Quiz on Java Wildcard

What does ? represent in Java Generics?

Which wildcard allows both read and write operations?

Which wildcard is best suited for reading data from a generic structure?

What does the wildcard ? super T indicate?

Why is List<?> considered a safe generic structure?

Which of these can be added to a List<? super Number>?

What happens if you try to add an element to List<? extends Number>?

What is the benefit of using wildcards in methods?

What is the output of the following?

List<? extends Number> list = new ArrayList<Integer>();
list.add(10);

Which wildcard allows writing to the list?

Can you instantiate a generic class using a wildcard like `new List<?>();`?

Which wildcard type would you use to accept any list regardless of type?

What is PECS in Java Generics?

Which of these methods correctly uses an upper bounded wildcard?

What is the output of this code?

List<? super Integer> list = new ArrayList<Number>();
list.add(100);
System.out.println(list.get(0));