💻AP Computer Science A
💻AP Computer Science A
FRQ 1 – Methods and Control Structures
Unit 1: Using Objects and Methods
Practice FRQ 1 of 191/19
1. This question involves managing student enrollment for a computer science course using the CourseEnrollment class. The CourseEnrollment class maintains a roster of enrolled students and tracks the number of seats remaining. A helper method, checkPrereq, is provided to determine if a student meets the prerequisites for the course.
</>Java
public class CourseEnrollment
{
/** The number of seats currently available in the course */
private int seatsRemaining;
/** The list of enrolled students, names separated by a single space */
private String roster; // Initialized to "" in the constructor
/**
* Initializes the course with a specified number of seats and an empty roster.
* Precondition: seats > 0
*/
public CourseEnrollment(int seats)
{ /* implementation not shown */ }
/**
* Returns true if the student with the given name meets the
* prerequisites for the course, false otherwise.
* Precondition: name is not null
*/
public boolean checkPrereq(String name)
{ /* implementation not shown */ }
/**
* Enrolls a student if there are seats available and the student
* meets the prerequisites, as described in part (a).
* Precondition: name is not null
*/
public boolean enrollStudent(String name)
{ /* to be implemented in part (a) */ }
/**
* Processes a string of names from a waitlist and attempts to enroll
* each student, as described in part (b).
* Precondition: names ends with a space.
*/
public int processWaitList(String names)
{ /* to be implemented in part (b) */ }
/* There may be instance variables, constructors, and methods
that are not shown. */
}a. Write the enrollStudent method, which attempts to enroll a student with the given name. The method should verify that seatsRemaining is greater than 0 and that the student meets the prerequisites by calling the checkPrereq method.
If both conditions are met, the method should:
1. Decrease seatsRemaining by 1.
2. Append the name followed by a space to the instance variable roster.
3. Return true.
1. Decrease seatsRemaining by 1.
2. Append the name followed by a space to the instance variable roster.
3. Return true.
Otherwise, the method should return false and make no changes to the instance variables.
You must use the checkPrereq method to determine eligibility. The roster string stores names separated by a single space.
Example 1
Assume a CourseEnrollment object has been created with 2 seats remaining and an empty roster. Consider the following calls to enrollStudent.
| Method Call | checkPrereq(name) | seatsRemaining (before) | Return Value | seatsRemaining (after) |
|---|---|---|---|---|
| enrollStudent("Alex") | true | 2 | true | 1 |
| enrollStudent("Sam") | false | 1 | false | 1 |
| enrollStudent("Jordan") | true | 1 | true | 0 |
| enrollStudent("Casey") | true | 0 | false | 0 |
After these calls, the instance variable roster would contain "Alex Jordan ".
Complete the enrollStudent method.
/** * Enrolls a student if there are seats available and the student * meets the prerequisites, as described in part (a). * Precondition: name is not null */ public boolean enrollStudent(String name)
b. Write the processWaitList method, which attempts to enroll students from a string of names. The parameter names contains student names separated by a single space. The string is guaranteed to end with a space.
The method should:
1. Traverse the names string to extract each individual student name.
2. Call enrollStudent for each name extracted.
3. Return the total number of students successfully enrolled.
1. Traverse the names string to extract each individual student name.
2. Call enrollStudent for each name extracted.
3. Return the total number of students successfully enrolled.
Example 1
Assume a CourseEnrollment object has 2 seats remaining. Also assume checkPrereq returns true for "Alex" and "Jordan", but false for "Sam".
| Method Call | Return Value |
|---|---|
| processWaitList("Alex Sam Jordan ") | 2 |
The method processes "Alex" (enrolled), then "Sam" (not enrolled due to prereq), then "Jordan" (enrolled). The method returns 2.
Complete the processWaitList method. You must use enrollStudent appropriately in order to receive full credit.
/** * Processes a string of names from a waitlist and attempts to enroll * each student, as described in part (b). * Precondition: names ends with a space. */ public int processWaitList(String names)
