Java Programming

Java MCQ: Arrays in Java are? a) Objects b) Primitive data types c) Methods d) None of the above Answer: a) Objects Explanation: In Java, arrays are considered objects. This means they are instances of a class, and they have a built-in field length that stores their size. Reference links: https://www.rameshfadatare.com/learn-java-programming/ https://www.javaguides.net/p/java-tutorial-learn-java-programming.html

Java MCQ: Select the valid statement to declare and initialize an array. a) int[] arr = new int[5]; b) int arr[] = new int[5]; c) int arr[] = {1, 2, 3, 4, 5}; d) All of the above Answer: d) All of the above Explanation: All the provided statements are valid ways to declare and

Java MCQ: When an array is passed to a method, what does the method receive? a) The reference of the array b) A copy of the array c) Length of the array d) Copy of the first element Answer: a) The reference of the array Explanation: When an array is passed to a method in

Java MCQ: Automatic type conversion is possible in which of the possible cases? a) When the source type is larger than the destination type b) When the source type is smaller than the destination type c) When the types are incompatible d) None of the above Answer: b) When the source type is smaller than

Java MCQ: What is the size of float and double in Java? a) 32 and 64 b) 32 and 32 c) 64 and 64 d) 64 and 32 Answer: a) 32 and 64 Explanation: In Java, a float is a 32-bit IEEE 754 floating-point, and a double is a 64-bit IEEE 754 floating-point. Float has

Java MCQ: Number of primitive data types in Java are? a) 6 b) 7 c) 8 d) 9 Answer: c) 8 Explanation: Java has 8 primitive data types: byte, short, int, long, float, double, char, and boolean. These data types serve as the building blocks for data manipulation in Java. Reference links: https://www.rameshfadatare.com/learn-java-programming/ https://www.javaguides.net/p/java-tutorial-learn-java-programming.html

Java MCQ: Which of the following is true about the LinkedHashMap class? a) It maintains insertion order b) It is a subclass of HashMap c) It allows null values d) All of the above Answer: d) All of the above Explanation: The LinkedHashMap class in Java maintains the insertion order of elements, is a subclass

Java MCQ: Which interface does PriorityQueue implement in Java? a) Queue b) List c) Set d) Map Answer: a) Queue Explanation: The PriorityQueue class in Java implements the Queue interface. It provides a way to order elements based on their priority and is part of the Java Collections Framework. Understanding the Queue interface and its

Java MCQ: What is the main difference between HashMap and Hashtable? a) HashMap is unsynchronized, Hashtable is synchronized b) HashMap allows null keys and values, Hashtable does not c) HashMap is generally faster than Hashtable d) All of the above Answer: d) All of the above Explanation: The main differences between HashMap and Hashtable are:

Java MCQ: What is a PriorityQueue in Java? a) A queue that orders elements based on their priority b) A queue that stores elements in a first-in, first-out order c) A queue that does not allow duplicates d) A queue that maintains insertion order Answer: a) A queue that orders elements based on their priority

Java MCQ: What is a Hashtable in Java? a) A synchronized map that does not allow null keys or values b) A map that maintains insertion order c) A map that allows null values d) A map that stores keys in a sorted order Answer: a) A synchronized map that does not allow null keys

Java MCQ: What is a TreeMap in Java? a) A map that stores keys in a sorted order b) A map that allows null keys c) A map that does not allow duplicate keys d) A map that uses a linked list internally Answer: a) A map that stores keys in a sorted order Explanation:

Java MCQ: What is a LinkedHashMap in Java? a) A map that maintains the insertion order of its elements b) A map that sorts keys in natural order c) A map that does not allow null values d) A map that allows duplicate keys Answer: a) A map that maintains the insertion order of its

Java MCQ: What is a HashMap in Java? a) A map that stores key-value pairs with unique keys and allows null values b) A map that stores keys in a sorted order c) A map that does not allow null keys or values d) A list that allows duplicates Answer: a) A map that stores

Java MCQ: What is the Map interface in Java? a) A collection that maps keys to values b) A collection that stores elements in a sequence c) A collection that does not allow null values d) A collection that allows duplicates Answer: a) A collection that maps keys to values Explanation: The Map interface in

Java MCQ: What is a TreeSet in Java? a) A set that stores elements in a sorted order b) A set that allows duplicates c) A set that stores key-value pairs d) A set that does not allow null elements Answer: a) A set that stores elements in a sorted order Explanation: A TreeSet in

Java MCQ: What is a LinkedHashSet in Java? a) A set that maintains insertion order b) A set that does not allow duplicates but is unordered c) A list that allows duplicates d) A map that stores key-value pairs Answer: a) A set that maintains insertion order Explanation: A LinkedHashSet in Java is a set

Java MCQ: What is a HashSet in Java? a) A collection that does not allow duplicates and is unordered b) A collection that maintains insertion order c) A collection that maps keys to values d) A collection that allows duplicates Answer: a) A collection that does not allow duplicates and is unordered Explanation: A HashSet

Java MCQ: What does the Set interface represent? a) A collection that does not allow duplicates b) A collection that allows null values c) A collection that maintains order d) A collection that maps keys to values Answer: a) A collection that does not allow duplicates Explanation: The Set interface in Java represents a collection

Java MCQ: What is a Vector in Java? a) A synchronized, dynamic array b) A type of linked list c) An unsynchronized array d) A set that does not allow duplicates Answer: a) A synchronized, dynamic array Explanation: A Vector in Java is a synchronized, dynamic array that can grow as needed. It allows elements

Java MCQ: What is a Stack in Java? a) A last-in, first-out (LIFO) data structure b) A first-in, first-out (FIFO) data structure c) A collection that does not allow duplicates d) A collection that maps keys to values Answer: a) A last-in, first-out (LIFO) data structure Explanation: A Stack in Java is a last-in, first-out

Java MCQ: What is the difference between ArrayList and LinkedList? a) ArrayList uses a dynamic array, LinkedList uses a doubly linked list b) ArrayList allows duplicates, LinkedList does not c) ArrayList is thread-safe, LinkedList is not d) ArrayList does not allow null elements, LinkedList does Answer: a) ArrayList uses a dynamic array, LinkedList uses a

Java MCQ: What is the List interface in Java? a) A collection that stores elements in an ordered sequence b) A collection that does not allow duplicates c) A collection that maps keys to values d) A collection that supports random access Answer: a) A collection that stores elements in an ordered sequence Explanation: The

Java MCQ: What does the Collection interface represent in Java? a) A group of objects b) A single object c) A database connection d) A multithreading mechanism Answer: a) A group of objects Explanation: The Collection interface in Java represents a group of objects, known as elements. It is the root interface of the Java

Java MCQ: What is the Java Collections Framework? a) A set of classes and interfaces for storing and manipulating groups of data b) A framework for managing database connections c) A framework for handling files d) A framework for multithreading Answer: a) A set of classes and interfaces for storing and manipulating groups of data