Java Interview Guide : 200+ Interview Questions and Answers - Collection Code Examples

The video tutorial provides an in-depth exploration of Java collections, covering various implementations such as ArrayList, HashSet, TreeSet, HashMap, and TreeMap. It explains operations like adding, removing, and sorting elements, and highlights the use of Comparable and Comparator interfaces for sorting. The tutorial also delves into the functionality of NavigableSet and NavigableMap, as well as the PriorityQueue with natural and custom ordering. Finally, it discusses static methods in the Collections class, offering practical examples and coding exercises to reinforce learning.

What happens when you add an element to an ArrayList without specifying an index?

• The element is not added.

• The element is added at the beginning of the list.

• The element is added at the end of the list.

• The element replaces the first element.

Which method would you use to check if an ArrayList contains a specific element?

• indexOf

• contains

• get

• add

What must a class implement to be sorted using Collections.sort()?

• Serializable

• Comparator

• Iterable

• Comparable

How can you sort a collection in descending order?

• Use Collections.reverseOrder()

• Use a custom Comparator

• Use Collections.sort() with a flag

• Use a custom Comparable

What is a key characteristic of a HashSet?

• It maintains elements in insertion order.

• It does not allow duplicate elements.

• It sorts elements in natural order.

• It allows duplicate elements.

In a TreeSet, how are elements stored?

• In insertion order

• In reverse order

• In random order

• In sorted order

What happens when you add a duplicate key to a HashMap?

• The new value replaces the old value.

• The key is ignored.

• An error is thrown.

• Both values are stored.

How does a TreeMap store its keys?

• In reverse order

• In sorted order

• In insertion order

• In random order

What is the default priority in a PriorityQueue?

• Numbers are stored in insertion order

• Smallest numbers have highest priority

• Numbers are stored in reverse order

• Largest numbers have highest priority

Which method in the Collections class can be used to reverse a list?

• reverseOrder

• reverse

• invert

• flip