Develop Reference

Java: What Layout Manager would be best for a game menu?

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Game Name
Play
Exit
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the above is what my previous game menu looked like. I used the Box Layout to create it but it was very tedious. Is there there a better layout manager that I could use?
here is the code for those that asked of the main pane.
private JButton JB;
private JButton EB;
private JOptionPane JO;
public StartUpWindow(){
super("Pong");
JPanel outside = new JPanel();
JPanel inside = new JPanel();
setLayout(new BorderLayout());
outside.setLayout(new BoxLayout(outside, BoxLayout.LINE_AXIS));
inside.setLayout(new BoxLayout(inside, BoxLayout.PAGE_AXIS));
outside.add(Box.createHorizontalStrut(280));
outside.add(inside);
outside.add(Box.createHorizontalStrut(20));
inside.add(Box.createVerticalStrut(20));
JLabel title = new JLabel(" "+"Pong");
title.setFont( new Font("Serif", Font.BOLD, 40));
inside.add(title);
inside.add(Box.createVerticalStrut(20));
JButton btt1 = new JButton("Start");
Dimension d = new Dimension(200,40);
btt1.setSize(d);
btt1.setMinimumSize(d);
btt1.setMaximumSize(d);
btt1.setPreferredSize(d);
JButton btt2 = new JButton("Credits");
btt2.setSize(d);
btt2.setMinimumSize(d);
btt2.setMaximumSize(d);
btt2.setPreferredSize(d);
JButton btt3 = new JButton("Exit");
btt3.setSize(d);
btt3.setMinimumSize(d);
btt3.setMaximumSize(d);
btt3.setPreferredSize(d);
inside.add(btt1);
btt1.addActionListener(this);
btt1.setActionCommand("start");
inside.add(Box.createVerticalStrut(5));
inside.add(btt2);
btt2.addActionListener(this);
btt2.setActionCommand("credits");
inside.add(Box.createVerticalStrut(5));
inside.add(btt3);
btt3.addActionListener(this);
btt3.setActionCommand("exit");
inside.add(Box.createVerticalStrut(20));
add(outside);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(800,600);
this.setVisible(true);
this.setResizable(false);
this.setLocation(450,200);
inside.setBackground(Color.GRAY);
outside.setBackground(Color.GRAY);
}

I agree that BoxLayout is tedious but I admire its relative simplicity.
Another quick and easy option is to use the "javax.swing.Box" class instead of using a layout manager directly.
Box box = Box.createVerticalBox();
box.add(new JLabel("Game"));
box.add(Box.createVerticalStrut(20));
box.add(new JLabel("Button 1"));
box.add(new JLabel("Button 2"));
JFrame frame = new JFrame();
frame.add(box);
frame.pack();
frame.setVisible(true);
Box offers a number of useful methods. You can use it to create vertical and horizontal boxes, create "struts" to reserve horizontal and vertical space, and create "glue" to fill in available space when the layout grows.
Of course you could also use GridBagLayout, but I tend to reserve it for more complex layouts. Box and his cousin BoxLayout are often good enough for simple layouts and are easy for new programmers who are maintaining the application to understand and debug.

Why not simply use no layout and instead draw everything using a Graphics object?
You could easily achieve this by creating a BufferStrategy bound to the Window object (invoke createBufferStrategy on the latter) then call a few simple methods to easily redraw the screen.
This also means it's simpler to then code the game's display when you're playing it.
BufferStrategy also allows the use of page flipping and other forms of buffering when the application is in fullscreen exclusive mode, allowing it to refresh the screen very rapidly in many applications.

How to re-size JButton

I've bee teaching myself java and following along with the problems in the book. I'm trying to make a display for my calculator. In the example(I did not attach this) the buttons were a smaller size than what mine are and I can't figure out how to reformat them. I tried using the dimension class but it had no affect. Also, I can't get my text at the top of the calculator to align left.
Here is my code:
public class Calculator extends JFrame {
public Calculator() {
setTitle("Calculator");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setSize(300, 300);
setLayout(new BorderLayout());
JPanel numberPanel = new JPanel();
add(numberPanel, BorderLayout.CENTER);
numberPanel.setLayout(new GridLayout(4, 3, 3, 3));
for(int i = 1; i < 10; i++) {
JButton button = new JButton(String.valueOf(i));
numberPanel.add(button);
}
JButton zero = new JButton("" + 0);
JButton dot = new JButton(".");
JButton clear = new JButton("C");
numberPanel.add(zero);
numberPanel.add(dot);
numberPanel.add(clear);
JPanel keyPanel = new JPanel();
add(keyPanel, BorderLayout.EAST);
keyPanel.setLayout(new GridLayout(4, 1, 3, 3));
JButton plus = new JButton("+");
JButton minus = new JButton("-");
JButton times = new JButton("*");
JButton divide = new JButton("/");
keyPanel.add(plus);
keyPanel.add(minus);
keyPanel.add(times);
keyPanel.add(divide);
JPanel equalsPanel = new JPanel();
add(equalsPanel, BorderLayout.SOUTH);
equalsPanel.setLayout(new GridLayout(1, 1));
JButton equals = new JButton("=");
equalsPanel.add(equals);
JPanel textPanel = new JPanel();
add(textPanel, BorderLayout.NORTH);
JTextField inputBox = new JTextField("0.0");
inputBox.setHorizontalAlignment(JTextField.LEFT);
inputBox.setEditable(false);
Font font = new Font("MonoSpaced", Font.BOLD, 20);
inputBox.setFont(font);
textPanel.add(inputBox);
setVisible(true);
}
public static void main(String[] args) {
new Calculator();
}
}
Imports were left off for brevity

GridLayout will laugh at you when you try and set a dimension. It does respect preferred sizes. You should select a layout manager that will respect preferred sizes. Or you can simply pack() (after you add all your components) your frame instead of setSize() and all the components preferred sizes will kick in. (Disclaimer - because of GridLayout though, if you try and resize the frame after that, you components will resize again)
See more at How to use Layout Managers. For a quick view of which layout managers respect preferred sizes and which ones don't, have a look at this post.
A common approach is to nest panels with different layout managers also, as seen here
UPDATE
As mentioned preciously, you should just call pack on the frame instead of set size. With your current code, this would cause the frame to be very small because of the preferred sizes of the components. If you want the buttons to have a bigger preferred size, you can set the font to a bigger font and/or use button.setMargins(new Insets(w,x,y,x)); to make the margins bigger. But it is preferred to pack the frame.

I would recommend using the Window Builder add-on if you’re using Eclipse. This tool will help you with many aspects of Swing. Learn by doing.
WindowBuilder Dowload Link

BorderLayout and JPanel with JLabel

I use:
BorderLayout a = new BorderLayout();
setLayout(a);
JPanel b = new JPanel();
now, if I use:
JButton c = new JButton("Press");
b.add(c);
add("East", b);
my JButton will appear normally. BUT if I say instead:
JLabel c = new JLabel();
c.setBackground(Color.BLACK);
c.setOpaque(true);
add("East", b);
my black JLabel won't appear, which I want to. Why does this happen? Thanks a lot

JLabel c = new JLabel();
You have an empty label, so I'm guessing the size if (0, 0) and there is nothing to paint. Try adding some text.
Also the following is incorrect:
add("East", b);
That is the old way of adding a constraint. Don't use hardcoded values and the constraint is specified second:
add(b, BorderLayout.???);
Read the BorderLayout API or the Swing tutorial on Using a Border Layout for the appropriate constraint.

Adding JPanel to JFrame?

I'm trying to add a JLabel to a JPanel to a JFrame. I set the border for the JPanel, but all I see on the JFrame is a small black square in the center of my frame. Whatever I do I can't change the size or location of it. Please help.
Start main = new Start();
Random random = new Random();
JFrame mainFrame = new JFrame("MainFrame");
JPanel mainPanel = new JPanel();
JLabel welcomeLabel = new JLabel();
mainFrame.add(main);
mainFrame.setLayout(new GridBagLayout());
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setTitle(names[random.nextInt(names.length)]);
mainFrame.pack();
mainFrame.setVisible(true);
mainFrame.setSize(mainFrameX, mainFrameY);
mainFrame.setResizable(false);
mainFrame.setLocationRelativeTo(null);
mainFrame.add(mainPanel);
mainPanel.add(welcomeLabel);
mainPanel.setBorder(new LineBorder(Color.BLACK));
mainPanel.setSize(new Dimension(200, 200));
welcomeLabel.setFont(new Font("Verdana", 1, 20));
welcomeLabel.setLocation(100, 100);
main.start();

Suggestions:
You will want to read the tutorial, Laying out Components, as it will explain how to code with the Swing layout managers, and this information is essential to solve your current problem.
One caveat: I urge you to avoid the temptation to use the null layout as use of it will lead to creation of code that is very hard to maintain or upgrade.
Your JLabel, welcomeLabel, will of course need some text to be visible.
Don't set it's location via setLocation(...) but again use the layout managers to do the dirty work of placing and sizing your components.
You will also want to call pack() and setVisible(true) on your JFrame after adding all initial components.

Hovercraft is right (+1), make sure you understand how the layout managers are working.
The order in which you do things are important, especially when dealing with the top level containers...
Start main = new Start();
Random random = new Random();
JFrame mainFrame = new JFrame("MainFrame");
JPanel mainPanel = new JPanel();
JLabel welcomeLabel = new JLabel();
welcomeLabel.setFont(new Font("Verdana", 1, 20));
mainPanel.add(welcomeLabel);
mainPanel.setBorder(new LineBorder(Color.BLACK));
// Do this first
mainFrame.setLayout(new GridBagLayout());
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setTitle(names[random.nextInt(names.length)]);
// Add your components
mainFrame.add(main);
mainFrame.add(mainPanel);
// Prepare the window for showing, now you have some content.
mainFrame.setResizable(false);
mainFrame.pack();
mainFrame.setVisible(true);
mainFrame.setLocationRelativeTo(null);
main.start();
This will still only produce a small black square in the window, because the JLabel has no content and therefore it's preferred size is going to be (something like) 2x2 (because of the border).
Try adding some text to...
welcomeLabel.setText("Welcome");
And then see the difference

Organizing JPanels and Layouts

So I have the following screen:
And this is my code:
setLayout(new BorderLayout());
JLabel lblTitulo = new JLabel("Sistema Generador de Examenes");
lblTitulo.setFont(new Font("Tahoma", Font.BOLD, 18));
JPanel panel1 = new JPanel();
panel1.setBackground(Color.white);
panel1.add(lblTitulo);
add(panel1, BorderLayout.NORTH);
JButton btnCrear = new JButton("Crear Examen");
JButton btnRendir = new JButton("Rendir Examen");
JButton btnCorregir = new JButton("Corregir Examen");
JButton btnVerCorrecciones = new JButton("Ver Correcciones");
btnCrear.setBounds(15, 100, 450, 35);
btnRendir.setBounds(15, 150, 450, 35);
btnCorregir.setBounds(15, 200, 450, 35);
btnVerCorrecciones.setBounds(15, 250, 450, 35);
JPanel panel2 = new JPanel();
panel2.setBackground(Color.white);
panel2.setLayout(null);
panel2.add(btnCrear);
panel2.add(btnRendir);
panel2.add(btnCorregir);
panel2.add(btnVerCorrecciones);
add(panel2, BorderLayout.CENTER);
1 - I'm using the BorderLayout. Do I need to have 2 JPanels to separate components (JLabel and JButtons) if I want to have the JLabel in the North and the JButtons in the Center? Or is there any way to use just one JPanel?
2 - I want to take out the setBounds used in my JButtons and use some Layout in order to have my JButtons like that in the middle of the screen. How could I do that?

I'm using the BorderLayout. Do I need to have 2 JPanels to separate components (JLabel and JButtons) if I want to have the JLabel in the North and the JButtons in the Center? Or is there any way to use just one JPanel?
Yes, you could use one JPanel and a GridBagLayout with a single column and some Insets to space the buttons from the label.
However, the nested layouts will keep the buttons in the center no matter how you resize the JFrame.
I want to take out the setBounds used in my JButtons and use some Layout in order to have my JButtons like that in the middle of the screen. How could I do that?
The GridBagLayout will space out the buttons with insets.
See this article, Sudoku Solver Swing GUI, for a couple of examples of dialogs that use the GridbagLayout.