GOOD

Test.java

@@ -0,0 +1,6 @@
+public class Test extends JPanel {
+    public Test(){}
+    public void paint(Graphics g){
+        g.drawArc(125, 100, 550, 550, 0, 360);
+    }
+}

Test2.java

@@ -0,0 +1,8 @@
+public class Test2 extends JFrame {
+    public Test2(){
+      super("Test");
+      setSize(1280, 720);
+      add(new Test());
+    setVisible(true);
+ }
+}