I'm just starting out with Swing - I'm sorry if this question is hard to follow, but I feel like this is a very simple thing but it seems surprisingly hard in Swing.
I have a panel with two text fields and a submit button.
I've added a listener on the submit button, when it's clicked I validate the data and such.
Now, I want the frame to display a new panel - get rid of the current panel with the text fields and submit button, and instantiate a new one based on the data entered in the text fields.
How can I send this data back to the frame, so the frame can remove the current panel and replace it with a new, different panel, created with the data from the first panel.
Though it's not what I'm doing, it could be thought of like a login.
Display login panel
Panel gets username and password, validates (validation could be done higher up, too)
If validated, replace login panel with real content panel
This is surprisingly hard to figure out in Swing. Should I be defining my own event type and making the frame a listener for that event?
If I understood your question, you can use callback logic like this;
MyLoginPanel login = new MyLoginPanel(new IMyCallback(){
public void processLogin(){
//frame can remove the current panel and replace it with a new
}
});
MyLoginPanel extended from Jpanel with Constructor public MyLoginPanel(IMyCallback callback)
IMyCallback is an interface which has public void processLogin() method.
You could call callback.processLogin(); from LoginPanel
Does it work for you?
You should look at the java.awt.CardLayout. This Layout can handle multiple panels which are stacked on top of each other. And you can choose which panel should be the topmost and therefore visible.
The following code shows the relevent parts from the tutorial mentioned above:
//Where instance variables are declared:
final static String BUTTONPANEL = "Card with JButtons";
final static String TEXTPANEL = "Card with JTextField";
//Where the components controlled by the CardLayout are initialized:
//Create the "cards".
JPanel card1 = new JPanel();
JPanel card2 = new JPanel();
//Create the panel that contains the "cards".
JPanel cards = new JPanel(new CardLayout());
cards.add(card1, BUTTONPANEL);
cards.add(card2, TEXTPANEL);
and to switch the visible panel:
CardLayout cl = (CardLayout)(cards.getLayout());
cl.show(cards, TEXTPANEL);
Related
I have some experience in Java creating Apps and would like to learn more, and so have decided to create an application that will have different pages. For example the initial frame will show a menu of buttons that will lead to different frames, showing different components and layouts.
I'm not too sure the best practice of implementing pages. I think I could store the JFrame windows in a list, then use a button handler class to maybe change the visibility of the different frames, only allowing the relevant frame to be visible when the user clicks on a button. I think this method could work, but is there a more efficient/practical way of doing this?
I am aware of CardLayout, however for this program I am trying to learn MigLayout; so that won't be possible (as far as I'm aware). I hope this question is not too vague, I'd just like to know the best practice when it comes to creating applications in Java with different pages.
Can use Tabbed Panes, it is the best for storing pages.
https://docs.oracle.com/javase/tutorial/uiswing/components/tabbedpane.html
Also I noticed that you need to consider top level containers properly, because you don't need to create every time a JFrame for each Page, at least if it was necessary(For example: an editor, create a new window so you need to create a new JFrame, in your case I don't think so) so please consider the link below.
https://docs.oracle.com/javase/tutorial/uiswing/components/toplevel.html
JInternalFrame is a part of Java Swing . JInternalFrame is a container that provides many features of a frame which includes displaying title, opening, closing, resizing, support for menu bar, etc. Internal frames with components example
Code to create multiple internal frames:
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
class solution extends JFrame {
// frame
static JFrame f;
// label to diaplay text
static JLabel l, l1;
// main class
public static void main(String[] args) {
// create a new frame
f = new JFrame("frame");
// set layout of frame
f.setLayout(new FlowLayout());
// create a internal frame
JInternalFrame in = new JInternalFrame("frame 1", true, true, true, true);
// create a internal frame
JInternalFrame in1 = new JInternalFrame("frame 2", true, true, true, true);
// create a Button
JButton b = new JButton("button");
JButton b1 = new JButton("button1");
// create a label to display text
l = new JLabel("This is a JInternal Frame no 1 ");
l1 = new JLabel("This is a JInternal Frame no 2 ");
// create a panel
JPanel p = new JPanel();
JPanel p1 = new JPanel();
// add label and button to panel
p.add(l);
p.add(b);
p1.add(l1);
p1.add(b1);
// set visibility internal frame
in.setVisible(true);
in1.setVisible(true);
// add panel to internal frame
in.add(p);
in1.add(p1);
// add internal frame to frame
f.add(in);
f.add(in1);
// set the size of frame
f.setSize(300, 300);
f.show();
}
}
Ok I'm using Card Layout to switch panels from 1 panel to a 2nd panel & then to a 3rd panel. I have been looking online but I can't find exactly what I'm looking for. I want my panels to be in different classes and to switch back and forth using buttons to the different panels. I found a couple of sources for this but all the panels are added to a an original panel and then it switch's to different panels using the same buttons from the original panel.
(i.e) Panel 2 uses buttons from Panel 1 to switch to Panel 3 and Panel 3 uses buttons from Panel 1 to switch to Panel 4 and Panel 4 uses buttons from Panel 1 to switch back to Panel 2.
But the way it should be is panel 1 uses buttons from panel 1 to switch to panel 2, panel 2 uses buttons from panel 2 to switch to panel 3 and panel 3 should use buttons from panel 3 to switch to panel 1 which means there should be no need for a 4th panel.
My issue is I want to use different buttons to switch back and forth and not the same buttons as I intend to write extra code in each button for each panel. Because I basically want to create 3 panels so that once details are added to the register form and the user clicks register the details are added to the database and then it switch's to a login panel and closes the register panel.
The login panel then takes in a username and a password if they match an entry in the database and the user clicks login go to new panel and close login panel.
Now I have the registering and login stages done it's just switching from 1 panel to the next is the issue. Is there a way to use card layout so you switch to different panels using different buttons for each panel to do this or is there some other method used to do this.
I can append my code if needed. but its connected to a database so it won't compile without the database.
You definitly need a 4. panel witch contains the 3 panels and has the cardLayout.
To change the cards from cards you need to hand over an actionlistener with the method next(). I made a small not visual nice example to show what I mean ;-)
public class CardExample{
private class panel extends JPanel{
private panel(ActionListener alNext, String text){
JButton buttonNext = new JButton("next");
buttonNext.addActionListener(alNext);
JLabel textLabel = new JLabel(text);
this.add(textLabel);
this.add(buttonNext);
}
}
public CardExample(){}
public static void main(String[] args){
CardExample ce = new Cardexample();
ce.myGUI();
}
private void myGUI() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setSize(200, 200);
CardLayout cardLayout = new CardLayout();
frame.getContentPane().setLayout(cardLayout);
ActionListener al = e -> cardLayout.next(frame.getContentPane());
frame.getContentPane().add(new panel(al, "Panel 1"));
frame.getContentPane().add(new panel(al, "Panel 2"));
frame.getContentPane().add(new panel(al, "Panel 3"));
frame.setVisible(true);
}
}
Whether the buttons are on the same panel or a different panel is irrelevant.
The button just executes a method from the layout manager. You can use:
next(...) - to go the next panel in the CardLayout, or
show(...) - to show a specific panel in the CardLayout.
If you don't have access to the panel using the CardLayout you can easily get this. In the ActionListener for your button you can do something like:
JButton button = (JButton)event.getSource();
JPanel buttonPanel = (JPanel)button.getParent();
JPanel cardPanel = (JPanel)buttonPanel.getParent();
CardLayout layout = (CardLayout)cardPanel.getLayout();
layout.next(cardPanel);
public class Create_JFrame extends JFrame{
public Create_JFrame(){
//Create a Frame
JFrame Frame = new JFrame("Bla-Bla");
JPanel Panel_1 = new JPanel();
JPanel Panel_2 = new JPanel();
JButton Option_1 = new JButton("Option-1");
//Layout management for Panels
Frame.getContentPane().add(BorderLayout.WEST, Panel_1);
//Add button to Panel
Panel_1.add(Option_1);
//Registering Listeners for all my buttons
Option_1.addActionListener(new ListenerForRadioButton(Panel_2));
//Make the frame visible
Frame.setSize(500, 300);
Frame.setVisible(true);
}//end of Main
}//end of Class
public class ListenerForRadioButton implements ActionListener{
JPanel Panel_2;
JButton browse = new JButton("Browse");
//Constructor, will be used to get parameters from Parent methods
public ListenerForRadioButton(JPanel Panel){
Panel_2 = Panel;
}
//Overridden function, will be used for calling my 'core code' when user clicks on button.
public void actionPerformed(ActionEvent event){
Panel_2.add(browse);
System.out.println("My listener is called");
}//end of method
}//end of class
Problem Statement:
I have 2 JPanel components in a a given JFrame. Panel_1 is having a Option_1 JButton. When user clicks on that I am expecting my code to add a JButton 'browse' in Panel_2 at runtime.
Runtime Output:
System is not adding any JButton in Panel_2. However, I see my debug message in output, indicating that system was successful in identifying user's click action on 'option-1'.
Question:
Why is JPanel not adding any component at Runtime?
Panel_2.add(browse);
Panel_2.revalidate();
adding a 'revalidate' will solve the problem.
There are some reasons. but:
usually it's because of using unsuitable LayoutManager.
sometimes it's because of adding the JPanel to it's root component in worng way. which any operation (add, remove,...) works but is not visible.
you must refresh the view when you make some changes on it, like adding or removing components to/from it.
try to use Panel_2.revalidate() to refresh.
if it doesn't work properly use it with Panel_2.repaint() method.
see Java Swing revalidate() vs repaint()
see Difference between validate(), revalidate() and invalidate() in Swing GUI
using setSize twice for your jframe is another way.
Frame.setSize(498, 300); then Frame.setSize(500, 300);
So I'm writing a program in which I wish to have a single JFrame containing a JPanel header in a separate colour and directly underneath have a grid of buttons in a separate JPanel. So far my program works perfectly except for the fact that the header String isn't showing up in the NORTH panel. Instead I'm getting a box containing the set background colour with a small grey box in the centre. I'm wondering if I didn't set the size of the panel correctly?
I have heard this can be accomplished using JLabel, but when I tried to do this, it would not show the background colour that I had set.
So, could anyone please show me how to achieve the following either with the JPanel (preferably because I would like to know how it works and what I'm missing) or with JLabel: filling that little grey box in the middle of the header with a String.
Here is my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Example {
public static void main(String[] args) {
// Initialize a panel for the header, and mainGrid which will contain buttons
JPanel panel = new JPanel();
JPanel header = new JPanel();
JPanel mainGrid = new JPanel();
// Initialize the header
DisplayPanel message = new DisplayPanel();
header.setBackground(Color.ORANGE);
header.add(message);
// Initialize the mainGrid panel
mainGrid.setLayout(new GridLayout(2,2,2,2));
mainGrid.add(new JButton("1"));
mainGrid.add(new JButton("2"));
mainGrid.add(new JButton("3"));
mainGrid.add(new JButton("4"));
// Add the two subpanels to the main panel
panel.setLayout(new BorderLayout());
panel.add(header, BorderLayout.NORTH); // The issue is this panel isn't displaying the String created in DisplayPanel
panel.add(mainGrid, BorderLayout.CENTER);
// Add main panel to JFrame
JFrame display = new JFrame("Test");
display.setContentPane(panel);
display.setSize(200,100);
display.setLocation(500,200);
display.setVisible(true);
display.setResizable(false);
display.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private static class DisplayPanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("header" , 20, 20); // The string I want to be displayed
}
}
}
I would very much appreciate anyone's help or input as I have only been studying Java for a few months and this is my first post. Thank you in advance.
Also, any general tips on writing that you may have would be greatly appreciated.
I'm wondering if your problem is that you're nesting your message JPanel inside of the header JPanel, and the container header JPanel uses the JPanel default FlowLayout. Thus the component it holds won't expand on its own and will remain trivially small.
Consider either giving the header JPanel a BorderLayout so that message expands inside of it, or
use a JLabel to show your text, not a JPanel's paintComponent method. The JLabel should size itself to be big enough to show its text. If you do this and want it to show a background color, all you have to do is call setOpaque(true) on your JLabel, and you're set.
Actually, if you nest the JLabel, then there's no need to make it opaque. Just do this:
JPanel header = new JPanel();
JPanel mainGrid = new JPanel();
JLabel message = new JLabel("Header", SwingConstants.CENTER);
header.setBackground(Color.ORANGE);
header.setLayout(new BorderLayout());
header.add(message);
I would highly recommend using a GUI builder WYSIWYG IDE, like NetBeans, where you can easily drag and drop components to where they need to be. If you're doing any sort of complex GUI layout, it can be madness (and in my opinion, nonsensical) trying to write and maintain the code.
The layout your trying to implement would be trivial in NetBeans.
I'm writing a simple java game and I'm facing this problem:
My different layouts are in different JPanels (1 JPanel for the welcoming page, where I have to press 'start game' and another one with the actuall functionallity)
I start the game from a JFrame
import javax.swing.JFrame;
public class RType extends JFrame {
public RType() {
add(new Welcome());//first panel
add(new Board());//panel with the game
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(100, 100);
setResizable(false);
setVisible(true);
}
public static void main(String[] args) {
new RType();
}
}
obviuosly, this launches the second panel right after the first, and I cant see the first one.
I've tried some stuff, trying to invoke the second panel in the main method, when the first panel is clicked that way:
RType rt=new RType();
rt.add(new Board()); //in this case add(new Board()); is removed from constructor
but it's doing nothing.
how can I solve it?
As #nachokk has said, you should be using a CardLayout instead. It lets you do things like tabs in a browser, but you don't need to make the tabs visible for your game if you don't want to. You make your welcome "card" visible at first, then when the user clicks you switch to the Board "card".
I don't recommend to add directly to the JFrame components, instead use another container as JPanel . JFrame default layout is BorderLayout, when you add in the way you are adding it always put in the center.
Make something like this:
JFrame frame = new JFrame();
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new CardLayout());
mainPanel.add(new Welcome(), "Welcome");
mainPanel.add(new Board(),"Board");
frame.add(mainPanel);
Here is a tutorial How to use CardLayout
on first panel of welcome add a button, and apply actionperformed like
JButton myButton = new JButton("Add Component ");
myButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frame.remove(welcome);
frame.add(Board, BorderLayout.CENTER);
frame.revalidate();
frame.repaint();
}
});
By default, both panels will fill up the entire Frame's area. To fix this, you will need to use another layout, such as a GridLayout to structure the areas in which the panels will take up the Frame's area.
You can also go with no layout to hard code the pixel values of where you want the panels to fit in your frame.
EDIT: Based on what you're looking to do, the CardLayout is probably what you'll want to use for your Frame's layout.