Provided Code

public class SeatingChart
{
    private Student[][] seats;

    public SeatingChart(ArrayList studentList, int rows, int cols)
    { /* to be implemented in part (a) */ }

    public int countAbsentInRow(int row)
    { /* to be implemented in part (b) */ }
}

// Student class (provided):
// public boolean isAbsent() { ... }

Part A — SeatingChart constructor (6 Points)

Write the constructor. Fill the 2D seats array row by row from studentList. If the list is exhausted before the array is full, remaining slots are null (Java default).

Check Answer Clear

public SeatingChart(ArrayList studentList, int rows, int cols)
{
    seats = new Student[rows][cols];
    int studentIndex = 0;

    for (int r = 0; r < rows; r++)
    {
        for (int c = 0; c < cols; c++)
        {
            if (studentIndex < studentList.size())
            {
                seats[r][c] = studentList.get(studentIndex);
                studentIndex++;
            }
        }
    }
}

Part B — countAbsentInRow (3 Points)

Write countAbsentInRow(). Count and return the number of absent students in the given row. Null slots should not be counted (guard against NullPointerException).

Check Answer Clear

public int countAbsentInRow(int row)
{
    int count = 0;

    for (int c = 0; c < seats[row].length; c++)
    {
        if (seats[row][c] != null && seats[row][c].isAbsent())
        {
            count++;
        }
    }

    return count;
}

Frequently Asked Questions