Add chapters 9-17 for the java book

Java-Kompendium/kap9/Coworker.java

@@ -0,0 +1,10 @@
+public class Coworker {
+    public String firstName;
+    public String lastName;
+    public String number;
+    public int salary;
+
+    public void increase(int percent) {
+        this.salary += (salary / 100) * percent;
+    }
+}

Java-Kompendium/kap9/Task.java

@@ -0,0 +1,29 @@
+import java.io.*;
+
+public class Task {
+    public static void main(String[] arguments) {
+        var coworker = new Coworker();
+
+        coworker.firstName = "Sebastian";
+        coworker.lastName = "Mayer";
+        coworker.number = "1234";
+        coworker.salary = 3000;
+
+        System.out.print("Vorname: ");
+        System.out.println(coworker.firstName);
+
+        System.out.print("Nachname: ");
+        System.out.println(coworker.lastName);
+
+        System.out.print("Personalnummer: ");
+        System.out.println(coworker.number);
+
+        System.out.print("Monatslohn: ");
+        System.out.println(coworker.salary);
+
+        coworker.increase(5);
+
+        System.out.print("Monatslohn erhöht um 5%: ");
+        System.out.println(coworker.salary);
+    }
+}