Java Programming - MCQ Practice Questions

Which of these correctly demonstrates the Producer Extends Consumer Super (PECS) principle?

What will happen with this code? List list = new ArrayList<String>(); list.add(123); // Adding Integer String s = (String) list.get(0);

Consider this code: public <T extends Comparable<T>> T getMax(T a, T b) { return a.compareTo(b) > 0 ? a : b; } What is the benefit of this recursive bound <T extends Comparable<T>>?

Which statement is true about generic inheritance?

What will be the result of this code? List<String> list = new ArrayList<>(); list.add("Hello"); List raw = list; // Unchecked assignment raw.add(123); // Adding Integer to raw type String s = list.get(1);

What will happen when you try to create an array of generic types like 'new ArrayList<String>[10]'?

Consider: Map<String, ? extends List<?>> map = new HashMap<>(); What can you safely retrieve from this map?

What is the key difference between '? extends T' and '? super T' in practical usage?

Which generic declaration allows a method to accept List of any type?

What is the difference between <T extends Comparable<T>> and <T extends Comparable>?

Can you create an instance of generic type parameter directly like: T obj = new T();?

What is the PECS principle in generics?

Which statement about generic constructors is TRUE?

Which statement correctly implements a generic factory method?

Which generic wildcard usage follows the consumer pattern correctly?

What is the compiled signature of this generic method? public <T extends Number & Comparable<T>> void sort(T[] array)

Which of the following represents valid bounded wildcard usage for a method that processes collections?

How would you correctly use generics in a recursive type bound scenario?

What will happen when you compile and run this code? java List<String> strings = Arrays.asList("a", "b", "c"); List raw = strings; raw.add(123); String s = strings.get(3);

Consider this declaration: public static <T> List<T> createList(). Which statement about type inference is correct?