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 working with a few people to design a game for a project in class. While making the main menu GUI, I searched all over for some way to get the design the way I wanted (here), but I couldn't figure it out. CardLayout, BoxLayout, BorderLayout, GridLayout, none of those have helped in what I'm trying to do, at least not the way I was implementing each layout. Is there some other layout that could help me with aligning the title text and 4 buttons to the left (horizontally) and aligned with each other vertically. Is it possible to use GridLayout with maybe 5 rows and 3 columns and just fill the 2nd and 3rd columns with nothing? I also want there to be sufficient padding between each object and from the bounds of the window.
This is what I've got so far, but this spreads the width of all the buttons across the entire window:
JLabel title = new JLabel("Inkball", JLabel.LEFT);
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(5, 3, 0, 25));
panel.add(title);
panel.add(playNow);
panel.add(highScore);
panel.add(rules);
panel.add(exitGame);
Container c = this.getContentPane();
c.add(panel, BorderLayout.CENTER);
Start with a BorderLayout.
To this, add a JPanel that uses either a GridLayout or GridBagLayout, to the BorderLayout.WEST position of the parent container, this panel will be used to layout the options on the right
Add a JPanel with a CardLayout to the BorderLayout.CENTER position of the first container. This will will allow you to switch between views based on the selection of the user.
You will need to have the ability to obtain notification about user selection from the "menu pane" and update the "view pane". You simply use a ActionListener, registered to the "menu pane", which acts a proxy for the buttons actions and provide information about what the action menus via the actionCommand property of the JButtons and ActionEvent
Have a look at How to Use Buttons, Check Boxes, and Radio Buttons and Laying Out Components Within a Container for more details
Can i combine Java layouts in same JPanel. I'm stuck with with placing my components on JPanel. It shoudl be like this: JLabel, JButton, JButton , JLabel and new line and same. I used BorderLayout but it wont go to the next row, keep adding components to same row and I need a new row. Ideal sit combined with cardlayout or some other good solution.
EDIT: Solved with GridLayout (0,4) It will do the job till i learn to use GridBaglayout. Thank you for trying to help me.
Yes you can combine layouts.
Using a JPanel you are able to embed other JPanels:
JPanel back = new JPanel(new BorderLayout());
JPanel rows = new JPabel(new GridLayout(3,3));
back.add(rows, BorderLayout.CENTER);
Without seeing your code though it's difficult to know exactly what you are trying to achieve!
Yes you can combine java layouts.
A common pattern I use is BorderLayout first on a frame. The central component expands out, while the other components shrink in. Inside these panels I might have a Flowlayout to show buttons evenly spaced horizontally on top.
Another common approach for forms is using a Gridbaglayout, then adding all the form elements at gridX and gridY positions. I then later can stretch and teak these cells using other constraints in the Gridbaglayout repetoire.
Can you add a screenshot so that we can see what you want to do?
I have got a window that looks like window1 and I would like it to look like window2:
This is my code:
String q = "Have you used GUI before?";
JLabel textLabel2 = new JLabel(
"<html><div style=\"text-align: center;\">" + q + "</html>", SwingConstants.CENTER);
add(textLabel2, BorderLayout.NORTH);
JPanel radioPanel = new JPanel();
add(radioPanel, BorderLayout.CENTER);
JPanel btnPanel = new JPanel();
add(btnPanel, BorderLayout.SOUTH);
For the radio-buttons, I tried to use GridLayout, but it broke the position of "Yes" and "No". And for the "back" and "next" buttons, horizontal alignment did not work (btnPanel.setAlignmentX(RIGHT_ALIGNMENT);), apparently. Any solutions will be highly appreciated, I'm stuck with this bit way too long. Thanks
--EDIT--
That is working perfectly fine:
btnPanel.setLayout(new BoxLayout(btnPanel, BoxLayout.LINE_AXIS));
btnPanel.setBorder(BorderFactory.createEmptyBorder(0, 10, 10, 10));
btnPanel.add(Box.createHorizontalGlue());
so the buttons problem is solved.
However, still can't get the radio-buttons fixed.
--EDIT 2--
Fixed the background for the radio-buttons using setOpaque(false);
What do you mean by it "broke" the position of "yes" and "no" as a GridLayout should work just fine. I'd give it 1 column and 2 (or 0 for variable number of) rows via new GridLayout(0, 1). Be sure that its opaque property is set as false by doing radioPanel.setOpaque(false);. This way it will show the background color of the container that it sits in. You may need to make the JRadioButtons non-opaque as well, I'm not sure.
Your btnPanel could use a BoxLayout and use Box.createGlue() to push the buttons over to the right side.
Most importantly -- if you haven't yet done so, please read the tutorials on use of the Swing layout managers which you can find here.
A couple of things you can do about this. You need to change your LayoutManager. This is not a great task for BorderLayout. You could do nested BoxLayouts. A vertical box that has the vertical fixed height strut, label, vertical fixed height strut, yes radio, vertical fixed strut, no radio, Vertical glue, and the final button panel. Then use your edit in the button panel to horizontally align them. That's one option, but the nesting of the panels is annoying.
Another option go get TableLayout and learn how to use it. TableLayout is one of the best LayoutManagers. It's easy to use, solidly tested, and it makes Swing fun again. You'll never use GridBagLayout ever ever ever again.
http://java.sun.com/products/jfc/tsc/articles/tablelayout/
The final option is use the new GroupLayout. I'm not terribly familiar with it, but it looks pretty easy. And, it doesn't take as much code or nesting unnecessary panels like Box does.
I'm writing a game which uses a border layout with a JPanel using BorderLayout.CENTER. What I'd like to be able to do is sometimes hide this panel and replace it with another panel with different information. I added both to the container and set visibility of one of them to false.
Then later I try:
panel1.setVisible(false);
panel2.setVisible(true);
but this doesn't display the new panel. I just see gray. Any ideas?
TIA
Use a nested JPanel with a CardLayout for that.