diff --git a/build.gradle b/build.gradle
index 0a051a799bb1b9ee8e1f9d7a98b334d54c632f55..ad98374395b88b626171de6869aaef3a8ff850fa 100644
--- a/build.gradle
+++ b/build.gradle
@@ -8,8 +8,6 @@ plugins {
 group 'fr.univ_amu'
 version '1.0-SNAPSHOT'
 
-
-
 checkstyle {
     toolVersion = '10.3.4'
 }
@@ -19,14 +17,11 @@ repositories {
 }
 
 dependencies {
-    checkstyle "com.puppycrawl.tools:checkstyle:10.3.4"
     testImplementation('org.junit.jupiter:junit-jupiter-api:5.9.0',
             'org.assertj:assertj-core:3.23.1')
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.9.0'
 }
 
-
-
 test {
     finalizedBy jacocoTestReport // report is always generated after tests run
 }
@@ -34,8 +29,6 @@ jacocoTestReport {
     dependsOn test // tests are required to run before generating the report
 }
 
-
-
 test {
     useJUnitPlatform()
 }
diff --git a/src/main/java/sample/MyJFrame.java b/src/main/java/sample/MyJFrame.java
deleted file mode 100644
index 4f74f5d940cecd0a4c5c09af48784f3cec66c259..0000000000000000000000000000000000000000
--- a/src/main/java/sample/MyJFrame.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package sample;
-
-import javax.swing.*;
-//import java.awt.*;
-
-public class MyJFrame extends JFrame{
-  public MyJFrame(){
-    setTitle("Main window");
-    setSize(400, 400);
-    setLocationRelativeTo(null);
-    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
-    add(new MyJPanel());
-    setVisible(true);
-  }
-
-  public static void main(String[] args) {
-    MyJFrame app = new MyJFrame();
-  }
-}
diff --git a/src/main/java/sample/MyJavaFrame.java b/src/main/java/sample/MyJavaFrame.java
new file mode 100644
index 0000000000000000000000000000000000000000..4396df4a61c9624884edac2d44ebd85e51218741
--- /dev/null
+++ b/src/main/java/sample/MyJavaFrame.java
@@ -0,0 +1,24 @@
+package sample;
+
+import javax.swing.JFrame;
+
+/**
+ * An extended version of javax.swing.JFrame containing a panel to draw images.
+ */
+public class MyJavaFrame extends JFrame {
+  /**
+   * Constructs a new visible frame.
+   */
+  public MyJavaFrame() {
+    setTitle("Main window");
+    setSize(400, 400);
+    setLocationRelativeTo(null);
+    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    add(new MyJavaPanel());
+    setVisible(true);
+  }
+
+  public static void main(String[] args) {
+    new MyJavaFrame();
+  }
+}
diff --git a/src/main/java/sample/MyJPanel.java b/src/main/java/sample/MyJavaPanel.java
similarity index 51%
rename from src/main/java/sample/MyJPanel.java
rename to src/main/java/sample/MyJavaPanel.java
index 71973abd7f9b91d447d0e9c2d7634e79d5a1deda..c2e8fb2a7223fb8c4052909af9b530e9568a686a 100644
--- a/src/main/java/sample/MyJPanel.java
+++ b/src/main/java/sample/MyJavaPanel.java
@@ -1,19 +1,26 @@
 package sample;
 
-import javax.imageio.ImageIO;
-import javax.swing.*;
-import java.awt.*;
+import java.awt.Graphics;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
+import java.util.Objects;
+import javax.imageio.ImageIO;
+import javax.swing.JPanel;
 
 
-public class MyJPanel extends JPanel {
+/**
+ * An extension of javax.swing.JFrame that can draw images.
+ */
+public class MyJavaPanel extends JPanel {
 
   private BufferedImage image;
+  /**
+   * Constructs a new panel that draw an image.
+   */
 
-  public MyJPanel() {
+  public MyJavaPanel() {
     try {
-      image = ImageIO.read(getClass().getResource("image.png"));
+      image = ImageIO.read(Objects.requireNonNull(getClass().getResource("image.png")));
     } catch (IOException ex) {
       System.out.println("problem! image can't be loaded!");
     }