Add chapters 9-17 for the java book

Java-Kompendium/kap11/Task1.java

@@ -0,0 +1,20 @@
+import javax.swing.JOptionPane;
+
+public class Task1 {
+    public static void main(String[] arguments) {
+        var result = JOptionPane.showConfirmDialog(null,
+                "Bestätigen Sie die Eingabe", "Bestätigung", JOptionPane.YES_NO_CANCEL_OPTION);
+
+        switch (result) {
+            case JOptionPane.YES_OPTION:
+                JOptionPane.showMessageDialog(null, "Ja");
+                break;
+            case JOptionPane.NO_OPTION:
+                JOptionPane.showMessageDialog(null, "Nein");
+                break;
+            case JOptionPane.CANCEL_OPTION:
+                JOptionPane.showMessageDialog(null, "Abbrechen");
+                break;
+        }
+    }
+}

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);
+    }
+}