Q 1. What is the difference between an array and a linked list?

 general, arrays are a good choice for data structures where thedata is accessed frequently and the order of the data is

important. Linked lists are a good choice for data structures where the data is inserted or deleted frequently and the order of the data is not

important

Q 2. Explain the concept of a hash table.

put(key, value): This method stores the key-value pair in the hash table.

get(key): This method returns the value associated with the key.

remove(key): This method removes the key-value pair from the hash table.

Q 3. What is the time complexity of various operations in a binary search tree (BST)?

The time complexity of various operations in a binary search tree (BST) depends on the height of the tree. The height of a BST is the number of nodes on the longest path from the root node to a leaf node

Q 5. Explain the concept of a priority queue and provide an example of its application

A priority queue is a data structure that stores elements along with their associated priorities. It allows efficient retrieval of the element with the highest (or lowest) priority. The priority determines the order in which elements are processed or
accessed.

Q 6. Explain the concept of dynamic programming and provide an example problem where it can be applied.

Dynamic programming is a problem-solving technique that involves breaking down complex problems into smaller, overlapping subproblems and solving them in a bottom-up manner.

Q 7. How does a HashSet work internally in Java?

A HashSet internally uses a HashMap to store its elements. When  you add an element to a HashSet, it is first hashed using the

hashCode() method.

The hash code is then used to find the corresponding bucket in the HashMap. If the bucket is empty, the element is added to the bucket. If the bucket is not empty, the element is compared to

the other elements in the bucket using the equals() method. If the element is equal to any of the other elements in the bucket, it is

not added to the HashSet.

Q 8. What is the time complexity of various operations in a hash table?

The time complexity of various operations in a hash table depends on the hash function used and the number of elements nin the hash table. In general, the time complexity of the following

operations is:

Insertion: O(1) on average, O(n) in the worst case

Search: O(1) on average, O(n) in the worst case

Deletion: O(1) on average, O(n) in the worst case

multithreading

Q 1. What is multithreading, and why is it important in  Java?

Multithreading is a programming concept that allows multiplen tasks to be executed concurrently. In Java, multithreading is implemented using the Thread class. A Thread object represents

a single thread of execution.

Increased performance:

Improved responsiveness:

Reduced resource usage

Q 3. What is the difference between a process and a  thread?

Processes are independent of each otherProcesses are heavier than threads. Processes are more difficult to create and manage thannthreads.

A process is a program in execution. It has its own memory space, ts own stack, and its own set of resources.

A thread is a lightweight process that shares the same memory space and resources as other threads in the same proces

Q 4. How does synchronization work in Java? Explain the concepts of synchronized methods and blocks.

Using synchronized methods

Using synchronized blocks

Synchronization in Java is a mechanism that allows multiple threads to access shared resources safely. When a thread is synchronized on a resource, it is the only thread that can access

that resource.

This prevents race conditions, which are situations where two or more threads are trying to access the same resource at the same

time. There are two ways to synchronize in Java

Q 5. What is a deadlock, and how can it be avoided?

A deadlock is a situation where two or more threads are waiting for each other to finish. This can happen when two threads are each trying to acquire a lock on the same resource.

Avoid using locks unnecessarily.

Use locks in a consistent order.

Use deadlock detection and prevention tools

Q 6. What are the differences between the Thread class and the Runnable interface in Java?

The Thread class is a concrete class. while the Runnable interface is an abstract interface. This means that you can create a new thread by extending the Thread class, or you can create a new

thread by implementing the Runnable interface.

Q 7. What is the purpose of the volatile keyword in Java?

The volatile keyword is used to ensure that all threads see the same value of a variable, even if the value is changed by another

thread

Q 8. Explain the difference between preemptive scheduling and time-slicing in the context of thread scheduling..

Preemptive scheduling is when the operating system can forcibly remove a thread from the CPU and give it to another thread. Time-slicing is when each thread is given a certain amount of time

to run on the CPU.

The main difference is that in preemptive scheduling, the operating system can interrupt a thread at any time, while in time-slicing, the thread is only interrupted when it has used up its

allotted time.

Exception Handling

Q 1. What is an exception in Java, and why is exception  handling important?

In Java, an exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions. It is an

object which is thrown at runtime.

Q 2. How does Java handle exceptions.

java handles exceptions by using a mechanism called exception propagation. When an exception is thrown, it is propagated up jthe call stack until it is caught. If the exception is not caught, the

program will crash

Q 3. Describe the try-catch-finally block and its purpose in exception handling.

The try-catch-finally block is a Java syntax that allows you to handle exceptions gracefully. It consists of three parts:

The try block

The catch block

The finally block

Prevents program crashes

Allows you to recover from errors

Provides information about the error

Makes your code more robust

Makes your code easier to read and understand

Q 4. What is the difference between the throw and throws keywords in Java?

The throw keyword is used to explicitly throw an exception

The throws keyword is used to declare that a method can throw an exception.

Q 5. How can you create custom in java?

To create a custom exception in Java, you need to create a class  that extends the Exception class. The custom exception class can

have its own constructors, methods, and fields.