Given the code fragment: 13. list colors = new ArrayList<>(); 14. colors.add("green"); 15. colors.add("red"); 16. colors.add("blue"); 17. colors.add("yellow"); 18. colors.remove(2); 19…

The correct answer is D. [green, red, yellow, cyan]. There is an error in this question's stated answer - tracing the code reveals the output is actually A, not D. Here is the step-by-step trace: | Line | Operation | List state | |------|-----------|------------| | 14–17 | Four add() calls | [green, red, blue, yellow] | | 18 |…

Question

Given the code fragment:
list colors = new ArrayList<>();
colors.add("green");
colors.add("red");
colors.add("blue");
colors.add("yellow");
colors.remove(2);
colors.add(2, "cyan");
System.out.print(colors);

What is the result?

Options

A[green, red, cyan, yellow]
BAn IndexOutOfBoundsException is thrown at runtime.
C[green, blue, yellow, cyan]
D[green, red, yellow, cyan]

How the community answered

(40 responses)

A
8% (3)
B
5% (2)
C
15% (6)
D
73% (29)

Explanation

There is an error in this question's stated answer - tracing the code reveals the output is actually A, not D. Here is the step-by-step trace:

Line	Operation	List state
14–17	Four `add()` calls	`[green, red, blue, yellow]`
18	`remove(2)` - removes element at index 2 ("blue")	`[green, red, yellow]`
19	`add(2, "cyan")` - inserts "cyan at index 2, shifting "yellow" right	`[green, red, cyan, yellow]`
20	`System.out.print(colors)`	prints `[green, red, cyan, yellow]`

Why A is actually correct: ArrayList.remove(int index) removes by position (not by value), so remove(2) deletes "blue". Then add(2, "cyan") inserts at index 2, pushing "yellow" to index 3 - yielding [green, red, cyan, yellow].

Why the distractors fail:

B - no exception is thrown; index 2 is valid at both lines 18 and 19.
C - would require remove(1) (removing "red"), not remove(2).
D - would be correct only if line 19 were colors.add("cyan") (no index argument), which appends to the end.

Memory tip: With ArrayList, add(i, val) inserts (shifts right) and remove(i) deletes (shifts left) - both operate on a zero-based index. When an exam shows both on consecutive lines, redraw the list state after each call to avoid mixing them up.

Note for the exam taker: If this question appears on your actual exam with answer D marked correct, the answer key likely contains a typo on line 19 (it should read colors.add("cyan") without an index). Raise it with your instructor.

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