Interview Questions on Multithreading in Java With Answers

Multithreading in Java allows for multiple threads of execution within a Java program. This offers several advantages, including improved performance and smoother program flow. Multithreaded applications are becoming increasingly popular as they offer benefits such as reduced contention for resources, improved efficiency, and reduced complexity. This article will discuss Interview Questions on Multithreading in Java with Answers. Here are 30 Interview Questions on Multithreading in Java With Answers:

Table of Contents

Question 01: What is Multithreading in Java?

Answers: Multithreading is a Java feature that permits concurrent redaction of two or more parts of a program for high CPU utilization. Every part of such a program is called a thread. So, multithreading is a specialized form of multitasking.

Question 02: Why multithreading is used in Java?

Answers: Multithreading is used in Java to execute multiple threads simultaneously. This can be useful for tasks divided into smaller sub-tasks executed in parallel, such as image processing or video encoding.

Question 03: What are the benefits of multithreading?

Answers: Multithreading can provide numerous benefits to both the system and the programmer. Some benefits of multithreading include: 

  • Increased system throughput: By having multiple threads running simultaneously, the system’s overall throughput can be increased.
  • Increased responsiveness: Threads can provide a responsive user interface even while other tasks are running in the background. 
  • More efficient use of resources: Threads can be created and destroyed as needed, resulting in more efficient use of resources than a process-based approach.
  • More accessible to the program: Multithreading can make the programming of certain types of applications much more straightforward.
  • Greater flexibility: Multithreading can allow for greater flexibility in the design of an application.
  • Better performance: In some cases, multithreading can lead to better performance due to increased parallelism.
  • More robust applications: Multithreading can make applications more robust by providing a mechanism for error handling and recovery.
  • Enhanced security: Multithreading can provide enhanced security by isolating different threads from each other.
  • Improved debugging and testing: Multithreading can improve the debugging and testing of applications by allowing different threads to be monitored and tested independently.
  • Increased portability: Multithreading can increase the portability of applications by allowing them to be designed in a platform-independent manner.

Question 04: What is the difference between Process and Thread?

Answers: A process is an instance of a computer program being executed. A thread is a unit of execution within a step.

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Question 05: What are the types of multithreading?

Answers: The two most common types of multithreading are concurrent and parallel. Multithreading is a process of threads running in parallel, each taking its turn. This can allow multiple programs to run simultaneously, offering significant performance benefits. In addition, it is possible to run multiple programs on the same computer using multiple CPUs or GPUs in today’s technology.

Question 06: Why do we need multithreading in Java?

Answers: Multithreading in Java is used to allow multiple tasks to run simultaneously. This can be helpful for things like animation or running multiple processes simultaneously.

Question 07: What are the methods of multithreading in Java?

Answers: Multithreading in Java can be done in huge various ways, but the most general way is using threads. A thread is a sequence of instructions that are run together. Each instruction in a thread can do different things, making it possible to run multiple processes simultaneously.

The methods of multithreading in Java are:

  • Public void start(): It starts a new thread.
  • public void run(): It is used to execute the code inside the thread.
  • Public void stop(): It stops the thread’s execution.
  • Public void suspends (): It is used to suspend the thread’s execution.
  • Public void resume(): It is used to resume the thread’s execution. 
  • Public void yield(): It lets the other threads have a chance to execute.
  • Public void join(): It is used to wait for the thread to finish its execution. 
  • Public void setPriority(): It sets the thread’s priority.

Question 08: What is the challenge of Multithreading in Java?

Answers: The challenge of multithreading in Java is that it can be difficult to know when to use it and how to take advantage of its benefits properly. Additionally, multithreading can introduce potential concurrency issues that must be carefully managed to avoid race conditions and other unexpected behaviors.

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Question 09: How can we avoid deadlock in multithreading?

Answers: Deadlock is a common problem in multithreading applications. When two or more threads are working on the same task, they can’t continue because they don’t have enough time to finish. This can lead to a loss of performance or even an application crash. To prevent deadlock, you can use multiple workers and limit the number of tasks each can work on.

There are four main ways to avoid deadlock in multithreading: 

  • Avoid holding multiple locks at the same time.
  • Use lock order to prevent potential deadlocks.
  • Use tryLock() instead of lock() to avoid blocking.
  • Use a lock manager to keep track of locks and avoid deadlocks.

Question 10: Is Multithreading in Java necessary?

Answers: No, multithreading in Java is not necessary. However, it can be constructive in certain situations where you must perform multiple tasks simultaneously.

Question 11: Can Java threads run in parallel?

Answers: Yes, Java threads can run in parallel. Java is a highly powerful language that allows you to create parallelized applications. By using Java threads, you can schedule tasks on different processors and run them in parallel. This makes your code more efficient and less prone to errors.

Question 12: Where is multithreading used?

Answers: Multithreading is used in computer programming to allow multiple threads to exist within the context of a single process. These threads share the process’s resources but can execute independently.

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Question 13: What are the limitations of multithreading in Java?

Answers: Multithreading in Java is limited to a certain number of tasks that can be run at the same time. The programmer or the system can set this number. There are a few limitations of multithreading in Java: 

  • Starvation and deadlock are possible if the threads are not properly managed.
  • Context switching can lead to performance issues.
  • Not all tasks are suitable for multithreading.

Question 14: What are the principles of multithreading?

Answers: Multithreading is a process of running multiple threads concurrently in a single process. A thread is the smallest unit of execution within a process. Multithreading enables the process to have multiple execution flows.

Question 15: How many threads can be executed at a time?

Answers: The number of threads that can be executed simultaneously depends on the number of processors available.

Question 16: Is Java multithreaded by default?

Answers: No, Java is not multithreaded by default. Java was initially created as a platform-agnostic language that can run in multiple threads. However, recent versions of Java, such as Java SE 7 and Java SE 8, support multithreaded programming. This enables code to run in multiple threads, increasing performance and efficiency. Multithreaded programming is becoming more popular as more developers move towards developing web applications and mobile applications.

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Question 17: What is thread priority in Java?

Answers: Thread priority is an integer value that determines the order in which threads are scheduled for execution. The scheduler attempts to schedule higher priority threads before lower priority threads but will ultimately schedule all threads based on their priority relative to other threads with the same priority.

Question 18: What is thread synchronization in Java?

Answers: Thread synchronization is a mechanism that allows one thread to pause execution until another thread reaches a specific state.

Question 19: Which Kind of Multitasking is Better and Why?

Answers: Multitasking is an essential skill that many people take for granted. However, a few different types of multitasking can be better for different tasks. One type of multitasking is task switching. This type of multitasking allows you to switch between two or more tasks without leaving the current task. Another type of multitasking is split-tasking. Some people may find that they can focus better when they multitask, while others may find that they are more productive when focusing on one task at a time. Ultimately, it is up to the individual to experiment with different types of multitasking and find what works best for them.

Question 20: What are the Different Types of Threads in Java?

Answers: Threads are a popular way to manage multiple tasks in Java. They can be used to run multiple tasks on a single machine or to run multiple tasks on different machines. Threads can also be used to alleviate the amount of time required to perform a work. There are four different types of threads in Java: 

  • User-level threads: These are created and managed by the user. 
  • Kernel-level threads: These are created and managed by the operating system.
  • Hybrid threads are threads created and managed by both the user and the operating system.
  • Green threads: These are created and managed by the Java Virtual Machine (JVM).

Question 21: What is thread priority? [ Interview Questions on Multithreading in Java ]

Answers: Thread priority is a value the operating system uses to determine the order in which threads are scheduled for execution.

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Question 22: How does deadlock play an essential role in multithreading?

Answers: A deadlock is a situation where two or more threads are blocked forever, waiting for each other.

Question 23: What is Daemon Thread in Java, and explain their properties?

Answers: A daemon thread is a great service provider thread that provides services to the user thread. Its life actually depends on the user threads. When all the user threads die, the JVM terminates this thread automatically. The daemon thread does not prevent the JVM from terminating. 

Example: java.lang.Thread t = new Thread(); t.setDaemon(true);

Question 24: What are the benefits of multithreaded programming?

Answers: Multithreaded programming can offer many benefits, including the ability to more efficiently utilize multiple cores of a processor, improved responsiveness to input/output events, and more efficient use of system resources.

Question 25: What is the thread?

Answers: The thread is a fundamental part of the internet and has been around since the early days of the web. It is a way for users to communicate with each other and share ideas. The thread can be found on various websites, such as message boards and Reddit, and is used to discuss a wide range of topics.

Question 26: What is context switching?

Answers: In computer science, context switching is storing and retrieving the state (context) of a process or thread so that execution can be resumed from the same point later. This enables multiple processes or threads to share a single CPU or another resource.

Question 27: Describe the purpose and working of the sleep method.

Answers: The sleep method makes the currently executing thread go to sleep for a specified time. The time is given in milliseconds. After the time is up, the thread will be awake and ready to run again.

Question 28: What is a shutdown hook?- Interview Questions on Multithreading in Java

Answers: A shutdown hook is a thread that runs automatically when the JVM is shutting down. A shutdown hook is a function in a software application that triggers when the system enters a shutdown state. For example, this can be caused by a power failure, system crash, or user action. In addition, the shutdown hook can determine whether the system should be restarted or terminated.

Question 29: What is the Atomic action in Concurrency in Java?

Answers: Atomic actions are those actions that are indivisible and cannot be interrupted. That means once an atomic action is started, it will be executed entirely or not executed at all.

Question 30: What is Thread Scheduler in Java?

Answers: The thread scheduler is a part of the JVM that decides which thread should run. Thread Scheduler is a Java library that helps schedule tasks for execution in ascending or descending order. It is used in combination with JVM threads and the Java monitor.

Conclusion about Interview Questions on Multithreading in Java

It is essential to be aware of the different threading types in Java to create code that performs optimally. Additionally, it is beneficial to read through the various threading feature articles before starting work on a project. Finally, remember that it is best to use appropriate threading libraries when working with Thread Pool Executor, as they may provide better performance than the ones provided by Java. Thanks for reading this article about Interview Questions on Multithreading in Java and answers.