diff --git a/Advanced-Java/src/collections/ListDemo.java b/Advanced-Java/src/collections/ListDemo.java
index 9dc30aa..238f8a9 100644
--- a/Advanced-Java/src/collections/ListDemo.java
+++ b/Advanced-Java/src/collections/ListDemo.java
@@ -89,5 +89,9 @@ public static void main(String[] args) {
         numbersLinkedList.forEach(System.out::println);
 
         System.out.println(numbersLinkedList.contains(3));
+
+        int[] nums = new int[5];
+        Arrays.fill(nums, 1);
+        Arrays.sort(nums);
     }
 }
diff --git a/Advanced-Java/src/collections/Person.java b/Advanced-Java/src/collections/Person.java
new file mode 100644
index 0000000..9e669e4
--- /dev/null
+++ b/Advanced-Java/src/collections/Person.java
@@ -0,0 +1,48 @@
+package collections;
+
+// Entity / model / POJO
+public class Person implements Comparable<Person>{
+    String name;
+    int age;
+
+    public Person(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "Person{" +
+                "name='" + name + '\'' +
+                ", age=" + age +
+                '}';
+    }
+
+    @Override
+    public int compareTo(Person o) {
+        if (this.getName().compareTo(o.getName()) == 0) {
+            if (this.getAge() > (o.getAge())) return 1;
+            else return -1;
+        } else if (this.getName().compareTo(o.getName()) > 0){
+            return 1;
+        } else {
+            return -1;
+        }
+    }
+}
diff --git a/Advanced-Java/src/collections/QueueDemo.java b/Advanced-Java/src/collections/QueueDemo.java
index 3429a8a..74a257b 100644
--- a/Advanced-Java/src/collections/QueueDemo.java
+++ b/Advanced-Java/src/collections/QueueDemo.java
@@ -27,6 +27,26 @@ public static void main(String[] args) {
         customQueue2.addLast("Ramadan");
         customQueue2.addLast("Mubarak");
         customQueue2.forEach(System.out::println);
+
+        Queue<Person> people = new PriorityQueue<>(Comparator.comparingInt(Person::getAge));
+        Person ramadan = new Person("Ramadan", 34);
+        Person dawan = new Person("Dawan", 32);
+        Person sheriffo = new Person("Sheriffo", 33);
+        Person ramadan2 = new Person("Ramadan", 31);
+        people.add(ramadan);
+        people.add(dawan);
+        people.add(sheriffo);
+        people.add(ramadan2);
+
+        System.out.println("PQ for Person");
+//        people.forEach(System.out::println);
+
+        while(true)
+        {
+            Person e = people.poll();
+            System.out.println(e);
+            if(e == null) break;
+        }
     }
 }
 
diff --git a/Advanced-Java/src/collections/SetDemo.java b/Advanced-Java/src/collections/SetDemo.java
index 0c30837..17ced48 100644
--- a/Advanced-Java/src/collections/SetDemo.java
+++ b/Advanced-Java/src/collections/SetDemo.java
@@ -1,7 +1,9 @@
 package collections;
 
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.Set;
+import java.util.TreeSet;
 
 /**
  * 1. Unordered
@@ -15,15 +17,54 @@ public static void main(String[] args) {
         numbersSet.add(2);
         numbersSet.add(3);
         numbersSet.add(5);
+        numbersSet.add(1);
+        numbersSet.add(0);
 
-        for (int i = 0; i < 10; i++) {
-            numbersSet.add(i);
-        }
-
-        numbersSet.add(5);
+//        for (int i = 0; i < 10; i++) {
+//            numbersSet.add(i);
+//        }
+//
+//        numbersSet.add(5);
 
+        System.out.println("HashSet");
         numbersSet.forEach(System.out::println);
 
-        System.out.println(numbersSet.contains(4));
+//        System.out.println(numbersSet.contains(4));
+
+        Set<Integer> numbersLinkedSet = new LinkedHashSet<>(32, .5f);
+        numbersLinkedSet.add(3);
+        numbersLinkedSet.add(2);
+        numbersLinkedSet.add(3);
+        numbersLinkedSet.add(5);
+        numbersLinkedSet.add(1);
+        numbersLinkedSet.add(0);
+
+
+        System.out.println("LinkedHashSet");
+        numbersLinkedSet.forEach(System.out::println);
+
+        Set<Integer> numbersTreeSet = new TreeSet<>();
+        numbersTreeSet.add(3);
+        numbersTreeSet.add(2);
+        numbersTreeSet.add(3);
+        numbersTreeSet.add(5);
+        numbersTreeSet.add(1);
+        numbersTreeSet.add(0);
+
+        System.out.println("TreeSet");
+        numbersTreeSet.forEach(System.out::println);
+
+        Set<Person> people = new TreeSet<>();
+        Person ramadan = new Person("Ramadan", 34);
+        Person dawan = new Person("Dawan", 32);
+        Person sheriffo = new Person("Sheriffo", 33);
+        Person ramadan2 = new Person("Ramadan", 31);
+        people.add(ramadan);
+        people.add(dawan);
+        people.add(sheriffo);
+        people.add(ramadan2);
+
+        System.out.println("TreeSet for Person");
+        people.forEach(System.out::println);
     }
 }
diff --git a/Advanced-Java/src/collections/mapDemo.java b/Advanced-Java/src/collections/mapDemo.java
new file mode 100644
index 0000000..ddac4ae
--- /dev/null
+++ b/Advanced-Java/src/collections/mapDemo.java
@@ -0,0 +1,47 @@
+package collections;
+
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class mapDemo {
+
+    public static void main(String[] args) {
+        Map<String, Integer> personAge = new HashMap<>();
+        personAge.put("Ramadan", 32);
+//        personAge.put("Ramadan", 34);
+        personAge.put("Dawan", 31);
+        personAge.put("Sheriffo", 35);
+
+//        personAge.keySet().forEach(System.out::println);
+//        personAge.values().forEach(System.out::println);
+
+        // iterative approach
+//        for (Map.Entry<String, Integer> entry: personAge.entrySet()) {
+//            System.out.println(entry.getKey() + " : " + entry.getValue());
+//        }
+
+        // functional
+        System.out.println("*** HashMap ***");
+        personAge.forEach((k, v) -> System.out.println(k + " : " + v));
+
+        Map<String, Integer> personAgeLinkedMap = new LinkedHashMap<>();
+        personAgeLinkedMap.put("Ramadan", 32);
+//        personAge.put("Ramadan", 34);
+        personAgeLinkedMap.put("Dawan", 31);
+        personAgeLinkedMap.put("Sheriffo", 35);
+
+        System.out.println("*** LinkedHashMap ***");
+        personAgeLinkedMap.forEach((k, v) -> System.out.println(k + " : " + v));
+
+        Map<String, Integer> personAgeOrderedMap = new TreeMap<>();
+        personAgeOrderedMap.put("Ramadan", 32);
+//        personAge.put("Ramadan", 34);
+        personAgeOrderedMap.put("Dawan", 31);
+        personAgeOrderedMap.put("Sheriffo", 35);
+
+        System.out.println("*** TreeMap ***");
+        personAgeOrderedMap.forEach((k, v) -> System.out.println(k + " : " + v));
+    }
+}