adding hashMap example

src/Main.java

@@ -3,6 +3,7 @@
 import java.util.Scanner;
 import java.util.ArrayList;
 import java.util.HashSet;
+import java.util.HashMap;
 public class Main {
     public static void main(String[] args) {
         //TIP Press <shortcut actionId="ShowIntentionActions"/> with your caret at the highlighted text
@@ -10,6 +11,28 @@ public class Main {
         System.out.println("changes in the merge");
         System.out.println("Hello Mahboobe changing the code online!");
 
+        HashMap<String, Integer> grades = new HashMap<>();
+        grades.put("Mahboobe", 87);
+        grades.put("Chris", 86);
+
+        System.out.println(grades);
+        grades.put("Mahboobe", 90);
+        System.out.println(grades);
+
+        for( String name : grades.keySet()){
+            System.out.println(name + " " + grades.get(name));
+        }
+        System.out.println("check if we have Anne grade: " + grades.containsKey("Anne"));
+        System.out.println("check if we have Mahboobe grade: " + grades.containsKey("Mahboobe"));
+        System.out.println("check if we have 90 grade: " + grades.containsValue(90));
+
+        System.out.println("check if we have Anee grade: " + grades.get("anne"));
+
+        HashMap<String, String> grades2 = new HashMap<>();
+        grades2.put("Mahboobe", "A-");
+        grades2.put("Chris", "B+");
+        System.out.println(grades2);
+
         // ArrayList, Hashset, Hashmap
         // hashSet example
 //        HashSet<String> names = new HashSet<>();