GROUNDWORK
Chapter 10 - Records

Name: ________________________________     Date: ______________

Fill in every blank. Where a term is asked for, write the word the course
uses. Where code is asked for, write exact Java. Where output is asked
for, write what the program prints, one line per line.


VOCABULARY
----------

 1. A __________________ is a type of your own that holds a fixed set of
    named values together and cannot be changed after it is made.

 2. In point.x(), the method x() is the record's __________________ for
    its x component: a method named after the component that gives back
    its value.

 3. Real data is usually a collection of records, and in Java that is
    represented as a __________________, such as ArrayList<Student>.

 4. final int LOW_STOCK = 10; is written in capitals, the Java convention
    for a __________________ - a value fixed for the whole program.

 5. The line String state = left == 0 ? "OUT OF STOCK" : left + " left";
    uses a __________________ - an if/else that produces a value rather
    than choosing statements.


READING CODE
------------

 6. What does this print?

        record Point(int x, int y) {}

        record Color(int red, int green, int blue) {}

        void main() {
            Point point = new Point(3, 4);
            Color color = new Color(255, 128, 0);
            IO.println(point.x());
            IO.println(color.green());
            IO.println(color);
        }

    ____________________________________

 7. What does this print?

        record Student(String name, int score) {}

        void main() {
            Student a = new Student("Ada", 88);
            Student b = new Student("Ada", 88);
            Student c = a;
            IO.println(a.equals(b));
            IO.println(a == b);
            IO.println(a == c);
        }

    ____________________________________

 8. What does this print?

        record Cell(int row, int col) {}

        void main() {
            Map<Cell, String> board = new LinkedHashMap<>();
            board.put(new Cell(0, 0), "X");
            board.put(new Cell(1, 1), "O");
            board.put(new Cell(2, 2), "X");
            IO.println(board.get(new Cell(1, 1)));
            IO.println(board.containsKey(new Cell(0, 0)));
            IO.println(board.containsKey(new Cell(0, 1)));
        }

    ____________________________________

 9. What does this print?

        record Range(int lowest, int highest) {}

        Range minMax(int[] numbers) {
            int lowest = numbers[0];
            int highest = numbers[0];
            for (int number : numbers) {
                if (number < lowest) {
                    lowest = number;
                }
                if (number > highest) {
                    highest = number;
                }
            }
            return new Range(lowest, highest);
        }

        void main() {
            int[] numbers = {5, 2, 9, 1};
            Range result = minMax(numbers);
            IO.println(result);
            IO.println(result.highest());
        }

    ____________________________________

10. What does this print?

        record Student(String name, int grade) {}

        Student findStudent(ArrayList<Student> students, String name) {
            for (Student student : students) {
                if (student.name().equals(name)) {
                    return student;
                }
            }
            return null;
        }

        void main() {
            ArrayList<Student> students = new ArrayList<>(List.of(
                    new Student("Ada", 9), new Student("Grace", 10)));
            Student found = findStudent(students, "Alan");
            if (found != null) {
                IO.println(found.grade());
            } else {
                IO.println("Not found.");
            }
            IO.println(findStudent(students, "Grace"));
        }

    ____________________________________


WRITING CODE
------------

11. Complete the line so that it reads the point's x component into a
    variable:
    Point point = new Point(3, 4);
    int x = point.__________________;
    IO.println(x); // 3

12. Complete the declaration of a record that holds a name and a score:
    __________________ Student(String name, int score) {}

13. Complete the line so that an empty list is put in for a category the
    map does not have yet, before an item is added to that category's
    list:
    Map<String, ArrayList<Item>> groups = new TreeMap<>();
    if (!groups.__________________(item.category())) {
        groups.put(item.category(), new ArrayList<>());
    }
    groups.get(item.category()).add(item);


WHY IT WORKS
------------

14. A method handed a record cannot change any of its components, because
    a record is __________________.

15. A map looks up a key by its value, as .equals compares it, and two
    records with the same components are __________________, so
    new Cell(1, 1) finds the entry put in under another new Cell(1, 1).

16. Sorting a list of student records by score keeps each student's name
    and score correctly matched, because every field for one student lives
    together inside a single __________________, so sorting only reorders
    those units in the list, not the values inside them.