I’m begining a little project to create a simple checkers game. However it’s been a long time since I’ve used the java GUI tools. The goal of the code at this point is to draw the initial board (red pieces at top, black at bottom). However all I get when I run the code is a blank frame. I’m also a little uncertain if my circle drawing code will do what I want (ie create solid red or black circles inside certain squares) Here is the code. Thanks in advance for any help/suggestions
EDIT: I should probably alternate drawing blue and gray squares or else the thing will probably just be a giant blue blob, however I’ll settle for a giant blue blob at this point :p
import javax.swing.*;
import java.awt.*;
public class CheckersServer
{
public static class Board
{
private JFrame frame = new JFrame();
private JPanel backBoard = new JPanel();
Board()
{
frame.setSize(905,905);
backBoard.setSize(900,900);
frame.setTitle("Checkers");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
backBoard.setVisible(true);
boardSquare bs;
String type = null;
//Filling in Red Side
for (int i = 0; i <=1; i++)
{
for(int j = 0; j < 9; j++)
{
if(j % 2 == 0)
{
type = "Red";
}
else
{
type = "Blank";
}
bs = new boardSquare(100*j,100*i,type);
backBoard.add(bs);
}
}
//Filling in empty middle
type = "Blank";
for (int i = 2; i < 7; i++)
{
for(int j = 0; j < 9; j++)
{
bs = new boardSquare(100*j,100*i,type);
backBoard.add(bs);
}
}
//Filling in Black side
for (int i = 7; i < 9; i++)
{
for(int j = 0; j < 9; j++)
{
if(j % 2 != 0)
{
type = "Black";
}
else
{
type = "Blank";
}
bs = new boardSquare(100*j,100*i,type);
backBoard.add(bs);
}
}
backBoard.repaint();
frame.add(backBoard);
frame.repaint();
}
private class boardSquare extends JComponent
{
private int x; //x position of the rectangle measured from top left corner
private int y; //y position of the rectangle measured from top left corner
private boolean isBlack = false;
private boolean isRed = false;
public boardSquare(int p, int q, String type)
{
x = p;
y = q;
if (type.equals("Black"))
{
isBlack = true;
isRed = false;
}
else if (type.equals("Red"))
{
isRed = true;
isBlack = false;
}
else if (type.equals("Blank"))
{
isBlack = false;
isRed = false;
}
}
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
Rectangle box = new Rectangle(x,y,100,100);
g2.draw(box);
g2.setPaint(Color.BLUE);
g2.fill(box);
if(isBlack)
{
g2.fillOval(x, y,100 ,100 );
g2.setColor(Color.black);
g2.drawOval(x, y, 100, 100);
}
else if(isRed)
{
g2.fillOval(x, y,100 ,100 );
g2.setColor(Color.red);
g2.drawOval(x, y, 100, 100);
}
}
}
}
public static void main(String[] args)
{
Board game = new Board();
}
}
You have several issues.
Java UI is layout-based, which means that when you add a component to a parent, the parent’s layout determines where the child component will be placed. You don’t have any code to set up the layout, and so your application is using the defaults (FlowLayout is the default, and this may work in your case, as long as your JFrame and children are the appropriate size).
The bigger problems are in your boardSquare class. By default, JPanels have a dimension of 10×10. You aren’t specifying the size, and so all your squares are 10×10. You need to tell the squares how big they are. You can do this in the boardSquare constructor:
Finally, in your drawing code, you are doing an offset of x,y when drawing the squares and circles. This is an offset from the top-left corner of the component. Your components (after setting the size) will be 100×100 pixels. But if your x,y are greater than these values, you will be drawing outside of the bounds of the component. Instead, these values should be set to 0,0 because that is the top-left corner of the component you are drawing in.
By just setting the preferred size of the squares and setting x,y to 0, I was able to get the squares drawing in the frame, though it wasn’t pretty. You will need to work on setting the correct layout before it will be laid out correctly.