Mutator Methods

AP Computer Science A· difficulty 4/5

import java.util.ArrayList;
public static void mod(ArrayList<Integer> list) {
    list.add(99);
    list = new ArrayList<>();
    list.add(7);
}
public static int run() {
    ArrayList<Integer> a = new ArrayList<>();
    a.add(1); a.add(2);
    mod(a);
    return a.size();
}
// Call: System.out.println(run());

What is printed?

A
$2$
B
$3$
check_circle
C
$4$
D
$1$

Explanation

list.add(99) mutates the original list, so a becomes [1,2,99]. Reassigning list locally has no effect. size = 3.

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