import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class TestPanel extends JPanel {
    
    private String data;
    public final static  int cols = 4;
    public final static  int x0 = 10; //x偏移量
    public final static  int y0 = 10; //y偏移量
    public final static  int rowH = 20;//行距
    public final static  int colH = 20;//列间距
    public static void main(String args[]) {
        JFrame f = new JFrame();
        f.getContentPane().add(new TestPanel("abcdadsdfs"));
        f.setSize(400, 400);
        f.setVisible(true);
        
    }
    public TestPanel(String str) {
        this.data = str;
    }
    
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        paintData(g);
    }
    
    private void paintData(Graphics g) {
        
        int x = 0;
        int y = 0;
        int col = 0;
        int row = 0;
        for(int i =0; i < data.length(); i++) {
            col = i % cols;
            row = i / cols;
            x = x0 + col * rowH;
            y = y0 + row * colH;
            g.drawString(data.substring(i, i + 1), x, y);
        }
    }
}

------解决方案--------------------

   public void paint(Graphics g) {
          }
paint 个点不就o了
自己控制好坐标

------解决方案--------------------
用JTable显示不就行了，每个Cell显示三个字母，如果加上HTML的tag还能改变字体和颜色。