Is it possible to use the size of a JPanel to set the size of components inside the JPanel? When I try to use getHeight() or getWidth() on the JPanel it always returns 0. I know that it gets it's size once the JFrame is packed, but how would one go about using the dimensions of the JPanel and applying it to a component inside it? Something like this
JPanel panel = new JPanel();
JLabel label = new JLabel();
label.setWidth(panel.getWidth());
panel.add(label);
EDIT:
See sample code below. What should I do if I want my Jlabel to be as wide as my JPanel? Is it wrong to use boxlayout in this case?
public class Main extends JFrame{
public Main(){
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.setBorder(BorderFactory.createLineBorder(Color.blue));
JLabel label = new JLabel();
label.setBorder(BorderFactory.createLineBorder(Color.red));
label.setText("label1");
label.setMinimumSize(panel.getPreferredSize());
label.setPreferredSize(panel.getPreferredSize());
panel.add(label);
add(panel);
setDefaultCloseOperation(EXIT_ON_CLOSE);
pack();
setSize(500,500);
setVisible(true);
}
public static void main(String[] args)
{
new Main();
}
}
Is it possible to use the size of a JPanel to set the size of components inside the JPanel?
This is the job of the layout manager.
When I try to use getHeight() or getWidth() on the JPanel it always returns 0
When the layout manager is invoked the Container will have a valid size so the layout manager can do its job properly.
There is no reason for you to be playing with sizes. Leave it to the layout managers to do their jobs.
Update:
What should I do if I want my Jlabel to be as wide as my JPanel? Is it wrong to use boxlayout in this case?
The BoxLayout attempts to respect the minimum/maximum size of the component. In you case you should be able to do something like:
JLabel label new JLabel("some text");
label.setBorder(....);
Dimension d = label.getPreferredSize();
d.width = 32767;
label.setMaximumSize( d );
Or maybe a simpler approach is to start with a BorderLayout. You can add the label to the NORTH. Then create another panel and add it to the CENTER.
Of course you can, but be careful that the result depends on the layout manager of your JPanel and on the number of its child components.
Setting the width ignores resizing. LayoutManagers typically ask components for their preferred widths and heights, and expand / contract items to maintain a visually appealing position after the frame has been resized. So, your best option is to leverage the layout manager and report a "preferred width".
You can use setPreferredWidth(...); but, if your preferred width is to change over the run of the program (due to window size changes), you will need to listen to the panel in question and update your button's preferred width as the panel's preferred width changes (this assumes it changes, which might not be true).
Related
I have a JPanel. Inside Panel I have kept one JLabel and three JCheckBox.
I want to keep all the checkBox in one line after JLabel. Here is the sample code and some screenshots.
Output 1
Output 2
When i change to X_AXIS it is coming everything in one line and when i switch to Y_AXIS then it is coming new line means vertically.
But my requirement is all the checkbox should come next line means after JLabel.
JLabel should come in line and all the checkBox should come in one line.
public class CheckBoxWithJLabel {
public static void main(String[] args) {
JFrame f= new JFrame("CheckBox Example");
JPanel panel = new JPanel();
panel.setBounds(40,80,600,200);
JCheckBox chk_Embrodary=new JCheckBox("Embrodary");
JCheckBox chk_Cutting=new JCheckBox("Cutting");
JCheckBox cb_Sewing=new JCheckBox("Sewing");
panel.setLayout(new javax.swing.BoxLayout(panel, javax.swing.BoxLayout.X_AXIS));
JLabel lblHeader=new JLabel("Job Work Process Selection");
panel.add(lblHeader);
panel.add(chk_Embrodary);
panel.add(chk_Cutting);
panel.add(cb_Sewing);
f.add(panel);
f.setSize(600,400);
f.setLayout(null);
f.setVisible(true);
}
}
I want this output like
this
How to solve this problem?
I would highly suggest you to have a look through the Java Swing Tutorial, especially the Laying Out Components Within a Container section, since it seems you lack some basic understanding of how Swing and its Layout Managers are supposed to be used.
Regarding your problem:
Currently, you are using a single BoxLayout, which " puts components in a single row or column". You only want that behavior for your JCheckBoxes though, and not for your JLabel. Keeping this in mind, the solution is to split up your components and to not put all of them in a single JPanel. Doing this will grant you more flexibility in how you design your GUI, since you can use multiple layouts in different nested panels.
You could do something like this (explanation in the code comments):
public static void main(String[] args) {
JFrame f = new JFrame("CheckBox Example");
// add a Y_AXIS boxlayout to the JFrames contentpane
f.getContentPane().setLayout(new BoxLayout(f.getContentPane(), BoxLayout.Y_AXIS));
JCheckBox cbEmbrodary = new JCheckBox("Embrodary");
JCheckBox cbCutting = new JCheckBox("Cutting");
JCheckBox cbSewing = new JCheckBox("Sewing");
// no need to set the bounds, since the layoutmanagers will determine the size
JPanel labelPanel = new JPanel(); // default layout for JPanel is the FlowLayout
JLabel lblHeader = new JLabel("Job Work Process Selection");
labelPanel.add(lblHeader); // JPanel for the label done
// JPanel for the comboboxes with BoxLayout
JPanel cbPanel = new JPanel();
cbPanel.setLayout(new BoxLayout(cbPanel, BoxLayout.X_AXIS));
cbPanel.add(cbEmbrodary);
cbPanel.add(cbCutting);
cbPanel.add(cbSewing);
f.add(labelPanel);
f.add(cbPanel);
// No need to set the size of the JFrame, since the layoutmanagers will
// determine the size after pack()
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
Output:
Sidenotes:
Don't set fixed sizes via setSize() or setBounds() to your components. Swing is designed to be used with appropariate LayoutManagers, and if you do that, calling pack() on the JFrame before setting it visible will layout the components and determine their appropriate size. (Also, don't use null-layout for the same reasons)
If you need the JLabel to not be centered but left aligned, like in your screenshot, then use the following:
FlowLayout layout = (FlowLayout) labelPanel.getLayout();
layout.setAlignment(FlowLayout.LEFT);
I have a JPanel subclass on which I add buttons, labels, tables, etc. To show on screen it I use JFrame:
MainPanel mainPanel = new MainPanel(); //JPanel subclass
JFrame mainFrame = new JFrame();
mainFrame.setTitle("main window title");
mainFrame.getContentPane().add(mainPanel);
mainFrame.setLocation(100, 100);
mainFrame.pack();
mainFrame.setVisible(true);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
But when I size the window, size of panel don't change. How to make size of panel to be the same as the size of window even if it was resized?
You can set a layout manager like BorderLayout and then define more specifically, where your panel should go:
MainPanel mainPanel = new MainPanel();
JFrame mainFrame = new JFrame();
mainFrame.setLayout(new BorderLayout());
mainFrame.add(mainPanel, BorderLayout.CENTER);
mainFrame.pack();
mainFrame.setVisible(true);
This puts the panel into the center area of the frame and lets it grow automatically when resizing the frame.
You need to set a layout manager for the JFrame to use - This deals with how components are positioned. A useful one is the BorderLayout manager.
Simply adding the following line of code should fix your problems:
mainFrame.setLayout(new BorderLayout());
(Do this before adding components to the JFrame)
If the BorderLayout option provided by our friends doesnot work, try adding ComponentListerner to the JFrame and implement the componentResized(event) method. When the JFrame object will be resized, this method will be called. So if you write the the code to set the size of the JPanel in this method, you will achieve the intended result.
Ya, I know this 'solution' is not good but use it as a safety net.
;)
From my experience, I used GridLayout.
thePanel.setLayout(new GridLayout(a,b,c,d));
a = row number, b = column number, c = horizontal gap, d = vertical gap.
For example, if I want to create panel with:
unlimited row (set a = 0)
1 column (set b = 1)
vertical gap= 3 (set d = 3)
The code is below:
thePanel.setLayout(new GridLayout(0,1,0,3));
This method is useful when you want to add JScrollPane to your JPanel. Size of the JPanel inside JScrollPane will automatically changes when you add some components on it, so the JScrollPane will automatically reset the scroll bar.
As other posters have said, you need to change the LayoutManager being used. I always preferred using a GridLayout so your code would become:
MainPanel mainPanel = new MainPanel();
JFrame mainFrame = new JFrame();
mainFrame.setLayout(new GridLayout());
mainFrame.pack();
mainFrame.setVisible(true);
GridLayout seems more conceptually correct to me when you want your panel to take up the entire screen.
I'm programming right now a Chomp Game for Uni. Everything works fine but the Label at the bottom. Its background is supposed to fill out the entire bottom. In the attachment you can see how it instead looks now. I tried setting the minimum and the preferred size of the label. The Height is changing but the width just stays adjusted to the text. How can I change that?
Note: The snippet only contains the setting up of the Frame and Panels in a custom method and not the main class.
private void init()
{
JFrame fenster = new JFrame();
this.spielfeld = new SpielfeldPanel(M, N);
this.anzeige = new SpielerAnzeigeLabel(this.spieler);
JPanel panel = new JPanel();
BoxLayout boxlayout = new BoxLayout(panel,BoxLayout.Y_AXIS);
panel.setLayout(boxlayout);
fenster.setTitle("Chomp");
fenster.setSize(1000,700);
panel.setPreferredSize(new Dimension(1000, 60));
Dimension d = new Dimension(getPreferredSize());
panel.setMinimumSize(d);
panel.add(spielfeld);
panel.add(anzeige);
fenster.add(panel);
this.spielfeld.setVisible(true);
this.anzeige.setVisible(true);
panel.setVisible(true);
fenster.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
A BoxLayout respects the width of the component to the label is displayed at its preferred width/height.
A JFrame uses a BorderLayout by default. So just add the label to the frame independently of the panel:
//panel.add(anzeige);
//fenster.add(panel);
fenster.add(panel, BorderLayout.CENTER);
fenster.add(anzeige, BorderLayout.PAGE_END);
The PAGE_END constraint respects the height but makes the width equal to the space available. Read the section from the Swing tutorial on How to Use BorderLayout for more information and examples.
I am a newbie, I have a question. I am trying to use Eclipse to write a Java windows application, in which I will have a main window, which will contain several things, like a dashboard sort of thing, and it will have buttons, for example to add a record to a database, and this button when pressed, will open a new relevant window on top.
I tried to start, I wrote this code in Java, and for some reason, the button is in the size of the frame...full screen ! How do I fix it ?
Can you suggest me better ideas for a design than what I specified ?
Thank you
public class MainClass {
public static void main(String[] args) {
// TODO Auto-generated method stub
JFrame jfrm = new JFrame("Frame1");
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
jfrm.setSize(screenSize.width, screenSize.height);
jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel jlab = new JLabel("Hello");
jfrm.add(jlab);
JButton button = new JButton("Button");
button.setSize(new Dimension(50, 50));
button.setLocation(500, 350);
jfrm.getContentPane().add(button);
jfrm.setVisible(true);
}
Add a layout to the JFrame first. For example FlowLayout:
jfrm.setLayout(new FlowLayout());
"I tried to start, I wrote this code in Java, and for some reason, the button is in the size of the frame...full screen ! How do I fix it ?"
The reason the button stretches is because JFrame has a default BorderLayout that does not respect the preferred sizes of child components.
The solution is to set the Layout Manager to layout that does respect preferred sizes. The image blow from this example shows the most common Layout Managers and show visually which one respect the preferred size of child components.
Also, the BorderLayout is also the reason your JLabel does not show. By default, every component that is added to a BorderLayout without a position specified e.g. BorderLayout.SOUTH, will automatically be placed in the BorderLayout.CENTER position. Each position may only have one component. So when you add the JLabel it goes to the CENTER, but when you add the JButton, it also goes the CENTER, kicking out the JLabel.
If you've never encountered Layout Managers, this is probably all confusing to you. You should take the time to go over How to Layout Components Within a Container
You need to use some form of layoutmanager, you can use this information: http://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
You must use Layout manager.
Use this code..
public static void main(String[] args)
{
JFrame jfrm = new JFrame("Frame1");
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
jfrm.setSize(screenSize.width, screenSize.height);
jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel jlab = new JLabel("Hello");
jfrm.add(jlab);
JButton button = new JButton("Button");
button.setSize(new Dimension(50, 50));
button.setLocation(500, 350);
jfrm.add(button);
jfrm.setVisible(true);
jfrm.setLayout(new FlowLayout());
jfrm.pack();
you forgot to add pack(). so use this code to get Jlabel and JButtion side by side.
Thanks...
I have 3 panels. One is the main panel which holds 2 smaller panels.
For the main panel, I used
setPreferredSize(new Dimension(350, 190));
For the smaller left panel, I used
setPreferredSize(new Dimension(100, 190));
For the smaller right panel, I used
setPreferredSize(new Dimension(250, 190));
but the smaller panels remain the same size. How can I fix this?
This is the code I have in my main Panel.
import model.*;
import java.awt.*;
import javax.swing.*;
public class Panel extends JPanel
{
public Panel(Prison prison)
{
setup();
build(prison);
}
private void setup()
{
setBorder(BorderFactory.createLineBorder(Color.blue));
setLayout(new BorderLayout(1, 1));
setPreferredSize(new Dimension(350, 190));
}
private void build(Prison prison)
{
JTabbedPane tab = new JTabbedPane();
tab.addTab("Input", null, new InputPanel(), "Input");
tab.addTab("Display", null, new DisplayPanel(), "Display");
add(tab);
}
}
Don't do this.
The whole point of layout managers is to allow dynamic resizing, which is necessary not just for user-resizable windows but also changing texts (internationalization) and different default font sizes and fonts.
If you just use the layout managers correctly, they will take care of panel sizes. To avoid having your components stretched out all over the screen when the user increases the window size, have an outermost panel with a left-aligned FlowLayout and the rest of the UI as its single child - that will give the UI its preferred size and any surplus is filled with the background color.
It looks like you're using a GridLayout, or perhaps a FlowLayout, neither being what you want. You probably want to use a BoxLayout, which respects its components preferred sizes.
final JPanel p = new JPanel();
p.setLayout(new BoxLayout(p, BoxLayout.X_AXIS));
p.add(leftPanel);
p.add(mainPanel);
p.add(rightPanel);
also- that is the preferred size. if you don't want to allow resizing, you can also set the maximum sizes as well.
if you're able, you may want to check out the MIG layout, but BoxLayout is also easy to use and in the java toolkit already.
It's this one.
buttonPanel = new JPanel();
buttonPanel.setSize(new Dimension(30, 100));
Don't let the layout manager adjust your sizes.