2006 AP CSA FRQ 4: Customer
Topic: Comparable & String Operations
Skills Tested: compareTo logic, String comparison, multi-field comparison, return value conventions
Curriculum Alignment: Unit 2 (Selection/Iteration) (2025-2026 AP CSA)
Points: 9 | Time Estimate: ~22 minutes
Study This Topic: Unit 2: Selection & Iteration Complete Study Guide
Part (a)
Write the compareCustomer method that compares customers first by name, then by ID if names are equal.
Try It First! Attempt to solve this part before viewing the solution.
Solution
public int compareCustomer(Customer other)
{
if (getName().equals(other.getName()))
return getID() - other.getID();
return getName().compareTo(other.getName());
}Part (b)
Alternative implementation using nested conditionals for clarity.
Solution
// Alternative implementation:
public int compareCustomer(Customer other)
{
int nameCompare = getName().compareTo(other.getName());
if (nameCompare != 0)
return nameCompare;
return getID() - other.getID();
}Key Concepts
✓ compareTo returns negative, zero, or positive based on ordering
✓ Use equals() for String equality, compareTo() for ordering
✓ Subtraction trick works for numeric comparison (a - b)
✓ Multi-field comparison: check primary field first, then secondary
Common Mistakes to Avoid
✗ Using == instead of equals() for String comparison
✗ Returning only -1, 0, 1 instead of any negative/zero/positive
✗ Wrong order of comparison (ID before name)
✗ Not using the provided getter methods
Official College Board Resources
About the Author: Tanner Crow is a certified AP Computer Science teacher with 11+ years of experience.
Last updated: January 2026