I am trying to add multiple panels to another panel. I want them to be on top of each other so I'm using JLayeredPane. I've added a button to each one. Two buttons should appear when it works.
import java.awt.Color;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
public class PanelTest {
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel mainPanel = new JPanel();
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
JLayeredPane layers = new JLayeredPane();
mainPanel.add(layers);
panel2.setOpaque(false);
panel1.setOpaque(false);
panel1.setVisible(true);
panel2.setVisible(true);
panel1.add(new JButton("1111111111"));
panel2.add(new JButton("2"));
frame.setContentPane(mainPanel);
layers.add(panel1, new Integer(2));
layers.add(panel2, new Integer(3));
frame.setVisible(true);
frame.setSize(500, 500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Only the grey background of the mainPanel is visible. What am I doing wrong?
When adding a component to a JLayeredPane, you're essentially adding the component to a null layout using container. This means that you must fully specify both the component's size and its position, often solving both with a setBounds(...) call. Call this on panel1 and panel2, for example:
panel1.setBounds(10, 10, 100, 100);
panel2.setBounds(70, 70, 100, 100);
Edit:
setting bounds didn't make any difference
Setting the size (bounds) is required but you still have an additional problem.
You are adding the JLayeredPane to a JPanel which uses a FlowLayout. By default a FlowLayout respects the preferred size of the component added to it. Since JLayeredPane uses a null layout its preferred size is (0, 0) so there is nothing to paint.
Two solutions:
You don't need the JPanel, just use: frame.setContentPane(layers);
If you really want to use the panel then you need to change the layout manager: JPanel mainPanel = new JPanel( new BorderLayout());
Related
I'm working on a Swing GUI using the JLayeredPane. The JFrame has a JLayeredPane which contains two JPanels. Later I want to display some components in the JPanels, I cut this part of the code to make it shorter for you.
How do I resize the JFrame to the sizes of the JPanels? frame.pack() does not work and without the line setting the preferred size the GUI will show with minimal size.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
public class TestGUI {
private JFrame frame;
private JLayeredPane layeredPane;
private JPanel panelBottom;
private JPanel panelTop;
private MainMenuBar menuBar;
public TestGUI() {
// panel bottom:
panelBottom = new JPanel();
panelBottom.setSize(1000, 500);
panelBottom.setBackground(new Color(0, 100, 0, 100));
panelBottom.setLayout(new GridBagLayout());
// panel top:
panelTop = new JPanel();
panelTop.setSize(950, 450);
panelTop.setBackground(new Color(0, 0, 100, 100));
panelTop.setLayout(new GridBagLayout());
// layered pane:
layeredPane = new JLayeredPane();
layeredPane.add(panelBottom, 1);
layeredPane.add(panelTop, 0);
// frame building:
frame = new JFrame();
menuBar = new MainMenuBar();
frame.setJMenuBar(menuBar);
frame.setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(1100, 600)); // <-- Without this the GUI will be very small
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(layeredPane, BorderLayout.CENTER);
frame.pack(); // <-- does not work!
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
new TestGUI();
}
}
EDIT: I could just change the preferred size line to fit the biggest JPanel, but i ask the question because I want the JFrame to resize depending on the size of the JPanels dynamically.
As suggested in How to Use Layered Panes: Laying Out Components in a Layered Pane, "Although a layered pane has no layout manager by default, you can still assign a layout manager to the layered pane." Use OverlayLayout, seen here, for overlapping panels.
Alternatively, use JInternalFrame, which does allow you to pack() the internal frames individually, as shown here and here.
how can i modify the size of the panel in the JFrame
am doing a calculator, the first panel will hold the JTextField which i suppose to be small
the second panel will hold the JButtons which suppose to be bigger
JFrame frame = new JFrame(new GridLayout(2, 1));
JPanel panel1 = new JPanel();
JPanel panel2 = new JPabel();
frame.add(panel1);
frame.add(panel2);
i've been trying to make panel1 smaller than panel2 yet nothing worked!
GridLayout would not be an appropriate choice in this scenario since it ignores the preferred sizes of the components inside the container and displays them all at an equal size instead.
I'd suggest using a BorderLayout. You can find a demonstration and description of that layout manager as well as a few others in Oracle's tutorial, A Visual Guide to Layout Managers.
Here's another example using BorderLayout which might be more relevant to your problem.
import java.awt.*;
import javax.swing.*;
public class Test {
public static void main(String []args){
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame();
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
panel1.setBorder(BorderFactory.createTitledBorder("Panel 1"));
panel2.setBorder(BorderFactory.createTitledBorder("Panel 2"));
frame.add(panel1, BorderLayout.NORTH);
frame.add(panel2, BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(new Dimension(200, 200));
frame.setVisible(true);
}
});
}
}
Edit: The JFrame's content pane uses a BorderLayout by default, hence the absence of a call to setLayout. Source
Experimenting with layered panes here and I'm having a problem. I have two JPanels. I'm adding them both to a JLayeredPane - panel1 is big enough to take up the whole space, while panel2 is smaller and centered using FlowLayout. The problem is that with JLayeredPane, the background next to panel2 seems to be painted white when I add it. Here's a picture to illustrate. panel1 is blue, panel2 is red:
As you can see, the bottom part of the panel1 is still painted, but for some reason the sides are just white. The panel2 is 700 pixels wide and centered, while the frame is 800 pixels wide, so it's definitely not a problem with that. Here's the entire class:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
public class Errortest extends JFrame {
public static void main(String[] args) {
//Creating frame and setting the JLayeredPane as contentpane
Errortest frame = new Errortest();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLayeredPane pane = new JLayeredPane();
pane.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
pane.setPreferredSize(new Dimension(800,600));
frame.setContentPane(pane);
frame.pack();
//Creating panels
JPanel panel1 = new JPanel();
panel1.setPreferredSize(new Dimension(800,600));
panel1.setBackground(Color.BLUE);
JPanel panel2 = new JPanel();
panel2.setPreferredSize(new Dimension(700,500));
panel2.setBackground(Color.RED);
pane.add(panel1, new Integer(0));
pane.add(panel2, new Integer(1));
frame.setVisible(true);
}
}
Hopefully that wasn't too confusing. From what I can tell, the white background comes from the JFrame itself, since when I do frame.setBackground(Color.YELLOW); it turns yellow.
If you add a component to a JLayeredPane, it's like adding it to a null layout using container: you must fully specify the component's size and position.
import java.awt.*;
import javax.swing.*;
public class ErrorTest extends JFrame {
public static void main(String[] args) {
// Creating frame and setting the JLayeredPane as contentpane
ErrorTest frame = new ErrorTest();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent pane = new JLayeredPane();
//pane.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0)); // Take out FlowLayout
pane.setPreferredSize(new Dimension(800, 600));
frame.setContentPane(pane);
// Creating panels
JPanel panel1 = new JPanel();
panel1.setBackground(Color.BLUE);
panel1.setBounds(0, 0, 800, 600); // <<<---- Set Bounds
JPanel panel2 = new JPanel();
panel2.setBackground(Color.RED);
panel2.setBounds(50, 0, 700, 500); // <<---- Set Bounds
pane.add(panel1, new Integer(1));
pane.add(panel2, new Integer(2));
frame.pack();
frame.setVisible(true);
}
}
I believe I found out what the problem is. Has to do with the answer here:
JLayeredPane not respecting layers
You need a layout manager which understands the Z-Axis. The default layout managers don't understand the Z-Axis of the JLayeredPane.
So it's the FlowLayout that's messing me up. I'll just use absolute positioning for my project and use setBounds() to make sure the red panel ends up in the middle. Otherwise I'd have to look into custom layout managers I suppose.
Here is my code to add to component (JTextArea and JList) to a panel and put it on the frame. Can I divide half/half by BorderLayout?
If yes why mine looks messy one stays up one down?
What is the other alternative?
Regards,
Bernard
import java.awt.*;
import javax.swing.BorderFactory;
import javax.swing.border.Border;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JTextArea;
public class SimpleBorder {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(500,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Border etched = (Border) BorderFactory.createEtchedBorder();
String[] items = {"A", "B", "C", "D"};
JList list = new JList(items);
JTextArea text = new JTextArea(10, 40);
JScrollPane scrol = new JScrollPane(text);
JScrollPane scrol2 = new JScrollPane(list);
JPanel panel= new JPanel();
panel.add(scrol2,BorderLayout.WEST);
panel.add(scrol, BorderLayout.EAST);
panel.setBorder(etched);
frame.add(panel);
frame.setVisible(true);
}
}
The default Layout manager for JPanel is FlowLayout, so adding components without actually setting the layout to an instance of BorderLayout will produce unexpected results.
To get a half/half layout you could use GridLayout:
JPanel panel= new JPanel(new GridLayout(1, 2));
You must use a different LayoutManager, BorderLayout will not allow you add components that use only 50% of the visible space. I personally use GridBagLayout, which allows you to specify many parameters (free space distribution, new lines of components, alignment, etc.).
You should set the LayoutManager of your JPanel to BorderLayout first (only ContentPanes i.e frame#getContentPane() have a default layout of BorderLayout):
JPanel panel= new JPanel(new BorderLayout());
panel.add(scrol2,BorderLayout.WEST);
panel.add(scrol, BorderLayout.EAST);
panel.setBorder(etched);
As described in the title. I've got two JPanels one on top of the other using a BorderLayout().
import java.awt.*;
import javax.swing.*;
public class myForm(){
public static void main(String[] args) {
JFrame myFrame = new JFrame("SingSong");
myFrame.setLocation(100,100);
myFrame.setSize(new Dimension(1024,800));
myFrame.setLayout(new BorderLayout());
JPanel jp = new JPanel();
jp.setBackground(new Color(0x00FF00FF));
JPanel jp2 = new JPanel(new BorderLayout());
jp2.setBackground(new Color(0x00000000));
jp.setPreferredSize(new Dimension(100,400));
jp2.setPreferredSize(new Dimension(100,400));
jp2.setLocation(0, 512);
myFrame.add(jp2, BorderLayout.SOUTH);
myFrame.add(jp, BorderLayout.NORTH);
}
}
They each take up half, but how can I go about setting it so that they always take up half the JFrame each, even when resized?
(P.S. I normally use better variable names, I just whipped up that as an SSCCE)
Try the GridLayout
JFrame myFrame = new JFrame("SingSong");
myFrame.setLocation(100, 100);
myFrame.setSize(new Dimension(1024, 800));
GridLayout layout = new GridLayout(2, 1);
myFrame.setLayout(layout);
JPanel jp = new JPanel();
jp.setBackground(new Color(0x00FF00FF));
JPanel jp2 = new JPanel(new BorderLayout());
jp2.setBackground(new Color(0x00000000));
myFrame.add(jp);
myFrame.add(jp2);
myFrame.setVisible(true);
when you setPreferredSize, the layout manager will make it so that both the panels are always 400 pixels tall. If you want the panels to always be half of the height of the frame, then don't set the preferred size. If that doesn't work, then you could always try setting the panels' height to (myFrame.getSize().height) / 2 which will be half the height of the frame.