButton usbhid = new JRadioButton("USB_HID");
JButton next = new JButton("Next");
JButton ok = new JButton("OK");
JButton cancel = new JButton("Cancel");
final JPanel PortSettings = new JPanel();
PortSettings.add(ethernet);
PortSettings.add(rs);
PortSettings.add(usbcdc);
PortSettings.add(usbhid);
PortSettings.add(next);
PortSettings.add(cancel);
JPanel accountButton = new JPanel();
accountButton.add(ok);
accountButton.add(cancel);
JPanel apprvordecl = new JPanel();
apprvordecl.add(apprve);
apprvordecl.add(decline);
JPanel amountButton = new JPanel();
amountButton.add(ok);
amountButton.add(cancel);
JButton initialize = new JButton("Initialize");
JButton connect = new JButton("Connect");
JButton disconnect = new JButton("Disconnect");
JButton shutdown = new JButton("Shut Down");
JButton portsettings = new JButton("Port Settings");
portsettings.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JFrame port = new JFrame("Port Settings");
port.add(PortSettings);
frame.setVisible(true);
}
});
JButton online = new JButton("Go Online");
JButton offline = new JButton("Go Offline");
JButton status = new JButton("Status");
JButton reboot = new JButton("Reboot");
JButton account = new JButton("Account");
JButton amount = new JButton("Amount");
JButton reset = new JButton("Reset");
JButton approvordecl = new JButton("Approve / Decline");
JButton test = new JButton("Test Button #1");
JButton testing = new JButton("Test Button #2");
JRadioButton button = new JRadioButton("Radio Button");
JRadioButton button2 = new JRadioButton("Radio Button");
JCheckBox checkbox = new JCheckBox("Check Box");
JCheckBox checkbox2 = new JCheckBox("Check Box");
JPanel testPanel = new JPanel();
testPanel.add(button);
testPanel.add(button2);
testPanel.add(checkbox2);
JPanel posPanel = new JPanel();
posPanel.add(test);
posPanel.add(testing);
posPanel.add(checkbox);
JPanel llpPanel = new JPanel();
llpPanel.add(online);
llpPanel.add(offline);
llpPanel.add(status);
llpPanel.add(reboot);
llpPanel.add(account);
llpPanel.add(amount);
llpPanel.add(reset);
llpPanel.add(approvordecl);
JPanel textPanel = new JPanel(new BorderLayout());
textPanel.add(logLabel);
frame.add(logLabel);
JPanel buttonPanel = new JPanel();
buttonPanel.add(initialize);
buttonPanel.add(connect);
buttonPanel.add(disconnect);
buttonPanel.add(shutdown);
buttonPanel.add(portsettings);
frame.add(buttonPanel);
frame.add(buttonPanel, BorderLayout.NORTH);
JTabbedPane tabbedPane = new JTabbedPane();
tabbedPane.addTab("LLP", null, llpPanel, "Low Level Protocol");
tabbedPane.addTab("POS",null, posPanel, "Point Of Sale");
tabbedPane.addTab("Test", null, testPanel, "Test");
JPanel tabsPanel = new JPanel(new BorderLayout());
tabsPanel.add(tabbedPane);
frame.add(tabsPanel, BorderLayout.CENTER);
frame.pack();
}
#Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
}
}
You´re on the right track, but you do not want to add your PortSettings panel to a new JFrame but somewhere on your previously built one, assigned to the local variable frame. So your action listener should rather be
portsettings.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frame.add(PortSettings, BorderLayout.SOUTH);
frame.pack();
}
});
(This is assuming that you actually want to add it to the frame at that instant and not add it invisibly right from the start and turn it visible, like #Aleksei suggested.)
The error message about final is because you use PortSettings in an (anonymous) inner class - viz., the ActionListener. In my proposed modification the same goes for frame, so you need to adapt its declaration as well:
final JFrame frame = new JFrame();
The reason why is quite technical and beside the point right now: just do it.
If instead you want the panel to appear in a separate window, you need a JDialog for that, not a second JFrame:
portsettings.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JDialog dialog = new JDialog(frame);
dialog.add(PortSettings);
dialog.pack();
dialog.setVisible(true);
}
});
Take a look at the JOptionPane class for a rich choice of ways to get more functionality out of dialogs.
Just add the action listener to all your buttons.
like this:
yourButton.addActionListener(this);
Do that for all the buttons.
Then take your TestPalication class's actionPreformed method and do whatever:
#Override
public void actionPerformed(ActionEvent arg0) {
((JRadioButton) arg0.getSource()).setTitle("Clicked!");
}
Your question was a little bit confusing but I hope this clarifies a little bit.

how to print multiple numbers to a label with keypad buttons

Hello this is really long I'm sorry My code works but how do I print multiple numbers to my label with just pressing buttons. My code isn't complete but I just want a push in the right direction. Thank you for any help you can give.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.event.*;
public class NumericKeyPadPanel extends JPanel {
private JButton b1, b2, b3, b4, b5, b6, b7, b8, b9, b10, b11, b12, clear;
private JLabel label1;
private JPanel primary, panel2, panel3, panel4;
public NumericKeyPadPanel() {
label1 = new JLabel();
primary = new JPanel();
panel2 = new JPanel();
panel3 = new JPanel();
panel4 = new JPanel();
//Set up for the center grid
panel2.setLayout(new GridLayout(4, 3));
panel2.setBackground(Color.gray);
panel2.setBorder(BorderFactory.createLineBorder(Color.black, 4));
//set up for the top box
panel3.setBackground(Color.white);
panel3.setBorder(BorderFactory.createEtchedBorder());
panel3.add(label1);
//set up for the bottom
panel4.setBackground(Color.gray);
//set up for the buttons for center and bottom
ButtonListener listener1 = new ButtonListener();
ButtonListener listener2 = new ButtonListener();
ButtonListener listener3 = new ButtonListener();
ButtonListener listener4 = new ButtonListener();
ButtonListener listener5 = new ButtonListener();
ButtonListener listener6 = new ButtonListener();
ButtonListener listener7 = new ButtonListener();
ButtonListener listener8 = new ButtonListener();
ButtonListener listener9 = new ButtonListener();
ButtonListener listener10 = new ButtonListener();
ButtonListener listener11 = new ButtonListener();
ButtonListener listener12 = new ButtonListener();
ButtonListener listener13 = new ButtonListener();
b1 = new JButton("1");
b1.addActionListener(listener1);
b2 = new JButton("2");
b2.addActionListener(listener2);
b3 = new JButton("3");
b3.addActionListener(listener3);
b4 = new JButton("4");
b4.addActionListener(listener4);
b5 = new JButton("5");
b5.addActionListener(listener5);
b6 = new JButton("6");
b6.addActionListener(listener6);
b7 = new JButton("7");
b7.addActionListener(listener7);
b8 = new JButton("8");
b8.addActionListener(listener8);
b9 = new JButton("9");
b9.addActionListener(listener9);
b10 = new JButton("*");
b10.addActionListener(listener10);
b11 = new JButton("0");
b11.addActionListener(listener11);
b12 = new JButton("#");
b12.addActionListener(listener12);
clear = new JButton("Clear");
clear.addActionListener(listener13);
panel2.add(b1);
panel2.add(b2);
panel2.add(b3);
panel2.add(b4);
panel2.add(b5);
panel2.add(b6);
panel2.add(b7);
panel2.add(b8);
panel2.add(b9);
panel2.add(b10);
panel2.add(b11);
panel2.add(b12);
panel4.add(clear);
//set up for main panel
primary.setLayout(new BorderLayout());
primary.setBackground(Color.gray);
primary.add(panel2, BorderLayout.CENTER);
primary.add(panel3, BorderLayout.NORTH);
primary.add(panel4, BorderLayout.SOUTH);
add(primary);
}
// this is the listener
private class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
if (event.getSource() == b1) {
label1.setText("1");
}
}
}
}
Store the text that you want to print on a label in a separate instance variable (String). Every time a button is pressed, append the number to this text and set it on the label.
Simply append the result to what the label already contains
label.setText(label.getText() + "1");

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