Графический вывод матрицы

import java.awt.Font;
import java.awt.Graphics2D;
 
public class Matrix extends javax.swing.JFrame {
 
    Graphics2D gr;
    int a[][] = {{4, -3, 2}, {2, 5, -3}, {5, 6, -2}};
 
    public Matrix() {
        initComponents();
        gr = (Graphics2D) DrawPanel.getGraphics();
    }
 
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
 
        DrawPanel = new javax.swing.JPanel();
        DrawMatrix = new javax.swing.JButton();
 
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
 
        DrawMatrix.setText("Рисовать");
        DrawMatrix.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                DrawMatrixActionPerformed(evt);
            }
        });
 
        javax.swing.GroupLayout DrawPanelLayout = new javax.swing.GroupLayout(DrawPanel);
        DrawPanel.setLayout(DrawPanelLayout);
        DrawPanelLayout.setHorizontalGroup(
            DrawPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(DrawPanelLayout.createSequentialGroup()
                .addGap(80, 80, 80)
                .addComponent(DrawMatrix)
                .addContainerGap(81, Short.MAX_VALUE))
        );
        DrawPanelLayout.setVerticalGroup(
            DrawPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, DrawPanelLayout.createSequentialGroup()
                .addContainerGap(176, Short.MAX_VALUE)
                .addComponent(DrawMatrix)
                .addContainerGap())
        );
 
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(DrawPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(DrawPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
 
        pack();
    }// </editor-fold>
 
    private void DrawMatrixActionPerformed(java.awt.event.ActionEvent evt) {                                         
        gr.setFont(new Font("Courier New", 5, 20));
        gr.drawString("A = ", 10, 100);
        gr.drawArc(150, 45, 20, 100, -100, 200);
        gr.drawArc(60, 45, 20, 100, 80, 190);
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a.length; j++) {
                if (a[j][i]<0) {
                    gr.drawString(String.valueOf(a[j][i]), i * 30 + 70, j * 30 + 70);
                } else {
                    gr.drawString(String.valueOf(a[j][i]), i * 30 + 80, j * 30 + 70);
                }
            }
        }
    }                                        
 
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
 
            public void run() {
                new Matrix().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JButton DrawMatrix;
    private javax.swing.JPanel DrawPanel;
    // End of variables declaration
}