Java Programming - MCQ Practice Questions

What is the primary advantage of using generics in Java?

In the declaration 'List<? extends Number> list', what types can be added to this list at runtime?

Which statement correctly uses the lower-bounded wildcard in generics?

Which generic declaration would allow storing both String and Integer in the same collection?

What does the PECS principle stand for in generics context?

Which of the following will compile successfully?

In a generic class 'class Box<T extends Comparable<T>>', what constraint is placed on T?

What is the output of this code snippet? ArrayList<String> list = new ArrayList<>(); list.add("Java"); Object obj = list.get(0); String str = (String) obj; System.out.println(str.length());

Which generic wildcard usage is INCORRECT?

What is the relationship between raw types and generics in Java?

Consider the method: public static <T> T getFirst(List<T> list) { return list.get(0); } How would you call this method for a List<String>?

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

In the interface declaration 'interface Pair<K, V>', how many type parameters does it have?

What is the significance of the '&' operator in generic bounds like '<T extends A & B>'?

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

Which statement about generic type parameters is TRUE?

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

Which of the following is a valid generic method declaration in Java?

What is the primary purpose of bounded type parameters in generics?

Consider the declaration: List<? super Integer> list. What does this wildcard represent?