I have one Swing project and I have an action listener on JTextField for Tab key as follows.
There is a JOptionPane.showMessageDialog() inside the action listener. And when Tab is pressed option pane will show an Information message.
My problem is that, when I press Enter on OK button of Information Message dialog, a serie of action is invoked viz Tab action of JTextField and Enter action of btnNewButton.
If I use mouse click on OK button of Error Message dialog, every thing is fine and no problem.
Can I solve this using key bindings instead of key listener?
Please suggest a solution
import java.awt.EventQueue;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Collections;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
public class Test extends JFrame {
private JPanel contentPane;
private JTextField textField;
private JButton btnNewButton;
private JDialog dialog;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Test frame = new Test();
frame.setVisible(true);
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
public Test() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
setLocationRelativeTo(null);
contentPane.setLayout(null);
textField = new JTextField();
textField.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
Collections.emptySet());
textField.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyPressed(java.awt.event.KeyEvent evt) {
if (evt.getKeyCode() == KeyEvent.VK_TAB) {
JOptionPane.showMessageDialog(dialog, " Please Press ENTER Key", "information",
JOptionPane.INFORMATION_MESSAGE);
btnNewButton.grabFocus();
}
}
});
textField.setBounds(73, 28, 178, 28);
contentPane.add(textField);
textField.setColumns(10);
btnNewButton = new JButton("New button");
btnNewButton.addKeyListener(new KeyAdapter() {
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
JOptionPane.showMessageDialog(dialog, " That Invoked New Button Also", "Error",
JOptionPane.ERROR_MESSAGE);
}
}
});
btnNewButton.setBounds(223, 137, 117, 25);
contentPane.add(btnNewButton);
JLabel lblNewLabel = new JLabel("Please Press TAB Key");
lblNewLabel.setBounds(83, 55, 183, 15);
contentPane.add(lblNewLabel);
dialog = new JDialog();
dialog.setAlwaysOnTop(true);
}
}
The problem is that you are overriding method keyReleased(). The JOptionPane is closing before the keyReleased() method is called and since you make btnNewButton the focused component after the JOptionPane is closed, the keyReleased() method is invoked – which displays the other JOptionPane.
Simply rename the method to keyPressed().
Also, you don't need the dialog member. The first parameter to JOptionPane#showMessageDialog should be the JFrame.
Here is your code with my corrections.
import java.awt.EventQueue;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Collections;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
public class Test extends JFrame {
private JPanel contentPane;
private JTextField textField;
private JButton btnNewButton;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Test frame = new Test();
frame.setVisible(true);
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
public Test() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
setLocationRelativeTo(null);
contentPane.setLayout(null);
textField = new JTextField();
textField.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
Collections.emptySet());
textField.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyPressed(java.awt.event.KeyEvent evt) {
if (evt.getKeyCode() == KeyEvent.VK_TAB) {
JOptionPane.showMessageDialog(Test.this, " Please Press ENTER Key", "information",
JOptionPane.INFORMATION_MESSAGE);
btnNewButton.grabFocus();
}
}
});
textField.setBounds(73, 28, 178, 28);
contentPane.add(textField);
textField.setColumns(10);
btnNewButton = new JButton("New button");
btnNewButton.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
JOptionPane.showMessageDialog(Test.this, " That Invoked New Button Also", "Error",
JOptionPane.ERROR_MESSAGE);
}
}
});
btnNewButton.setBounds(223, 137, 117, 25);
contentPane.add(btnNewButton);
JLabel lblNewLabel = new JLabel("Please Press TAB Key");
lblNewLabel.setBounds(83, 55, 183, 15);
contentPane.add(lblNewLabel);
}
}
Note that (at least in JDK 15) there is no need to explicitly set the default close operation for JFrame since the default is EXIT_ON_CLOSE
Related
Hi I am new in Java coding and trying to design a user friendly desktop App with the help of JFrame and JDialog -
My JFrame is -
package com.myapp.ui;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JCheckBox;
public class MyFrame extends JFrame {
private JPanel contentPane;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MyFrame frame = new MyFrame();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public MyFrame() {
setTitle("MyFrame");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JButton btnClickMe = new JButton("Click Me");
btnClickMe.setBounds(271, 171, 115, 29);
contentPane.add(btnClickMe);
JCheckBox chckbxOpenDialog = new JCheckBox("Open Dialog");
chckbxOpenDialog.setBounds(25, 171, 139, 29);
contentPane.add(chckbxOpenDialog);
chckbxOpenDialog.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(chckbxOpenDialog.isSelected()== true){
MyDialog MD = new MyDialog();
MD.setModal(true);
MD.setVisible(true);
}
}
});
btnClickMe.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//Here I want to get the value of textFieldName and textFieldEmail from JDialog
//after Click on Confirm Button in JDialog and closing/disposing it
}
});
}
}
My JDialog is -
package com.myapp.ui;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextField;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class MyDialog extends JDialog {
private final JPanel contentPanel = new JPanel();
private JTextField textFieldName;
private JTextField textFieldEmail;
private JButton btnConfirm;
public static void main(String[] args) {
try {
MyDialog dialog = new MyDialog();
dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
dialog.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
public MyDialog() {
setTitle("MyDialog");
setBounds(100, 100, 450, 300);
getContentPane().setLayout(new BorderLayout());
contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
getContentPane().add(contentPanel, BorderLayout.CENTER);
contentPanel.setLayout(null);
textFieldName = new JTextField();
textFieldName.setBounds(108, 26, 146, 26);
contentPanel.add(textFieldName);
textFieldName.setColumns(10);
textFieldEmail = new JTextField();
textFieldEmail.setBounds(108, 68, 146, 26);
contentPanel.add(textFieldEmail);
textFieldEmail.setColumns(10);
btnConfirm = new JButton("Confirm");
btnConfirm.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//passing the Name and Email field value in JFrame
}
});
btnConfirm.setBounds(132, 141, 115, 29);
contentPanel.add(btnConfirm);
MyFrame MF = new MyFrame();
}
}
Both the JFrame and JDialog are in the same package. I am trying to get the value of
textFieldName and textFieldEmail from JDialog to JFrame
if any one can guide me the best possible way, would be relly great.
You could:
Add setters to MyFrame
Pass MyFrame reference to MyDialog (using this) when it is created in the ActionListener
In the ActionListener in MyDialog set fields in MyFrame
There are probably better ways to do this. The built in JOptionPane produces modal dialog windows that wait for user input. These would be better rather than passing references of JFrames to JDialog.
Also note that JavaFX has largely replaced Java Swing for desktop UIs
I have my original text field in my first frame and I need it to be displayed in my other jframe. The code is:
JButton btnContinue = new JButton("Continue");
btnContinue.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String msg = nameL.getText();
frame2 fram = new frame2 ();
fram.setVisible(true);
frame.dispose();
new order (msg) .setVisible(true);
'nameL' is the textbox the user enters their name in.
This code describe where it should be displayed:
public order(String para){
getComponents();
JLabel lblNewLabel_1 = new JLabel("");
lblNewLabel_1.setBounds(91, 27, 254, 84);
contentPane.add(lblNewLabel_1);
lblNewLabel_1.setText(para);
this is my first class where the user inputs their name
public order(String para){
getComponents();
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JTextField;
import javax.swing.JTextArea;
import java.awt.Color;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Font;
public class frame1 {
public JFrame frame;
public JTextField nameL;
public JTextField textField_1;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
frame1 window = new frame1();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public frame1() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.getContentPane().setEnabled(false);
frame.setResizable(false);
frame.getContentPane().setBackground(Color.GRAY);
frame.setForeground(Color.WHITE);
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JButton btnContinue = new JButton("Continue");
btnContinue.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String msg = nameL.getText();
frame2 fram = new frame2 ();
fram.setVisible(true);
frame.dispose();
new order (msg) .setVisible(true);
}
}
);
btnContinue.setBounds(0, 249, 450, 29);
frame.getContentPane().add(btnContinue);
JTextArea txtrPleaseEnterYour = new JTextArea();
txtrPleaseEnterYour.setEditable(false);
txtrPleaseEnterYour.setBackground(Color.LIGHT_GRAY);
txtrPleaseEnterYour.setBounds(0, 0, 450, 32);
txtrPleaseEnterYour.setText("\tPlease enter your name and email below\n If you do not have or want to provide an email, Leave the space blank");
frame.getContentPane().add(txtrPleaseEnterYour);
JTextArea txtrEnterYourFull = new JTextArea();
txtrEnterYourFull.setEditable(false);
txtrEnterYourFull.setFont(new Font("Lucida Grande", Font.PLAIN, 15));
txtrEnterYourFull.setBackground(Color.GRAY);
txtrEnterYourFull.setText("Enter your full name");
txtrEnterYourFull.setBounds(52, 58, 166, 29);
frame.getContentPane().add(txtrEnterYourFull);
nameL = new JTextField();
nameL.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
}
);
nameL.setBackground(Color.LIGHT_GRAY);
nameL.setBounds(52, 93, 284, 26);
frame.getContentPane().add(nameL);
nameL.setColumns(10);
JTextArea txtroptionalEnterYour = new JTextArea();
txtroptionalEnterYour.setEditable(false);
txtroptionalEnterYour.setFont(new Font("Lucida Grande", Font.PLAIN, 15));
txtroptionalEnterYour.setBackground(Color.GRAY);
txtroptionalEnterYour.setText("(Optional) Enter your email");
txtroptionalEnterYour.setBounds(52, 139, 193, 29);
frame.getContentPane().add(txtroptionalEnterYour);
textField_1 = new JTextField();
textField_1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
textField_1.setBackground(Color.LIGHT_GRAY);
textField_1.setBounds(52, 180, 284, 26);
frame.getContentPane().add(textField_1);
textField_1.setColumns(10);
}
}
my second class where the text field has to be set
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.Color;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
public class order extends JFrame {
/**
*
*/
private static final long serialVersionUID = 1L;
public JPanel contentPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
order frame = new order();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public order() {
setAlwaysOnTop(false);
setTitle("Order Details // Finalization");
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setBounds(100, 100, 451, 523);
contentPane = new JPanel();
contentPane.setBackground(Color.LIGHT_GRAY);
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JButton btnNewButton = new JButton("Submit Order");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
setAlwaysOnTop(true);
JOptionPane.showMessageDialog(null, "Your Order Has Been Confirmed", "enjoy your meal", JOptionPane.YES_NO_OPTION);
}
});
btnNewButton.setBounds(164, 466, 117, 29);
contentPane.add(btnNewButton);
}
public order(String para){
getComponents();
JLabel lblNewLabel_1 = new JLabel("");
lblNewLabel_1.setBounds(91, 27, 254, 84);
contentPane.add(lblNewLabel_1);
lblNewLabel_1.setText(para);
}
}
Open both JFrames, have them listen to the EventQueue for a custom "string display" event.
Wrap the string to be displayed in a custom event.
Throw that on the event queue, allowing both the JFrames to receive the event, which they will then display accordingly.
---- Edited with an update ----
Ok, so you're a bit new to Swing, but hopefully not too new to Java. You'll need to understand sub-classing and the "Listener" design pattern.
Events are things that Components listen for. They ask the dispatcher (the Swing dispatcher is fed by the EventQueue) to "tell them about events" and the dispatcher then sends the desired events to them.
Before you get too deep in solving your problem, it sounds like you need to get some familiarity with Swing and its event dispatch, so read up on it here.
I'm having a problem with my About Frame class. I call it through an action listener in a JMenuItem. It comes up but it doesn't show it centered and the frame doesn't show the icon image as I request. I have the icon working in the mainframe so it's the image size isn't the problem. Does this have something to do with the private JPanel contentPane;?
Code in the JmenuItem:
aboutMItem.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(ActionEvent e) {
jAboutMN_actionPerformed(e);
About Frame code:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
import java.awt.Font;
import java.awt.GridLayout;
import javax.swing.BoxLayout;
public class AboutFrame extends JFrame {
private JPanel contentPane;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
AboutFrame frame = new AboutFrame();
frame.setIconImage(new ImageIcon("resources/Image.png").getImage());
frame.setVisible(true);
//frame.setLocationRelativeTo(null);
frame.setLocationRelativeTo(null);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public AboutFrame() {
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
//AboutFrame.setLocationRelativeTo(null);
setTitle("About MyAPP");
setBounds(100, 100, 370, 250);
//contentPane.setLocationRelativeTo(null);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel lbVerNum = new JLabel("MYAPP, Beta 1.2");
lbVerNum.setBounds(57, 11, 233, 19);
lbVerNum.setVerticalAlignment(SwingConstants.TOP);
lbVerNum.setFont(new Font("Tahoma", Font.BOLD, 15));
lbVerNum.setHorizontalAlignment(SwingConstants.CENTER);
contentPane.add(lbVerNum);
JLabel lbCopyright = new JLabel("Copyright 2015 ");
lbCopyright.setBounds(86, 41, 170, 16);
lbCopyright.setIcon(null);
lbCopyright.setFont(new Font("Tahoma", Font.PLAIN, 13));
lbCopyright.setVerticalAlignment(SwingConstants.TOP);
lbCopyright.setHorizontalAlignment(SwingConstants.CENTER);
contentPane.add(lbCopyright);
}
}
So what I've got is that I would love to try and make an little login applet. I'm using Java Windowsbuilder for it, to make it easyer for me. I hope the code isn't to messy, because I'm just a starter.
The problem I've got is that My JButton "login" only registers a keyevent when it's selected trought tab, or when you first click it. What I want is that I can use the button always just by pressing the "ENTER" key.
Hope you guys solve my problem :)
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import org.eclipse.wb.swing.FocusTraversalOnArray;
import java.awt.Component;
import java.awt.event.KeyAdapter;
public class nummer1 extends JFrame{
private JPanel contentPane;
public static nummer1 theFrame;
private JTextField textFieldUsername;
private JTextField textFieldPass;
private nummer1 me;
private JLabel lblCheck;
private String password = "test", username = "test";
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
nummer1 frame = new nummer1();
nummer1.theFrame = frame;
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public void Check(){
String Pass = textFieldPass.getText();
String Username = textFieldUsername.getText();
System.out.println(Pass);
if (Pass.equals(password) && Username.equals(username)){
lblCheck.setText("Correct Login");
}else{
lblCheck.setText("Invalid username or password");
}
}
/**
* Create the frame.
*/
public nummer1() {
me = this;
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 356, 129);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel lblUsername = new JLabel("Username:");
lblUsername.setBounds(10, 11, 61, 14);
contentPane.add(lblUsername);
JLabel lblPassword = new JLabel("Password:");
lblPassword.setBounds(10, 36, 61, 14);
contentPane.add(lblPassword);
textFieldUsername = new JTextField();
textFieldUsername.setBounds(81, 8, 107, 20);
contentPane.add(textFieldUsername);
textFieldUsername.setColumns(10);
me.textFieldUsername = textFieldUsername;
textFieldPass = new JTextField();
textFieldPass.setBounds(81, 33, 107, 20);
contentPane.add(textFieldPass);
textFieldPass.setColumns(10);
me.textFieldPass = textFieldPass;
JButton btnLogin = new JButton("Login");
contentPane.requestFocusInWindow();
btnLogin.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_ENTER){
me.Check();
System.out.println("hi");
}
}
});
btnLogin.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
me.Check();
}
});
btnLogin.setBounds(198, 7, 89, 23);
contentPane.add(btnLogin);
JLabel lblCheck = new JLabel("");
lblCheck.setHorizontalAlignment(SwingConstants.TRAILING);
lblCheck.setBounds(10, 65, 264, 14);
contentPane.add(lblCheck);
me.lblCheck = lblCheck;
contentPane.setFocusTraversalPolicy(new FocusTraversalOnArray(new
Component[]{lblUsername, lblPassword, textFieldUsername, textFieldPass, btnLogin, lblCheck}));
}
}
Thanks Emil!
What I want is that I can use the button always just by pressing the "ENTER" key
Sounds like you want to make the "login" button the default button for the dialog.
See Enter Key and Button for the problem and solution.
When using panels KeyListeners won't work unless the panel is focusable. What you can do is make a KeyBinding to the ENTER key using the InputMap and ActionMap for your panel.
public class Sample extends JPanel{
//Code
Sample() {
//More code
this.getInputMap().put(KeyStroke.getKeyStroke((char)KeyEvent.VK_ENTER), "Enter" );
this.getActionMap().put("Enter", new EnterAction());
}
private class EnterAction extends AbstractAction(){
#Override
public void ActionPerformed(ActionEvent e){
//Acion
}
}
}
I am trying to program an 'Inch-to-Centimeter Calculator'. I've got a problem with the method umrechnen(). The label lblCenti cannot be resolved. My Code is equal to the Solutioncode. I am grateful for every answer or tip I get.
I don't know what I should add to my Description, but StackOverflow forces me to write more, so I'm writing this.
package gui;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.text.DecimalFormat;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class ZollZentimeter extends JFrame {
private JPanel contentPane;
private JTextField tfInch;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ZollZentimeter frame = new ZollZentimeter();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public ZollZentimeter() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 359, 157);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JButton btnCalculate = new JButton("Umrechnen");
btnCalculate.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
umrechnen();
}
});
btnCalculate.setBounds(12, 77, 116, 25);
contentPane.add(btnCalculate);
JButton btnEnde = new JButton("Ende");
btnEnde.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
btnEnde.setBounds(214, 77, 116, 25);
contentPane.add(btnEnde);
JLabel lblZoll = new JLabel("Zoll");
lblZoll.setBounds(12, 13, 56, 16);
contentPane.add(lblZoll);
tfInch = new JTextField();
tfInch.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if(e.getKeyCode()==KeyEvent.VK_ENTER){
umrechnen();
}
}
});
JLabel lblCenti = new JLabel("");
lblCenti.setBounds(214, 42, 116, 22);
contentPane.add(lblCenti);
tfInch.setBounds(12, 42, 116, 22);
contentPane.add(tfInch);
tfInch.setColumns(10);
}
private void umrechnen(){
DecimalFormat f=new DecimalFormat("#0.00");
double z, cm;
z=Double.parseDouble(tfInch.getText());
cm=z*2.54;
lblCenti.setText(f.format(cm+" cm"));
tfInch.requestFocus();
tfInch.selectAll();
}
}
JLabel lblCenti = new JLabel("");
"lblCenti" is defined as a local variable so it can only be accessible in the method/constructor where you define it.
It you want to access the label in another method you need to define it as an instance variable, the same way you do with the "tfInch" variable.