only for demo use

sudokuExample/src/Main2.java

@@ -0,0 +1,43 @@
+import javax.swing.*;
+import javax.swing.border.EmptyBorder;
+
+public class Main2 {
+
+    public static void main(String[] args) {
+        java.awt.EventQueue.invokeLater(new Runnable() {
+            @Override
+            public void run() {
+
+                JFrame jFrame = new JFrame();
+                jFrame.setVisible(true);
+                jFrame.setBounds(300, 300, 500, 500);
+
+                JPanel yPanel = new JPanel();
+                yPanel.setLayout(new BoxLayout(yPanel, BoxLayout.Y_AXIS));
+                yPanel.setBorder(new EmptyBorder(1, 0, 1,0));
+
+                for (int i = 0; i < 9; i++) {
+
+                    JPanel xPanel = new JPanel();
+                    xPanel.setLayout(new BoxLayout(xPanel, BoxLayout.X_AXIS));
+                    xPanel.setBorder(new EmptyBorder(0, 1, 0,1));
+
+                    for (int j = 0; j < 9; j++) {
+
+                        JTextField jTextField = new JTextField();
+                        jTextField.setColumns(1);
+                        jTextField.setBounds(0, 0, 10, 10);
+
+                        xPanel.add(jTextField);
+
+                    }
+
+                    yPanel.add(xPanel);
+                }
+
+                jFrame.setContentPane(yPanel);
+
+            }
+        });
+    }
+}