Java Programming - MCQ Practice Questions

What output will this produce? java List<? super Integer> list = new ArrayList<Number>(); list.add(5); Integer val = (Integer) list.get(0);

Which Java feature was introduced specifically to support generics compilation?

A method processes collections where items need to be added back to the same collection type. Which wildcard approach ensures type safety for write operations?

What will be the output of this nested lambda? Function<Integer, Function<Integer, Integer>> add = x -> y -> x + y; System.out.println(add.apply(3).apply(5));

What will happen if you try to compile this code? BiFunction<String, String, String> concat = (a, b) -> a + b; concat.apply("Java", "8", "Features");

What is the type inference mechanism in lambda expressions?

Consider a lambda that needs to throw a checked exception. Which approach is correct?

What is the time complexity of reducing a stream with a lambda expression using reduce()?

Consider: List<String> list = Arrays.asList("a", "b", "c"); list.stream().collect(Collectors.toMap(s -> s, s -> s.length())). What type is returned?

What issue can arise when using lambda expressions with flatMap() in nested streams?

Consider: Function<Integer, Function<Integer, Integer>> curry = x -> y -> x + y; What does curry.apply(5).apply(3) return?

What is the time complexity of reducing a stream with a stateful lambda operation?

Consider: Function<Integer, Function<Integer, Integer>> curried = a -> b -> a + b; What is this pattern called?

Consider: Stream.of(1, 2, 3).map(x -> { System.out.println(x); return x * 2; }).collect(Collectors.toList()); What will print?

What is the correct way to chain lambda expressions using Function interface? Function<Integer, Integer> f1 = x -> x * 2; Function<Integer, Integer> f2 = x -> x + 5; How to apply f1 first, then f2?

Consider a scenario where you need to sort a list of strings by length. Which lambda expression is most appropriate for Comparator?

What is the difference between a lambda expression and an anonymous inner class in Java?

In the context of exception handling with lambda expressions, what happens if a lambda body throws a checked exception?

Which of the following best demonstrates the use of Optional with lambda expressions for safe null handling?

What is the return type of a lambda expression used with IntStream.range(1, 5).map(x -> x * 2)?