I am building a Java GUI on IntelliJ and making an 'exit' button - currently using
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
public class gui extends JFrame {
private JPanel mainPanel;
private JButton exitButton;
public gui(String title) {
super(title);
exitButton = new JButton("Exit");
exitButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setContentPane(mainPanel);
this.pack();
}
public static void main(String[] args) {
JFrame frame = new gui("Emro GUI");
frame.setVisible(true);
}
}
The code runs, and I followed an exact tutorial on youtube, but the exit button isn't function how it should and I am unsure why. Should I have the exit button in a new class or function?
Adding the following three lines in appropriate locations will make it work.
import javax.swing.*;
mainPanel = new JPanel();
mainPanel.add(exitButton);
However:
Swing should always be used from the AWT Event Dispatch Thread (EDT) (use java.awt.EventQueue.invokeLater.
No need to extend JFrame.
No need for mainPanel and exitButton to be fields instead of locals.
Use a lambda expression for the ActionListener.
Have you tried this inside your action listeners method:
WindowEvent closeWindowEvent = new WindowEvent(frame, WindowEvent.WINDOW_CLOSING); frame.dispatchEvent(closeWindowEvent);
Related
What's wrong? ImageIcon and the frame's size are working properly.
But the JTextField and the JButton aren't.
I need the solution.
import javax.swing.*;
import javax.swing.ImageIcon;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Frame {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("Alkalmazás");
frame.setVisible(true);
frame.setSize(500,500);
frame.setResizable(false);
JTextField field = new JTextField();
field.setBounds(40,250, 300,35);
JButton button = new JButton(new ImageIcon("table.png"));
button.setBounds(40,400, 250,25);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
tf.setText(""something);
}
});
frame.add(field);
frame.add(button);
}
}
You didn't mention what's "not working properly", but there are a few errors with your code:
Don't call your class Frame, it may confuse you or others about java.awt.Frame, something that may work would be MyFrame
Right now all your class is inside the main method and it's not placed inside the Event Dispatch Thread (EDT), to fix this, create an instance of your class and call a method createAndShowGUI (or whatever you want to name it) inside SwingUtilities.invokeLater()
For Example:
public static void main(String args[]) {
SwingUtilities.invokeLater(new MyFrame()::createAndShowGUI)
}
Or if using Java 7 or lower, use the code inside this answer in point #2.
setVisible(true) should be the last line in your code, otherwise you may find some visual glitches that may be resolved until you move your mouse above your window or something that triggers the call to repaint() of your components.
Instead of calling setSize(...) directly, you should override getPreferredSize(...) of your JPanel and then call pack() on your JFrame, see this question and the answers in it: Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?
You're adding 2 components to the CENTER of BorderLayout, which is a JFrame's default layout manager, there are other layout managers and you can combine them to make complex GUI's.
setBounds(...) might mean that you're using null-layout, which might seem like the easiest way to create complex layouts, however you will find yourself in situations like this one if you take that approach, it's better to let Swing do the calculations for you while you use layout managers. For more, read: Why is it frowned upon to use a null layout in Swing?
With all the above tips now in mind, you may have a code similar to this one:
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class MyFrame {
private JFrame frame;
private JPanel pane;
private JTextField field;
private JButton button;
public static void main(String[] args) {
SwingUtilities.invokeLater(new MyFrame()::createAndShowGUI);
}
private void createAndShowGUI() {
frame = new JFrame("Alkalmazás");
pane = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
};
pane.setLayout(new BoxLayout(pane, BoxLayout.PAGE_AXIS));
field = new JTextField(10);
button = new JButton("Click me");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
field.setText("something");
}
});
pane.add(field);
pane.add(button);
frame.add(pane);
frame.setResizable(false);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Now you have an output similar to this one:
What about you want the JTextField to have a more "normal" size? Like this one:
You'll have to embed field inside another JPanel (with FlowLayout (the default layout manager of JPanel)), and then add that second JPanel to pane, I'm not writing the code for that as I'm leaving that as an exercise to you so you learn how to use multiple layout managers
How do I solve this compilation error? Note that I'm new to Swing.
http://prntscr.com/bpz2ve
package gui;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
public class GUI extends Frame {
public static void main(String[] args) {
JFrame frame = new JFrame("Hello World - YaBoiAce");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(500, 300);
// Layout //
frame.setLayout(new BorderLayout());
// Swing Component //
final JTextArea textarea = new JTextArea();
JButton jbutton = new JButton("Click me");
// Add Component to content pane
Container c = frame.getContentPane();
c.add(textarea,BorderLayout.CENTER);
c.add(jbutton, BorderLayout.SOUTH);
// Action Listener
jbutton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
textarea.append("Hello");
} // Eclipse says 'missing ;' on this line.
}
private static void setDefaultCloseOperation(int exitOnClose) {
}
}
Eclipse says "Missing ;" But when I put that in, It highlights the ; saying "Missing ;" again. It keeps on doing that. Any help?
It is on the line marked with:
// Eclipse says 'missing ;' on this line.
There are many problems in your code:
As stated in the
comments
by #HovercraftFullOfEels:
You're not matching closing parenthesis on your addActionListener method too. Again good code formatting will help you see this.
// Action Listener
jbutton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
textarea.append("Hello");
} // Eclipse says 'missing ;' on this line.
}); //HERE YOU NEED TO ADD: );
You're extending Frame (Maybe you were trying to extend JFrame)
and creating a JFrame object, choose which one you want to use
(Recommended to create the object instead of extending, because if
you extend a JFrame your class is a JFrame and cannot be
included somewhere else and you're not changing it's functionallity
either so, no need to extend).
You're creating a private static method
private static void setDefaultCloseOperation(int exitOnClose) {}
That method should be public and belongs to JFrame class, I guess your IDE wrote that when you extended Frame instead of JFrame.
Frame belongs to java.awt while JFrame belongs to javax.swing so, they are not the same.
You're creating your windows and every component inside your main
method instead of the constructor
You're adding your components to a Container but never add that container to your JFrame, so you need to call
frame.setContentPane(c);
So your code should look like this:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class GUI {
JFrame frame;
public GUI() {
frame = new JFrame("Hello World - YaBoiAce");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(500, 300);
// Layout //
frame.setLayout(new BorderLayout());
// Swing Component //
final JTextArea textarea = new JTextArea();
JButton jbutton = new JButton("Click me");
frame.add(textarea,BorderLayout.CENTER);
frame.add(jbutton, BorderLayout.SOUTH);
// Add Component to content pane
Container c = frame.getContentPane();
c.add(textarea,BorderLayout.CENTER);
c.add(jbutton, BorderLayout.SOUTH);
frame.setContentPane(c);
// Action Listener
jbutton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
textarea.append("Hello");
} // Eclipse says 'missing ;' on this line.
});
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new GUI());
}
}
I have a program which displays two buttons and changes the image of one of the buttons on roll over. I am getting an error on my
press.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
part, And it looks like this: The method setDefaultCloseOperation(int) is undefined for the type ButtonClass. Even with the exit on close commented out there are more errors, please help.
Main class (with error):
package Buttons;
import javax.swing.JFrame;
public class Main_buttons{
public static void main(String[] args) {
ButtonClass press = new ButtonClass();
press.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
press.setSize(300,200);
press.setVisible(true);
}
}
ButtonClass class:
package Buttons;
import java.awt.FlowLayout; //layout proper
import java.awt.event.ActionListener; //Waits for users action
import java.awt.event.ActionEvent; //Users action
import javax.swing.JFrame; //Window
import javax.swing.JButton; //BUTTON!!!
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JOptionPane; //Standard dialogue box
public class ButtonClass extends JButton {
private JButton regular;
private JButton custom;
public ButtonClass() { // Constructor
super("The title"); // Title
setLayout(new FlowLayout()); // Default layout
regular = new JButton("Regular Button");
add(regular);
Icon b = new ImageIcon(getClass().getResource("img.png"));
Icon x = new ImageIcon(getClass().getResource("swag.png"));
custom = new JButton("Custom", b);
custom.setRolloverIcon(x); //When you roll over the button that says custom the image will change from b to x
add(custom);
Handlerclass handler = new Handlerclass();
regular.addActionListener(handler);
custom.addActionListener(handler);
}
private class Handlerclass implements ActionListener { // This class is inside the other class
public void actionPerformed(ActionEvent eventvar) { // This will happen
// when button is
// clicked
JOptionPane.showMessageDialog(null, String.format("%s", eventvar.getActionCommand()));//Opens a new window with the name of the button
}
}
}
I have searched everywhere for this problem and found nothing. Please tell me how to resolve this issue about exiting my window.
Thanks!
You're a little confused as you're creating a class that extends JButton, and calling setVisible(true) on it as if it were a top-level window such as a JFrame or JDialog, and that doesn't make sense. Since it isn't a top-level window it also makes sense to not have a default close operation or understand what that means.
I suggest that you call this method only on top-level windows such as on a JFrame or JDialog and the like. As a side recommendation, I usually avoid setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); and instead more often do setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); which gives it a little more flexibility.
Edit: actually, just change your class to extends JFrame not extends JButton.
Make sure your image path to your resources is correct. For example:
that method is defined for JFrame, not JButton. You're calling it on an instance of a class that extends JButton
The JFrame.Exit_on_close must be used in a JFrame, and you are extending from JButton.
To set a JButton to close a JFrame its something like this.
public class MyClass extends JFrame implements ActionListener{
private JButton button = new JButton("Button");
private JPanel panel = new JPanel();
public static void main(String args[]) {
new MyClass();
}
public MyClass() {
setSize(300, 300);
button.addActionListener(this);
panel.add(button);
add(panel);
setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
this.dispose();
}
}
I'm trying to dispose of the difficulty window after any one of the difficulty button's are clicked but it won't happen. I've tried .dispose and frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); but i can't get it. Is it just placement or more?
import java.awt.FlowLayout;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.GridLayout;
public class Game extends JFrame{
public static JFrame frame = new JFrame();
private JLabel lab;
public static void main(String[] args) {
Game difficulty = new Game();
difficulty.setSize(350,105);
difficulty.setTitle("Difficulty.");
difficulty.setVisible(true);
difficulty.setLocationRelativeTo(null);
/**Game sudoku = new Game();
sudoku.setSize(900, 900);
sudoku.setVisible(false);*/
}
public Game(){
setLayout(new FlowLayout());
lab = new JLabel("Please select your difficulty.");
add(lab);
JButton easy;
easy = new JButton("Easy");
add(easy);
easy.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
//Execute when button is pressed
System.out.println("You clicked the button");
JFrame.dispose();
}
});
JButton medium;
medium = new JButton("Medium");
add(medium);
JButton hard;
hard = new JButton("Hard");
add(hard);
JButton evil;
evil = new JButton("Evil!");
add(evil);
}
}
First of all you're extending JFrame and creating an object of JFrame, if I'm not wrong, this shouldn't be done.
public class Game extends JFrame{
public static JFrame frame = new JFrame();
And as #Salah said, JFrame is not static, so it should be:
public JFrame frame = new JFrame();
To solve your problem, you're disposing a new JFrame (yes, you have 3 JFrames in one class, instead of 1, which is what you want), with: JFrame.dispose(); if you already created an object or you're extending JFrame, you can:
this.dispose(); //For the extended JFrame
or
frame.dispose(); //For the object you created
dispose() method is not a static, so it'll not work by calling it directly from JFrame class
JFrame.dispose();
try to do :
dispose();
Or to dispose the frame object you have created
frame.dispose();
Read more about JFrame
I had the same problem:
this.dispose();
solved my problem.
Try setting the jFrame to invisible before disposing it:
public void disposeJFrame(JFrame frame){
frame.setVisible(false);
frame.dispose();
}
If you're wanting to close the whole program, you can use System.exit(0);
Instead JFrame.dispose();, use frame.dispose() or JFrame.this.dispose();
As of late I've been developing a (very) small GUI application in Java. I'm extremely new to Swing and Java in general, but up until now I have been able to get everything to work the way I want it to. However, after cleaning up my code, when I run the program nothing but the border of the window appears. What am I doing wrong and how can I fix my code? Thanks ahead of time!
For the sake of saving space I've made Pastebin links to all of my classes (besides Main).
Main Class
package me.n3rdfall.ezserver.main;
public class Main {
public static GUI g = new GUI();
public static void main(String[] args) {
g.showWindow(800, 500);
}
}
GUI Class
http://pastebin.com/gDMipdp1
ButtonListener Class
http://pastebin.com/4XXm70AD
EDIT: It appears that calling removeAll() directly on 'frame' actually removed essential things other than what I had added. By calling removeAll() on getContentPane(), the issue was resolved.
Quick hack: Remove the removeAll() functions.
public void homePage() {
// frame.removeAll();
// mainpanel.removeAll();
// topbar.removeAll();
I'm not sure what you're trying to achieve, but that will at least show some items. If I were you I would rebuild this GUI by extending JFrame. It will make your code a little easier to read.
I also think what you are trying to achieve with the buttons is to switch layouts, you can do this in an easier way by using CardLayout
Example (has nothing to do with your code, but to demonstrate):
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Example extends JFrame implements ActionListener {
private JButton leftButton;
private JButton rightButton;
private CardLayout cardLayout = new CardLayout();
JPanel cards = new JPanel(cardLayout);
final static String LEFTPANEL = "LEFTPANEL";
final static String RIGHTPANEL = "RIGHTPANEL";
JPanel card1;
JPanel card2;
public Example() {
JPanel topPanel = new JPanel();
addButtons(topPanel);
add(topPanel, BorderLayout.NORTH);
add(cards, BorderLayout.CENTER);
//Initiates the card panels
initCards();
setTitle("My Window");
setSize(300, 300);
setLocationRelativeTo(null);
setVisible(true);
}
private void initCards() {
card1 = new JPanel();
card2 = new JPanel();
card1.setBackground(Color.black);
card2.setBackground(Color.red);
cards.add(card1, LEFTPANEL);
cards.add(card2, RIGHTPANEL);
}
private void addButtons(Container con) {
leftButton = new JButton("Left Button");
leftButton.addActionListener(this);
rightButton = new JButton("Right Button");
rightButton.addActionListener(this);
con.add(leftButton, BorderLayout.WEST);
con.add(rightButton, BorderLayout.EAST);
}
#Override
public void actionPerformed(ActionEvent e) {
if(e.getSource().equals(leftButton)) {
//Change cardlayout
cardLayout.show(cards, LEFTPANEL);
} else if(e.getSource().equals(rightButton)) {
//Change cardlayout
cardLayout.show(cards, RIGHTPANEL);
}
}
public static void main(String[] args) {
new Example();
}
}