Multiple choice technology web technology

Given: 3. import java.util.*; 4. public class Mixup { 5. public static void main(String[] args) { 6. Object o = new Object(); 7. // insert code here 8. s.add("o"); 9. s.add(o); 10. } 11. } And these three fragments: I. Set s = new HashSet(); II. TreeSet s = new TreeSet(); III. LinkedHashSet s = new LinkedHashSet(); When fragments I, II, or III are inserted, independently, at line 7, which are true? (Choose all that apply.)

  1. Fragment I compiles

  2. Fragment II compiles

  3. Fragment III compiles

  4. Fragment I executes without exception

  5. Fragment II executes without exception

  6. Fragment III executes without exception
Reveal answer Fill a bubble to check yourself
A,B,C,D,F Correct answer
Explanation

All three fragments compile since raw sets allow adding any Object. At runtime, HashSet and LinkedHashSet only require hashing, so they run without issues. However, TreeSet sorts elements, requiring them to be mutually comparable, throwing a ClassCastException when inserting an Object after a String.

AI explanation

To answer this question, let's go through each fragment and determine if it compiles and executes without exception when inserted at line 7:

Fragment I: Set s = new HashSet();

  • This fragment compiles because HashSet is a valid implementation of the Set interface.
  • It executes without exception because HashSet allows for the addition of objects using the add() method.

Fragment II: TreeSet s = new TreeSet();

  • This fragment compiles because TreeSet is a valid implementation of the Set interface.
  • It executes without exception because TreeSet allows for the addition of objects using the add() method.

Fragment III: LinkedHashSet s = new LinkedHashSet();

  • This fragment compiles because LinkedHashSet is a valid implementation of the Set interface.
  • It executes without exception because LinkedHashSet allows for the addition of objects using the add() method.

Therefore, the correct answers are: A) Fragment I compiles B) Fragment II compiles C) Fragment III compiles D) Fragment I executes without exception F) Fragment III executes without exception

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