Here is my problem:
I'm creating a window that is responsible for listing a layer, where it displays the layer's
current image (in the form of a ImageIcon as of now), layer's name, and a check box to alter the current on/off state of said layer. The entire thing is supposed to be a knock-off of Paint.NET's Layer Window, as seen here:
My problem has been how to bypass JTable to structure it as so. I figure in the end I might have to resort to just making a dynamic table, but I am wondering if there is a way to make an item/container that can individually display those three components.
The closest I got was using a JLabel with its icon and text properties used, but I had trouble figuring out how to add the check box.
Should I use the layout manager to move the label list to the left, and add a new list filled with check boxes within the pane?
My code is probably as follows:
public class StudioLayerWindow extends JFrame
{
// Objects
JPanel buttonPanel;
JScrollPane layerScroll;
JButton addNewLayer;
JButton deleteCurrentLayer;
JButton duplicateCurrentLayer;
JButton mergeCurrentLayer;
JButton moveCurrentLayerUp;
JButton moveCurrentLayerDown;
JButton layerProperties;
// Constructors & Initializers
public StudioLayerWindow()
{
// Main Window Initialization
this.setTitle("Layers");
this.setType(Type.UTILITY);
this.setSize(200,200);
this.setResizable(false);
this.setAlwaysOnTop(true);
initButtons();
buttonPanel = new JPanel(new GridLayout(1,7));
buttonPanel.setPreferredSize(new Dimension(this.getWidth(), this.getHeight() / 7));
buttonPanel.add(addNewLayer);
buttonPanel.add(deleteCurrentLayer);
buttonPanel.add(duplicateCurrentLayer);
buttonPanel.add(mergeCurrentLayer);
buttonPanel.add(moveCurrentLayerUp);
buttonPanel.add(moveCurrentLayerDown);
buttonPanel.add(layerProperties);
// Code for what I'd add here
layerScroll = new JScrollPane();
this.add(layerScroll , BorderLayout.CENTER);
this.add(buttonPanel , BorderLayout.PAGE_END);
}
The code above does not contain any of my tried solutions, only the basic template I have been at.
Is there any way to make multiple components on a single row?
JList is a generic class.
Create a class which extends JPanel. (Let us call it RowPanel)
Put all elements in it required to be present in a single row (using a horizontal layout)
Create your JList using those panels like
JList<RowPanel> list = new JList<RowPanel>();
You can refer to this for creating ListCellRenderer and ListCellEditor : https://docs.oracle.com/javase/tutorial/uiswing/components/list.html
Note: This should be done if you don't want to use JTable under any circumstances. JTable is a good alternative to this solution.
Hope this helps.
Good luck.
So I have been coding Java for a few months now, and I have been using JOptionPane to display text and variables in my games. I want to upgrade to a single window like a normal game, but I want to only focus on simple buttons and text on the screen. I have tried learning JFrame and ActionListsner, but I failed to completley figure it out. JFrame really confused me.
My question is this: Is there an easier way beside JFrame to just have a window that I can have simple text, buttons and TextFields without the hassle of opening a bunch of windows with JOptionPane, making crap loads of ActionListeners with JFrame or having to get into GUI? If not, where can I find help on how to make games with JFrame?
You should be using a JFrame. Trust me, they aren't that hard to use. Using a JFrame, you could create multiple panels and switch between them using CardLayout.
Since you said you aren't sure about how JFrame works, I gave a short introduction to them at the end of this post. But first, lets first talk about how to solve your problem.
Switching Panels via CardLayout
When you want to switch whats being viewed in the window completely, you're gonna want an entirely different panel for that specific purpose (for example, one for Main Menu, and one for the game). CardLayout was created for this.
You specify a "deck" panel. This panel will hold all the other panels you wanna switch between (cards):
CardLayout layout = new CardLayout();
JPanel deck = new JPanel();
deck.setLayout(layout);
You'll need to maintain a reference to the layout (via a variable) so you can switch between panels.
Now that we have a "deck" panel, we need to add some cards. We do this by creating more JPanels, and specifying a name when we add it to the frame (constraints):
JPanel firstCard = new JPanel();
JPanel secondCard = new JPanel();
deck.add(firstCard, "first");
deck.add(secondCard, "second");
The first card added to the deck will always be the first one to show.
Once you have all your cards added, you can switch between them by calling layout.show(deck, "second");. This is how you use CardLayout to manage multiple panels within your container.
Creating listeners
There's no easier way to manage it. It only gets harder from there (bindings - I highly suggest you look into them). For listeners, there are 2 steps:
Create the listener
Add it to the component
Could be 1 if you created the listener "on the fly" using a lambda:
JButton button = new JButton();
//Java 8+
button.addActionListener(event -> {
//whenever you click the button, code in here triggers
});
For those who don't use Java 8, you will need to use an anonymous class:
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//whenever you click the button, code in here triggers
}
});
Only some components support ActionListener. Anything that extends AbstractButton, like JMenuItem, JButton, JRadioButton, and more will support ActionListeners. JTextField also supports it, even though it's not an AbstractButton. Every component supports KeyListener, though, which can also be used to listen for input events from the user.
If you have any questions about this, let me know and I'll be glad to answer them.
Using Swing Components
JFrame
You initialize a JFrame:
JFrame frame = new JFrame();
You then want to set the defaultCloseOperation, to determine what happens when the window closes:
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
There are different options, but EXIT_ON_CLOSE will terminate your program after closing the window. If you do not set the defaultCloseOperation, then your window will close, but your program will still be running. BIG NO NO. If you don't want the entire program to exit when you close the frame, use DISPOSE_ON_CLOSE.
After you have the close operation, you might be tempted to set the size. This is bad practice. Your frame should size depending on what's inside of it. To do this, you add your components to your frame, then call pack():
JButton button = new JButton("Button");
frame.add(button);
//add other components
frame.pack();
This will ensure your frame sizes to fit what's inside of it. You should always design GUI from the inside out, to ensure you always have enough room for what you need.
Containers
JFrame is a Container. Containers are just components that hold other components. All containers should have a LayoutManager to manage how components are laid out and, if needed, sized. JFrame isn't the only container though. JPanel is actually a container that's meant to be added to another container (or window). You can add things to a JPanel, then add that panel to another container. This is how you keep things neatly organized. Containers are pretty straight forward, so there's not much to talk about.
Content Pane
When you create a JFrame, it comes along with something called the contentPane. It is a JPanel nested within the JFrame. When you do frame.add(button), you'll notice that add actually refers to the contentPane:
//in Container class
public Component add(Component comp) {
addImpl(comp, null, -1); //where it's added
return comp;
}
//In JFrame class (overriding)
protected void addImpl(Component comp, Object constraints, int index) {
if(isRootPaneCheckingEnabled()) {
getContentPane().add(comp, constraints, index); //adds to content pane instead
} else {
super.addImpl(comp, constraints, index); //if root panes were not supported, which they currently are
}
}
You too can grab the contentPane from the frame using
Container pane = frame.getContentPane();
The reason why the contentPane is in Container form is to ensure a strong API (if JPanels were no longer going to be used for this, we wouldn't need to worry about changing the method type of getContentPane). Although, since it IS a JPanel, you can cast it back to it's original form:
JPanel pane = (JPanel) frame.getContentPane();
Although it's usually not needed. Using it as a Container tends to work just fine.
Layouts
JFrame, by default, uses BorderLayout, but you can change this by calling the setLayout method of the container:
FlowLayout layout = new FlowLayout();
frame.setLayout(layout);
Before jumping into layouts, I want to mention that JPanels use FlowLayout as default, except for the frame's default contentPane, which you can also change by doing frame.setContentPane(...). The contentPane uses BorderLayout as default.
Now, lets talk about a couple, starting with the JFrame default: BorderLayout.
Some layouts require what are called constraints, which tell the layout how to handle that specific component that's being added. You specify these constraints when you add the component to the container:
frame.add(button, BorderLayout.SOUTH);
BorderLayout is pretty simple. You have 5 options: NORTH, SOUTH, EAST, WEST, or CENTER. (there are other values such as PAGE_START, which are interchangeable. It's best to just use the easier form)
All constraints for BorderLayout are static field variables that you call similar to how I did. BorderLayout is actually an easy layout to use, seeing how there's not much to it. Even though it's simplicity limits what you can do (you can only put it in a certain position like NORTH), you'd usually combine layouts to get the result you want. This layout can be very powerful when combined with other layouts.
FlowLayout is pretty straight forward, as well as other layouts out there. One of the less straight-forward ones would be GridBagLayout, which can be a really flexible layout. It can also be pretty complex, though, as the documentation even states.
When using GridBagLayout, you need to create a constraints object: GridBagConstraints. To work with GridBagLayout, you set the constraints using the constraints object, then add both the component and the constraints to the container:
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
JButton button = new JButton("yoyoyo");
frame.add(button, gbc);
Even if we don't adjust the constraints, we MUST still specify it when adding a component to the container.
Lets say we had 4 buttons, and we wanted to put them side by side. You would adjust the constraint's gridx and gridy values:
JButton button = new JButton("1");
JButton button2 = new JButton("2");
JButton button3 = new JButton("3");
JButton button4 = new JButton("4");
frame.add(button, gbc);
gbc.gridx = 1; //or gridx += 1, or gridx = 1. gridx starts at 0
frame.add(button2, gbc);
gbc.gridx = 0; //must reset the value back to normal
gbc.gridy = 1;
frame.add(button3, gbc);
gbc.gridx = 1;
//since gridy already == 1, no need to change it
frame.add(button4, gbc);
We can use the same constraints object, as long as we reset values when needed.
GridBagLayout starts centered, and works from the center out, unless you specify otherwise. You cannot skip grid spaces either. Also, as you'll notice, all your buttons will be touching. If you wanted a little space between each component, you can set the insets of the constraints:
int top = 5, left = 5, bottom = 1, right = 1;
gbc.insets.set(top, left, bottom, right);
There is a LOT more to this layout, and sadly I just don't feel this is the best place to give the explanation to it all, seeing how it's already documented (I even added the link).
There are many other layouts out there. Get familiar with as many as you possibly can, then find the ones that'll help suit your needs. Positioning should ALWAYS rely on the LayoutManager that's being used. As for sizing, that kinda depends on the layout you're using.
I would highly recommend using JavaFX. It's a very nice fairly easy to use GUI system with nice looking and customizable controls. JavaFX events (basically ActionListeners) are pretty straightforward as well.
This should get you started: http://docs.oracle.com/javase/8/javafx/get-started-tutorial/get_start_apps.htm#JFXST804
I believe CardLayout is what you're looking for. With it, the programmer can choose which JPanels should be visible in the JFrame. Upon user interaction you can switch the contents of the JFrame without new JFrames or JOptionPanes popping up.
Is there an easier way than using Swing for simple games? Swing has a learning curve, but with the right resources and practice you can learn to build simple GUI applications pretty quickly.
I'm looking to wrap a JPanel when it reaches the 'edge' of the screen using MigLayout. At the moment I have a JScrollPane (which I only want to be enabled vertically). The JScrollPane contains any number of JPanels which are arranged horizontally - when a panel is added so that the JPanel would go off the edge I want it to add to the next line. Is this possible?
This is the code:
public void setupPanels(){
JScrollPane scrollPane = new JScrollPane();
JPanel mainPanel = new JPanel(new MigLayout("insets 2"));
for (Object object : objects){
JPanel subPanel = new JPanel(new MigLayout("insets 0"));
mainPanel.add(subPanel, "alignx left, gapx 2px 5px, gapy 2px 2px, top");
}
scrollPane.setViewportView(mainPanel);
}
Also, to add an extra factor, every time it reaches the edge I need to add a new/different panel (a timeline) - so is there a way of finding out when it is going to wrap onto a new line?
Thanks
MigLayout does not have such a feature. It is based on a grid and while you can use the nogrid option to flow components horizontally or vertically in a cell span, you cannot make them flow into the next row or column.
The java.awt.FlowLayout contained in the JDK wraps the contained components automatically:
JPanel mainPanel = new JPanel(new FlowLayout());
mainPanel.add(subPanel1);
mainPanel.add(subPanel2);
mainPanel.add(subPanel3);
...
The preferred height is off, but there are ways to fix this, see WrapLayout.
As for the second requirement:
Also, to add an extra factor, everytime it reaches the edge I need to
add a new/different panel (A timeline) - so is there a way of finding
out when it is going to wrap onto a new line?
A layout manager should layout components that have already been added to a container, not add new components based on the results of the layout. Adding invisible placeholder components for the timeline after each subpanel that are made visible by the layout manager on demand might work.
You definitely need a custom layout manager to do this. To get started I would recommend to take the source of FlowLayout. In the layoutContainer implementation there is a loop that iterates over all components. After a line wrap, check if the next component is a timeline placeholder component, make it visible and wrap again.
I have a question.
I have one main frame, and to the left i have a sidebar with menus.
My question is, is it possible to make another panel within the main frame,
so that if menu1 is clicked, the related contents should be displayed to the second half of the main frame, and when other menus are pressed then obviously the relevant stuff according to what is selected. its a bit hard to explain, sorry. Has anyone got an idea, whether that is possible in Java with Eclipse?
yes this's pretty possible you have look at CardLayout, this LayoutManager could be provide the simple way how to implement switching betweens JPanel in the JFrame
Yes, you can add 2 JPanels to 1 frame.
JFrame frame = new JFrame();
JPanel pane1 = new JPanel();
JPanel pane2 = new JPanel();
frame.add(pane1, BorderLayout.WEST);
frame.add(pane2, BorderLayout.EAST);
I am using WindowBuilder Pro for eclipse, and I would like to have two Jpanels that perfectly overlap each other. I would then be able to toggle their visibilty based on the selection of a combox box. When I try and acheive this in the gui builder, the first panel gets displaced by the second panel. And advice please?
It is possible using groupLayout, according to the tutorial .
What you must do is add the components to a mother JPanel , and set that panel to use GroupLayout.
Then add the components to the layout as a ParallelGroup in both the horizontal and vertical spacing. This means they will occupy the same X and Y space. Then disable/enable as needed, hiding the JPanels as well.
I believe the way it would work is so:
JPanel panel1, panel2, panel3;
//initialize panel3, etc
panel1=new JPanel();
panel2 = new JPanel();
panel1.add(new JTextField("Panel1"));
panel2.add(new JTextField("PANEL2"));
groupLayout = new GroupLayout(panel3);
panel3.setLayout(groupLayout);
groupLayout.setHorizontalGroup(
groupLayout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(panel1)
.addComponent(panel2)
);
groupLayout.setVerticalGroup(
groupLayout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(panel1)
.addComponent(panel2)
);
panel1.setEnabled(false);
panel1.setVisible(false);
then add a jCheckBox with an ActionPerformed method containing:
if(panel1.isEnabled()) {
panel1.setEnabled(false);
panel1.setVisible(false);
panel2.setEnabled(true);
panel2.setVisible(true);
}else
if(panel2.isEnabled()) {
panel2.setEnabled(false);
panel2.setVisible(false);
panel1.setEnabled(true);
panel1.setVisible(true);
}
That produced the desired behaviour for me. You should be able to switch the JComboBox for the JCheckBox fairly easily.
EDIT: Removed the necessity of having "Jpanel of their own". That should not be the case, and the above method allows you to get the benefits of both GroupLayout and CardLayout.
I would like to have two Jpanels that perfectly overlap each other. I would then be able to toggle their visibilty based on the selection of a combox box
See: How to Use Card Layout for an example that does exactly this.
I would like to have two Jpanels that perfectly overlap each other.
I believe the CardLayout is there exactly for that reason.
Basically, you can nest different panels or 'Cards' using the CardLayout and set the appropriate card to be displayed programmatically (on some event).