AP CSA Unit 4 Day 18: Arraylist Autoboxing
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Unit 4, Data Collections • Cycle 2
Day 18 Advanced Practice • Harder Difficulty
Focus: ArrayList AutoBoxing
Hard
ArrayList AutoBoxing
Advanced Practice Question
Format: ArrayList AutoBoxing
What is the output?
What is the output?
ArrayList list = new ArrayList<>();
list.add(5);
list.add(10);
int x = list.get(0);
System.out.println(x * 2);
Difficulty: Hard |
Topic: ArrayList AutoBoxing |
Cycle: 2 (Advanced)
Why This Answer?
Autoboxing automatically converts int 5 to Integer when adding. Auto-unboxing converts Integer back to int when assigning to x. x=5, x*2=10.
Common Mistake
Watch Out!
Thinking you need explicit conversion between int and Integer.
AP Exam Strategy
Java auto-boxes primitives to wrappers and auto-unboxes wrappers to primitives.
Master This Topic
This Cycle 2 HARD question tests arraylist autoboxing. Review Unit 4 concepts to build mastery of data collections.
- Understanding arraylist autoboxing
- Tracing code execution accurately
- Avoiding common pitfalls
Ready for More Challenges?
Cycle 2 questions prepare you for the hardest AP CSA exam questions.
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