habe die projekt struktur geändert und main in eine klasse exportiert.

sudokuExample/src/GameField.java → src/main/java/src/GameField.java

@@ -1,3 +1,5 @@
+package src;
+
 import javax.swing.*;
 import javax.swing.border.LineBorder;
 import java.awt.*;

sudokuExample/src/Main.java → src/main/java/src/Main.java

@@ -1,7 +1,7 @@
+package src;
+
 import javax.swing.*;
 import java.awt.*;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 import java.lang.String;
 
 public class Main {
@@ -23,86 +23,14 @@ public class Main {
             @Override
             public void run() {
 
-                JFrame main = new JFrame();
-                main.setLayout(null);
-                main.setVisible(true);
-                main.setBounds(300, 200, 500, 600);
-                main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
-
-                JPanel rootPanel = new JPanel();
-                rootPanel.setVisible(true);
-                rootPanel.setBounds(0, 0, 500, 500);
-                rootPanel.setBackground(Color.LIGHT_GRAY);
-                rootPanel.setLayout(null);
-
-                GameField gameField = new GameField(360);
-                gameField.setBounds(70, 50, 360, 360);
-                rootPanel.add(gameField);
-
-                main.setContentPane(rootPanel);
-
-                JPanel numberPanel = new JPanel();
-                numberPanel.setVisible(true);
-                numberPanel.setBounds(100, 450, 300, 30);
-                rootPanel.add(numberPanel);
-
-                for (int i = 1, j=0; i < 10; i++) {
-                        JLabel numberi= new JLabel();
-                        numberi.setText(""+i);
-                        numberi.setBounds(5+j, 5, 20, 20);
-                        numberPanel.setLayout(null);
-
-                        JPanel ni = new JPanel();
-                        ni.setBounds(5+j, 5, 20, 20);
-                        ni.setVisible(true);
-                        ni.setBackground(Color.pink);
-                        ni.add(numberi);
-                        numberPanel.add(ni);
-                        j=j+25;
-                }
-
-                JLabel number10= new JLabel();
-                number10.setText(" ");
-                number10.setBounds(250, 5, 20, 20);
-                numberPanel.setLayout(null);
-
-                JPanel n10 = new JPanel();
-                n10.setBounds(250, 5, 20, 20);
-                n10.setVisible(true);
-                n10.setBackground(Color.pink);
-                n10.add(number10);
-                numberPanel.add(n10);
-
-
-
-                JButton back = new JButton();
-                back.setVisible(true);
-                back.setBounds(5, 5, 100, 25);
-                rootPanel.add(back);
-                back.setText("Back");
-
-                JButton newButton  = new JButton();
-                newButton.setVisible(true);
-                newButton.setBounds(395, 5, 100, 25);
-                newButton.setText("New");
-                rootPanel.add(newButton);
-
-                JButton retryButton = new JButton();
-                retryButton.setVisible(true);
-                retryButton.setText("Retry");
-                retryButton.setBounds(5, 525, 100, 25);
-                rootPanel.add(retryButton);
-
-                JButton correctButton = new JButton();
-                correctButton.setVisible(true);
-                correctButton.setText("Correct");
-                correctButton.setBounds(395, 525, 100, 25);
-                rootPanel.add(correctButton);
+                MainFrame mainFrame = new MainFrame();
+                mainFrame.run();
 
             }
         });
     }
 
+
 //    protected static JPanel setupGameField(int widthHeight) {
 //
 //        int nrOfFields = 9;

src/main/java/src/MainFrame.java

@@ -0,0 +1,85 @@
+package src;
+
+import javax.swing.*;
+import java.awt.*;
+
+public class MainFrame extends JFrame {
+
+    public void run() {
+
+        this.setLayout(null);
+        this.setVisible(true);
+        this.setBounds(300, 200, 500, 600);
+        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+
+        JPanel rootPanel = new JPanel();
+        rootPanel.setVisible(true);
+        rootPanel.setBounds(0, 0, 500, 500);
+        rootPanel.setBackground(Color.LIGHT_GRAY);
+        rootPanel.setLayout(null);
+
+        GameField gameField = new GameField(360);
+        gameField.setBounds(70, 50, 360, 360);
+        rootPanel.add(gameField);
+
+        this.setContentPane(rootPanel);
+
+        JPanel numberPanel = new JPanel();
+        numberPanel.setVisible(true);
+        numberPanel.setBounds(100, 450, 300, 30);
+        rootPanel.add(numberPanel);
+
+        for (int i = 1, j=0; i < 10; i++) {
+            JLabel numberi= new JLabel();
+            numberi.setText(""+i);
+            numberi.setBounds(5+j, 5, 20, 20);
+            numberPanel.setLayout(null);
+
+            JPanel ni = new JPanel();
+            ni.setBounds(5+j, 5, 20, 20);
+            ni.setVisible(true);
+            ni.setBackground(Color.pink);
+            ni.add(numberi);
+            numberPanel.add(ni);
+            j=j+25;
+        }
+
+        JLabel number10= new JLabel();
+        number10.setText(" ");
+        number10.setBounds(250, 5, 20, 20);
+        numberPanel.setLayout(null);
+
+        JPanel n10 = new JPanel();
+        n10.setBounds(250, 5, 20, 20);
+        n10.setVisible(true);
+        n10.setBackground(Color.pink);
+        n10.add(number10);
+        numberPanel.add(n10);
+
+
+
+        JButton back = new JButton();
+        back.setVisible(true);
+        back.setBounds(5, 5, 100, 25);
+        rootPanel.add(back);
+        back.setText("Back");
+
+        JButton newButton  = new JButton();
+        newButton.setVisible(true);
+        newButton.setBounds(395, 5, 100, 25);
+        newButton.setText("New");
+        rootPanel.add(newButton);
+
+        JButton retryButton = new JButton();
+        retryButton.setVisible(true);
+        retryButton.setText("Retry");
+        retryButton.setBounds(5, 525, 100, 25);
+        rootPanel.add(retryButton);
+
+        JButton correctButton = new JButton();
+        correctButton.setVisible(true);
+        correctButton.setText("Correct");
+        correctButton.setBounds(395, 525, 100, 25);
+        rootPanel.add(correctButton);
+    }
+}

sudokuExample/src/Notes.java → src/main/java/src/Notes.java

@@ -1,3 +1,5 @@
+package src;
+
 import javax.swing.*;
 import java.awt.*;
 

sudokuExample/src/Tests.java → src/main/java/src/Tests.java

@@ -1,3 +1,5 @@
+package src;
+
 public class Tests {
 
     public static void main(String[] args) {

src/test/java/GameFieldTest.java

@@ -1,4 +1,6 @@
 import org.junit.jupiter.api.Test;
+import src.GameField;
+import src.Notes;
 
 import static org.junit.jupiter.api.Assertions.*;
 

src/test/java/MainTest.java

@@ -1,6 +1,5 @@
-import org.junit.Test;
-
-import javax.swing.*;
+import src.GameField;
+import src.Main;
 
 import static org.junit.jupiter.api.Assertions.*;
 

src/test/java/NotesTest.java

@@ -1,4 +1,5 @@
 import org.junit.jupiter.api.Test;
+import src.Notes;
 
 import javax.swing.*;