Problem of the Day

Thursday, December 18, 2025

Problem:

The String Array students holds the names of a series of students who are seated in order in a single line in a classroom.

String[] students = {"Aaron", "Bobby", "Caroline", "Darlene"};

... for example, represents four students seated left-to-right in the classroom.

What does the following code segment do?

ArrayList vals = new ArrayList();
for (int i = 0; i < students.length; i++) { vals.add(i); }
while (true)
{
    int j = (int) (Math.random() * vals.size());
    System.out.println("Work with " + students[vals.remove(j)]);
    if (vals.size() == 0)
        for (int i = 0; i < students.length; i++) { vals.add(i); }    
}

1. Chooses a random student from the list each time, possibly selecting the same student twice in a row
2. Chooses a random student from the list each time, with no student selected twice before all students have been selected once
3. Repeatedly goes through the list of students from left-to-right
4. Repeatedly goes through the list of students from right-to-left

Show solution: