What is the result of the given Java code? | 1Z0-809 Exam Question
Question
Given: class Vehicle{ int vno; String name; public Vehicle (int vno, String name){ this.vno = vno,; this.name = name; } public String toString (){ return vno + ":" + name; } } and this code fragment: Set<Vehicle>vehicles = new TreeSet <> (); vehicles.add(new Vehicle (10123, "Ford")); vehicles.add(new Vehicle (10124, "BMW")); System.out.println(vehicles); What is the result?
Answers
Explanations
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A. B. C. D.D.
The given code defines a class Vehicle with two instance variables vno and name. The class has a constructor that initializes these variables and a toString() method that returns a string representation of the Vehicle object.
In the code fragment, a TreeSet of Vehicle objects is created and two Vehicle objects are added to it using the add() method. The TreeSet is then printed using the System.out.println() method.
The TreeSet is a collection that stores its elements in sorted order. In order to maintain the sorted order, the Vehicle class must implement the Comparable interface and provide an implementation for the compareTo() method. If the compareTo() method is not implemented, a ClassCastException will be thrown at runtime.
In this case, the Vehicle class does not implement the Comparable interface, so the TreeSet will use the default ordering, which is based on the natural order of the elements. Since Vehicle objects are not comparable, a ClassCastException will be thrown at runtime.
Therefore, the correct answer is option D: A ClassCastException is thrown at runtime.
