Develop Reference

How do you close a JFrame window without closing another one?

I am new to Java Swing and I am trying to learn how to close one frame without closing the other one using button. For example I have a frame1/window that just have a button called login. Once I click on login button, another window appear frame2. On frame2 I just have a sample JLabel "Hello And Welcome", button called Logout. I want to be able to click on the Logout button on frame2 and frame2 window should close, but frame1 window show still be open. I have try setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE), but it only work if I click on the x icon on the top right of the frame2 window. Does anyone know of a way to close a frame when you click on a button?
public class Frame1 extends JFrame implements ActionListener{
private static JButton login = new JButton("Login");
private static JFrame f = new JFrame("Login");
Frame1(){
f.setSize(1000,750);
f.setLocation(750, 250);
login.setBounds(250, 350, 150, 30);
f.add(login);
f.setLayout(null);
f.setVisible(true);
login.addActionListener(this);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e){
if (e.getSource() == login){
Frame2.frame2windown();
}
}
public static void main(String [] args){
Frame1 login1 = new Frame1();
}
}
public class Frame2 extends JFrame implements ActionListener{
private static JButton logout = new JButton("Logout");
private static JLabel jb1 = new JLabel ("Hello And Welcome");
private static JFrame f = new JFrame("Log Out");
Frame2(){
f.setSize(1000,750);
f.setLocation(750, 250);
jb1.setBounds(250, 150, 350, 30);
logout.setBounds(250, 350, 150, 30);
f.add(logout);
f.add(jb1);
f.setLayout(null);
f.setVisible(true);
logout.addActionListener(this);
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
public void actionPerformed(ActionEvent a){
if(a.getSource() == logout){
dispose();
WindowEvent closeWindow = new WindowEvent(this, JFrame.DISPOSE_ON_CLOSE);
Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(closeWindow);
}
}
public static void frame2windown(){
Frame2 f2 = new Frame2();
}
}

So, there are a whole bunch of concepts your need to try and learn.
It's generally recommended NOT to extend from top level containers (like JFrame). You're not adding any new functionality too them; they are complicated, compound components; you lock yourself into a single use case (what happens if you want to include the UI in another UI or use a dialog instead of frame?!)
Multiple frames aren't always a good idea and can be confusing to the user. Generally, with login workflows though, I might argue a login dialog is generally a better solution, but you need to understand the use cases to make those determinations.
Swing is a large, rich and diverse API, it has a LOT of inbuilt functionality, which you can use, to make your life easier (although it doesn't always seem this way)
Layout managers are an absolutely required feature and you really need to take the time to learn them, see Laying Out Components Within a Container for more details.
So, a really quick example of using a CardLayout and a basic "observer pattern", which decouples and separates responsibility.
import java.awt.CardLayout;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.EventListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new NavigationPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class NavigationPane extends JPanel {
protected enum NavigationTarget {
LOGIN, MAIN;
}
private LoginPane loginPane;
private MainPane mainPane;
private CardLayout cardLayout;
public NavigationPane() {
cardLayout = new CardLayout();
setLayout(cardLayout);
loginPane = new LoginPane();
loginPane.addLoginListener(new LoginPane.LoginListener() {
#Override
public void loginDidFail(LoginPane source) {
JOptionPane.showMessageDialog(NavigationPane.this, "You are not unauthroised", "Error", JOptionPane.ERROR_MESSAGE);
}
#Override
public void loginWasSuccessful(LoginPane source) {
navigateTo(NavigationTarget.MAIN);
}
});
mainPane = new MainPane();
add(loginPane, NavigationTarget.LOGIN.name());
add(mainPane, NavigationTarget.MAIN.name());
navigateTo(NavigationTarget.LOGIN);
}
protected void navigateTo(NavigationTarget target) {
cardLayout.show(this, target.name());
}
}
public static class LoginPane extends JPanel {
public static interface LoginListener extends EventListener {
public void loginDidFail(LoginPane source);
public void loginWasSuccessful(LoginPane source);
}
public LoginPane() {
setBorder(new EmptyBorder(10, 10, 10, 10));
setLayout(new GridBagLayout());
JButton btn = new JButton("Login");
btn.addActionListener(new ActionListener() {
private Random rnd = new Random();
#Override
public void actionPerformed(ActionEvent e) {
// Do some logic here
if (rnd.nextBoolean()) {
fireLoginWasSuccessful();
} else {
fireLoginDidFail();
}
}
});
add(btn);
}
public void addLoginListener(LoginListener listener) {
listenerList.add(LoginListener.class, listener);
}
public void removeLoginListener(LoginListener listener) {
listenerList.remove(LoginListener.class, listener);
}
protected void fireLoginDidFail() {
LoginListener[] listeners = listenerList.getListeners(LoginListener.class);
for (LoginListener listener : listeners) {
listener.loginDidFail(this);
}
}
protected void fireLoginWasSuccessful() {
LoginListener[] listeners = listenerList.getListeners(LoginListener.class);
for (LoginListener listener : listeners) {
listener.loginWasSuccessful(this);
}
}
}
public static class MainPane extends JPanel {
public MainPane() {
setLayout(new GridBagLayout());
setBorder(new EmptyBorder(10, 10, 10, 10));
add(new JLabel("Welcome"));
}
}
}
JDialog based login workflow
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
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.SwingUtilities;
import javax.swing.border.EmptyBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
NavigationPane navigationPane = new NavigationPane();
JFrame frame = new JFrame();
frame.add(navigationPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
if (LoginPane.showLoginDialog(navigationPane)) {
navigationPane.didLogin();
} else {
frame.dispose();
}
}
});
}
public static class NavigationPane extends JPanel {
protected enum NavigationTarget {
SPLASH, MAIN;
}
private SplashPane splashPane;
private MainPane mainPane;
private CardLayout cardLayout;
public NavigationPane() {
cardLayout = new CardLayout();
setLayout(cardLayout);
mainPane = new MainPane();
splashPane = new SplashPane();
add(splashPane, NavigationTarget.SPLASH.name());
add(mainPane, NavigationTarget.MAIN.name());
navigateTo(NavigationTarget.SPLASH);
}
protected void navigateTo(NavigationTarget target) {
cardLayout.show(this, target.name());
}
public void didLogin() {
navigateTo(NavigationTarget.MAIN);
}
}
public static class LoginPane extends JPanel {
private Random rnd = new Random();
private boolean isAuthorised = false;
public LoginPane() {
setBorder(new EmptyBorder(10, 10, 10, 10));
setLayout(new GridBagLayout());
add(new JLabel("User name and password fields go here"));
}
protected void authenticate() {
// Authenticate
isAuthorised = rnd.nextBoolean();
if (!isAuthorised) {
JOptionPane.showMessageDialog(this, "You are not authorised", "Error", JOptionPane.ERROR_MESSAGE);
}
}
// So this should return some kind of "session" or something so
// can identify the user, but for now, we'll just use
// a boolean
public boolean isAuthorised() {
return isAuthorised;
}
public static boolean showLoginDialog(Component parent) {
LoginPane loginPane = new LoginPane();
JPanel panel = new JPanel(new BorderLayout());
JPanel buttonPane = new JPanel(new GridBagLayout());
JButton okayButton = new JButton("Login");
JButton cancelButton = new JButton("Cancel");
buttonPane.add(okayButton);
buttonPane.add(cancelButton);
panel.add(loginPane);
panel.add(buttonPane, BorderLayout.SOUTH);
JDialog dialog = new JDialog(SwingUtilities.windowForComponent(parent));
dialog.add(panel);
okayButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
loginPane.authenticate();
if (loginPane.isAuthorised()) {
dialog.dispose();
}
}
});
cancelButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
dialog.dispose();
}
});
dialog.setModal(true);
dialog.pack();
dialog.setLocationRelativeTo(parent);
dialog.setVisible(true);
return loginPane.isAuthorised();
}
}
public static class SplashPane extends JPanel {
public SplashPane() {
setLayout(new GridBagLayout());
setBorder(new EmptyBorder(10, 10, 10, 10));
add(new JLabel("This is a splash panel, put some nice graphics here"));
}
}
public static class MainPane extends JPanel {
public MainPane() {
setLayout(new GridBagLayout());
setBorder(new EmptyBorder(10, 10, 10, 10));
add(new JLabel("Welcome"));
}
}
}

You duplicated the JFrame, created a JFrame field f inside the JFrame.
Do not use static components like the button.
public class Frame1 extends JFrame implements ActionListener {
private final JButton login = new JButton("Login");
Frame1() {
setTitle("Login");
setSize(1000, 750);
setLocation(750, 250);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(null);
login.setBounds(250, 350, 150, 30);
add(login);
login.addActionListener(this);
setVisible(true);
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == login) {
Frame2.frame2windown();
}
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
Frame1 login1 = new Frame1();
}
}
}
Use the swing/awt event queue (invokeLater) as on this thread window events are handled and dispatched further.
And Frame2:
public class Frame2 extends JFrame implements ActionListener {
private JButton logout = new JButton("Logout");
private JLabel jb1 = new JLabel("Hello And Welcome");
Frame2() {
setTitle("Logout");
setSize(1000, 750);
setLocation(750, 250);
setLayout(null);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
jb1.setBounds(250, 150, 350, 30);
logout.setBounds(250, 350, 150, 30);
add(logout);
add(jb1);
logout.addActionListener(this);
setVisible(true);
}
public void actionPerformed(ActionEvent a) {
if (a.getSource() == logout) {
setVisible(false); // <--- ALL
}
}
public static void frame2windown() {
Frame2 f2 = new Frame2();
}
}
JFrame.setVisible does it all. Especially setVisible(true) should maybe even done after the constructor is called, so it always is last.
Another remark, dive into layout managers fast. Absolute layouts (null) are a PITA.

I can't change the color of a JButton when pressed

I have all the imports needed and there are no errors but it won't work.
final JButton button_32 = new JButton("2");
button_32.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
button_32.setBackground(Color.red);
}
});
button_32.setBounds(0, 57, 33, 29);
contentPane.add(button_32);

You can create your own Button, which extends ButtonModel or just do it, as suggested here.

public class Main {
static JFrame frame;
public static void main(String[] args)
{
// schedule this for the event dispatch thread (edt)
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
displayJFrame();
}
});
}
static void displayJFrame()
{
frame = new JFrame("Our JButton listener example");
// create our jbutton
final JButton showDialogButton = new JButton("Click Me");
// add the listener to the jbutton to handle the "pressed" event
showDialogButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
// when the button is pressed
showDialogButton.setBackground(Color.RED);
}
});
// put the button on the frame
frame.getContentPane().setLayout(new FlowLayout());
frame.add(showDialogButton);
// set up the jframe, then display it
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(300, 200));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}

I think it can be related to "implementation of the abstract class".
Try this:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class ExamButton extends JFrame {
JButton button_32 = new JButton("ssf");
JFrame frame = new JFrame();
public ExamButton() {
final JButton button_32 = new JButton("2");
button_32.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
button_32.setBackground(Color.red);
}
});
button_32.setBounds(0, 57, 33, 29);
add(button_32, BorderLayout.CENTER);
setSize(300, 300);
setVisible(true);
}
public static void main(String[] args) {
new ExamButton();
}
}

rectangular component disappears upon resizing the frame

I have a following code ( trying to learn swing and java). I created a ladder using rectangular components using class and placed on the main frame. Everything works okay but if I resize it even slightly, the ShapeManager object (i.e, the ladder) disappears. I don't know what is going on. Any help please.
GUIMain Class:
package mainProg;
import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.event.*;
import java.awt.*;
public class GUIMain {
static JPanel mainPanel;
static JButton[] newButtons;
static ShapeManager newShape;
private static class BtnEvtHandler implements ActionListener {
public void actionPerformed(ActionEvent e) {
//System.exit(0);
JOptionPane.showMessageDialog( null, "WELCOME" );
}
}
private static JButton[] createButtons() {
JButton[] buttonArray= new JButton[2];
buttonArray[0]=new JButton("OK");
buttonArray[1]=new JButton("MOVE");
BtnEvtHandler okButtonHandler= new BtnEvtHandler();
( buttonArray[0]).addActionListener(okButtonHandler);
return buttonArray;
}
private static ShapeManager createShape(int x) {
ShapeManager newContent=new ShapeManager(x);
return newContent;
}
private static JPanel mainContainer() {
JPanel mainPanel= new JPanel();
mainPanel.setSize(400, 400);
return mainPanel;
}
private static void createAndShowGUI() {
JFrame.setDefaultLookAndFeelDecorated(false);
JFrame frame = new JFrame(" DB ");
mainPanel= mainContainer();
mainPanel.setLayout(new BorderLayout(10, 10));
newButtons= createButtons();
newShape= createShape(20);
newButtons[0].setHorizontalAlignment(0);
mainPanel.add(newButtons[0],BorderLayout.PAGE_START);
newButtons[1].setHorizontalAlignment(0);
mainPanel.add(newButtons[1],BorderLayout.PAGE_END);
newShape.setPreferredSize(new Dimension(400, 400));
mainPanel.add(newShape, BorderLayout.LINE_END);
frame.setContentPane(mainPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600, 600);
frame.setLocation(500,200);
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
ShapeManager Class:
package mainProg;
import javax.swing.JPanel;
import java.awt.*;
#SuppressWarnings("serial")
class ShapeManager extends JPanel {
int rectPos;
ShapeManager(int rectPos) {
setPreferredSize(new Dimension(400,400));
this.rectPos=rectPos;
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
while (rectPos<150) {
g.setColor(Color.BLUE);
g.drawRect(rectPos+10, rectPos+10, 100, 10);
g.fillRect(rectPos+10, rectPos+10, 100, 10);
rectPos=rectPos+10;
}
}
}

You never reset rectangle position, so after the first paint it remains above 150. You need to reset it after you exit your while loop.
Try this:
g.setColor(Color.BLUE);
int position = rectPos;
while (position<150) {
position += 10;
g.drawRect(position, position, 100, 10);
g.fillRect(position, position, 100, 10);
}

Events on a JPanel which has a Border Layout

When I add a MouseListener/FocusListener to a JPanel which has a BorderLayout and JComponents in it, I can't catch mouse or focus events. Is there any way to catch a JPanel's mouse and focus events which has a BorderLayout?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Application extends JFrame{
public Application(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel jPanel = new JPanel(new BorderLayout());
jPanel.add(new JButton("Button"));
jPanel.addMouseListener(new MouseAdapter() {
#Override
public void mouseExited(MouseEvent e) {
System.out.println("mouseExited");
}
});
// if border is set then listener works if not does not
// jPanel.setBorder(new LineBorder(Color.black, 1));
setLayout(new FlowLayout());
add(jPanel);
setSize(400, 400);
setVisible(true);
}
public static void main(String[]args){
new Application().setVisible(true);
}
}

As said, just a simple mistake. Because JFrame is given a FlowLayout, the JPanel occupies the area required for JButton only. You can test that by adding a Border to the JPanel.
Now it works,
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Application extends JFrame {
private static final long serialVersionUID = 1L;
public Application() {
JPanel jPanel = new JPanel();
jPanel.setLayout(new FlowLayout());
jPanel.add(new JButton("Button"));
jPanel.addMouseListener(new MouseAdapter() {
#Override
public void mouseExited(MouseEvent e) {
System.out.println("mouseExited");
}
});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
add(jPanel);
setSize(400, 400);
setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Application().setVisible(true);
}
});
}
}

The following Code prints the corresponding Events to StdOut.
JFrame frame = new JFrame();
JPanel panel = new JPanel(new BorderLayout());
JPanel innerPanel = new JPanel();
innerPanel.setSize(200,200);
panel.add(innerPanel);
panel.addMouseListener(new MouseListener() {
public void mouseReleased(MouseEvent e) {
System.out.println("MouseReleased");
}
public void mousePressed(MouseEvent e) {
System.out.println("MousePressed");
}
public void mouseExited(MouseEvent e) {
System.out.println("MouseExited");
}
public void mouseEntered(MouseEvent e) {
System.out.println("MouseEntered");
}
public void mouseClicked(MouseEvent e) {
System.out.println("MouseClicked");
}
});
frame.setContentPane(panel);
frame.setVisible(true);`

why does my button not appear on my JPanel - Java

Or maybe my JPanel is not appearing at all.
I am trying to have a JPanel at the bottom of the screen that hold several buttons. Can someone set me strait?
public class MyAWTMenu extends java.awt.Frame// implements ActionListener
{
public void init() {
setBackground( Color.white );
JPanel bottom = new JPanel();
bottom.setBackground(Color.BLACK);
JButton b1 = new JButton("test");
b1.setVisible(true);
bottom.add(b1);
bottom.setVisible(true);
add(bottom,BorderLayout.CENTER);
}
public static void main( String args [] ) {
MyAWTMenu objAppFrame = new MyAWTMenu();
objAppFrame.addWindowListener( //Register an anonymous class as a listener.
new WindowAdapter() {
public void windowClosing( WindowEvent e )
{
System.exit( 0 );
}
}
);
objAppFrame.init();
objAppFrame.setSize( 760, 378);
objAppFrame.setVisible( true );
}

I'd better rewrite it as follows:
public class FooFrame extends JFrame {
public FooFrame() {
// your code, copy/pasted
setBackground(Color.white);
JPanel bottom = new JPanel();
bottom.setBackground(Color.BLACK);
JButton b1 = new JButton("test");
bottom.add(b1);
add(bottom, BorderLayout.CENTER);
// set size & pack
Dimension size = new Dimension(400, 400);
setPreferredSize(size);
setMinimumSize(size);
pack();
setLocationRelativeTo(null);
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new FooFrame().setVisible(true);
}
});
}
}

add(bottom,BorderLayout.SOUTH);
in your init()
Here's your code that i was running. It seems to work fine for me. I did add a call to pack();
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JPanel;
public class MyAWTMenu extends java.awt.Frame// implements ActionListener
{
public void init() {
setBackground(Color.white);
JPanel bottom = new JPanel();
bottom.setBackground(Color.BLACK);
JButton b1 = new JButton("test");
bottom.add(b1);
bottom.setVisible(true);
add(bottom, BorderLayout.SOUTH);
pack();
}
public static void main(String args[]) {
MyAWTMenu objAppFrame = new MyAWTMenu();
objAppFrame.addWindowListener( //Register an anonymous class as a listener.
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
objAppFrame.init();
objAppFrame.setSize(760, 378);
objAppFrame.setVisible(true);
}
}