Add chapters 9-17 for the java book

Java-Kompendium/kap11/Task2.java

@@ -0,0 +1,11 @@
+import javax.swing.JOptionPane;
+
+public class Task2 {
+    public static void main(String[] arguments) {
+        var rawResult = JOptionPane.showInputDialog(null, "Geben Sie eine Zahl ein:");
+        var input = Integer.parseInt(rawResult);
+        Double result = Math.sqrt(input);
+
+        JOptionPane.showMessageDialog(null, result.toString(), "Die Wurzel ist:", JOptionPane.INFORMATION_MESSAGE);
+    }
+}