ArrayList, HashMap

Week 4: Writing classes/14A. Objects in data structures

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+It is often useful to store objects in data structures. 
+An example of how to deal with objects created from the Student class in a list:
+
+ArrayList<Student> students = new ArrayList<>();
+
+Student s1 = new Student("Sam", "12345", 40);
+students.add(s1);
+
+System.out.println(students.get(0).getName());
+
+Program outputs:
+Sam
+ 
+
+
+
+
+
+
+In the same way, you could define, say, a scatterplot where the keys are strings and the values are objects from the 'Course' class above:
+
+HashMap<String, Course> courses = new HashMap<>();
+
+Course oop = new Course("Object-oriented programming", 5);
+
+// let's use course code as the key
+courses.put("TKO_2003", oop);
+
+System.out.println(courses.get("TKO_2003").getIdentifier());
+ 
+
+Program outputs:
+Object-oriented programming
+ 
+
+
+
+
+
+Objects are handled in the data structure in the usual way. 
+The following method takes a list of students as its parameter and returns the total number of credits:
+
+public static int combinedPoints(ArrayList<Student> students) {
+    int points = 0;
+    
+    // The extended for-loop is handy here too
+    for (Student student : students) {
+        points += student.getStudypoints();
+    }
+    return points;
+}
+
+
+
+