How can I set size of a button?

Question

I put my buttons in a JPane with GridLayout. Then I put JPanel into another JPanel with BoxLayout.Y_AXIS. I want buttons in the GridLayout to be square. I use tmp.setSize(30,30) and it does not work. I also try to use new GridLayout(X, Y, 4, 4) but I cannot figure out what X and Y are. So, what is the correct way to do this stuff?

ADDED:

I still cannot solve the problem. Here is the code of what I am trying to do:

import javax.swing.*; import java.awt.*;  public class PanelModel {     public static void main(String[] args) {         JFrame frame = new JFrame("Colored Trails");         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);          JPanel mainPanel = new JPanel();         mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));          JPanel firstPanel = new JPanel();         firstPanel.setLayout(new GridLayout(4, 4));         JButton btn;         for (int i=1; i<=4; i++) {             for (int j=1; j<=4; j++) {                 btn = new JButton();                 btn.setPreferredSize(new Dimension(100, 100));                 firstPanel.add(btn);             }         }          JPanel secondPanel = new JPanel();         secondPanel.setLayout(new GridLayout(5, 13));         for (int i=1; i<=5; i++) {             for (int j=1; j<=13; j++) {                 btn = new JButton();                 btn.setPreferredSize(new Dimension(40, 40));                 secondPanel.add(btn);             }         }          mainPanel.add(firstPanel);         mainPanel.add(secondPanel);         frame.add(mainPanel);          frame.setSize(400,600);         frame.setVisible(true);     } } 

The problem is that Java tries to make width of the firstPanel and secondPanel equal! Moreover, Java tries to to fill all height of the window. How can I remove this behavior?

Answer 1

The following bit of code does what you ask for. Just make sure that you assign enough space so that the text on the button becomes visible

JFrame frame = new JFrame("test"); frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); JPanel panel = new JPanel(new GridLayout(4,4,4,4));  for(int i=0 ; i<16 ; i++){     JButton btn = new JButton(String.valueOf(i));     btn.setPreferredSize(new Dimension(40, 40));     panel.add(btn); } frame.setContentPane(panel); frame.pack(); frame.setVisible(true); 

The X and Y (two first parameters of the GridLayout constructor) specify the number of rows and columns in the grid (respectively). You may leave one of them as 0 if you want that value to be unbounded.

Edit

I've modified the provided code and I believe it now conforms to what is desired:

JFrame frame = new JFrame("Colored Trails"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  JPanel mainPanel = new JPanel(); mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));  JPanel firstPanel = new JPanel(); firstPanel.setLayout(new GridLayout(4, 4)); firstPanel.setMaximumSize(new Dimension(400, 400)); JButton btn; for (int i=1; i<=4; i++) {     for (int j=1; j<=4; j++) {         btn = new JButton();         btn.setPreferredSize(new Dimension(100, 100));         firstPanel.add(btn);     } }  JPanel secondPanel = new JPanel(); secondPanel.setLayout(new GridLayout(5, 13)); secondPanel.setMaximumSize(new Dimension(520, 200)); for (int i=1; i<=5; i++) {     for (int j=1; j<=13; j++) {         btn = new JButton();         btn.setPreferredSize(new Dimension(40, 40));         secondPanel.add(btn);     } }  mainPanel.add(firstPanel); mainPanel.add(secondPanel); frame.setContentPane(mainPanel);  frame.setSize(520,600); frame.setMinimumSize(new Dimension(520,600)); frame.setVisible(true); 

Basically I now set the preferred size of the panels and a minimum size for the frame.