String Method Tips and Common Mistakes
String methods come up throughout AP CSA, and Part B of the first free-response question on the AP Exam requires students to use them. They can be tricky, since small details are easy to mix up. A few mistakes show up often:
The second number in substring(from, to) is where the substring stops, and that character isn’t included. "costume".substring(1, 4) returns "ost". To get a single character as a String, students can use substring(index, index + 1).
Strings can’t be changed after they’re created. Calling word.substring(2); on its own line does nothing useful, because the result has to be stored, as in word = word.substring(2);.
indexOf returns -1 when it doesn’t find a match, so students should check for that before using the result as an index. Valid indexes run from 0 to length() - 1, and anything outside that range causes a StringIndexOutOfBoundsException.
To compare the text in two Strings, students should use equals. The == operator checks whether two variables refer to the same object, so it can return false even when the text matches.
AP CSA Question of the Day
As you're preparing for your next lesson, don’t forget to check out the CodeHS AP CSA Question of the Day (QOTD)!
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AP CSA Project of the Month
This month's featured project is The Monty Hall Simulator. In this project, students will recreate the classic paradox from Let's Make A Deal. They start off recreating the final pick-a-door option and then extend this with a simulator to simulate thousands of iterations as they examine this mathematical puzzle. Students will use loops and conditional statements to help solve this problem. This project should take students about 3 hours and includes autograders.
College Board Student Registration Deadline
Just a quick reminder that the College Board’s deadline for full-year AP exam orders is November 13th. Exams ordered after that date have a $40 late fee. Many schools set an earlier deadline so their AP coordinator has time to submit orders, so encourage students to check with their coordinator and register soon!
Free PD for AP CSA Teachers
Missed September’s AP CSA Professional Learning Community? The recording is ready to watch whenever it fits your schedule.
AP CSA Professional Learning Community (PLC) - Watch Now
Request a Visit From CodeHS for CSEdWeek
From November 30th – December 11th, CodeHS team members are visiting classrooms to celebrate Computer Science Education Week! Request a visit from the team or explore Hour of Code and Hour of AI activities you can assign to students during CSEdWeek.
Important Platform Updates
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