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
vehicles.add(new Vehicle (10123, "Ford"));
vehicles.add(new Vehicle (10124, "BMW"));
System.out.println(vehicles);
What is the result?
The code attempts to use a TreeSet to store Vehicle objects. TreeSet requires elements to be comparable, either by implementing the Comparable interface or providing a Comparator. The Vehicle class does not implement Comparable, and no Comparator is provided, leading to a ClassCastException at runtime due to the inability to compare Vehicle objects.
answer is D. java.lang.ClassCastException Vehicle cannot be cast to java.lang.Comparable
C is correct in order for the code to run, the class vehicle needs to implement comparable interface, nad override the compareTo method. class Vehicle implements Comparable<Vehicle>{ int vno; String name; public Vehicle (int vno, String name) { this.vno = vno; this.name = name; } public String toString () { return vno + ":" + name; } @Override public int compareTo(Vehicle o) { return this.name.compareTo(o.name); } }
this is incorrect, you can run the code without implementing the interface. Correct answer is D
The answer is C: ClassCastException
D: Exception in thread "main" java.lang.ClassCastException: class test.Vehicle cannot be cast to class java.lang.Comparable (test.Vehicle is in unnamed module of loader 'app'; java.lang.Comparable is in module java.base of loader 'bootstrap')
ClassCastException is thrown at run time
There is no compilation issues, so you do not need to implement the Comparable interface in order for the code to run You will encounter a runtime exception stating the Vehicle class can not be cast to Comparable
Answer is D if this.vno = vno,; is in correct format
D is correct since Vehicle doesn't implement Comparable.
The answer is C, the reason being that in the line "this.vno = vno,;" the variable has "," at the end, this causes the code not to compile. If the line is corrected to "this.vno = vno;" the answer would be D because java.lang.ClassCastException Vehicle cannot be cast to java.lang.Comparable
Correct answer is D. Missing implementing Comparable interface
Change Vehicle class -->>>> class Vehicle implements Comparable<Vehicle> { int vno; String name; public Vehicle(int vno, String name){ this.vno = vno; this.name = name; } public String toString() { return vno + name; } @Override public int compareTo(Vehicle o) { if (vno > o.vno) return 1; else return 0; } }