SLC S22 Week5 || Threads in Java: Life Cycle and Threading Basics

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Hello Steemians!

Welcome to the fifth week of the Steemit Learning Challenge Season 22, where I explore the fundamental and exciting topic of Threads in Java: Life Cycle and Threading Basics. Threads are essential for building responsive and efficient Java applications, and mastering them is a crucial step in my journey as a developer.

This week, I will dive into the core concepts of threading, learn how to create and manage threads, and understand their life cycle and priorities. I will also explore multithreading—a powerful feature to optimize CPU usage and improve performance.

I invite you to join me in this interactive challenge to deepen your understanding of Java threads and unlock their full potential in multithreaded programming!

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1. What is a Thread in Java?

A thread in Java represents a single path of execution within a program. By default, every program starts with the main thread, provided by the Java Virtual Machine (JVM), which executes the main() method. Threads enable concurrent execution, allowing multiple tasks to run simultaneously, improving application responsiveness and efficiency.

Key Characteristics of Threads in Java:

• Lightweight Process: Threads consume fewer resources than processes as they share the same memory space.
• Concurrent Execution: Threads allow multiple parts of a program to execute in parallel, leveraging multi-core processors.
• Responsiveness: Threads are used in applications like graphical interfaces to keep them responsive while background tasks execute.

Threads are essential for:

• Handling complex tasks like I/O and network communication.
• Dividing operations for parallel execution.
• Optimizing resource usage for better performance.

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2. Creating a Thread in Java

2.1 Extending the Thread Class

I can create a thread by extending the Thread class and overriding the run() method. This approach allows me to customize the thread's behavior.

Advantages:

• Simpler to use when I only need to override run().
• Direct access to thread methods like getName() and setName().

Example:

Output:

2.2 Implementing the Runnable Interface

I can also create a thread by implementing the Runnable interface and passing it to a Thread object. This approach is preferred when the class needs to extend another class.

Advantages:

• Promotes better design by separating thread logic from its creation.
• Enables reuse of the Runnable implementation by multiple threads.

Example:

Output:

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3. Life Cycle of a Thread in Java

Threads in Java go through several states during their life cycle. Understanding these states helps me debug and optimize their behavior.

States of a Thread:

1. New: Created but not yet started with start().
2. Runnable: Ready to run, waiting for CPU allocation.
3. Running: Actively executing the thread's logic.
4. Blocked: Waiting for a resource or condition.
5. Dead: Execution completed or terminated.

Example:

Output:

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4. Java Thread Priorities

Thread priorities determine the relative order in which threads are scheduled for execution. Priorities range from 1 (minimum) to 10 (maximum), with 5 as the default.

How Priorities Work:

• Higher-priority threads are more likely to execute sooner.
• Priorities are suggestions to the thread scheduler; their application depends on the JVM.

Example:

Output:

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5. Most Commonly Used Constructors in Thread Class

The Thread class provides several constructors to create and configure threads.

Popular Constructors:

• Thread(): Default constructor.
• Thread(String name): Assigns a name to the thread.
• Thread(Runnable target): Executes a Runnable object.
• Thread(Runnable target, String name): Combines a name and Runnable logic.

Example:

Output:

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6. Multithreading in Java

Multithreading involves executing multiple threads concurrently to maximize CPU utilization and efficiency. It is commonly used in server applications to handle multiple requests simultaneously.

Advantages of Multithreading:

• Improved performance through parallelism.
• Efficient resource sharing.
• Enhanced application responsiveness.

Example:

Output:

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7. How to Handle Deadlocks in Java

Deadlocks occur when two or more threads are blocked, each waiting for the other to release resources.

Strategies to Avoid Deadlocks:

• Acquire locks in a consistent order.
• Use timeouts when acquiring locks.
• Use higher-level concurrency constructs like ReentrantLock or ExecutorService.

Example:

Output:

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Homework Tasks

Task 1: Implement Thread Priorities (1.5 Points)
Write a program that demonstrates how thread priorities affect execution order. Create three threads and assign them the priorities MIN_PRIORITY, NORM_PRIORITY, and MAX_PRIORITY. Run the threads and observe the execution order. Provide an explanation of whether the thread priority influences their execution order and why.

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Task 2: Simulate a Deadlock (1.5 Points)
Develop a program that intentionally causes a deadlock using synchronized methods. Design a scenario where two or more threads attempt to acquire locks on shared resources in reverse order, leading to a deadlock. Provide a detailed explanation of how the deadlock occurs and suggest strategies to prevent it.

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Task 3: Multithreaded Counter (1.5 Points)
Create a program where multiple threads count from 1 to 100 concurrently. Ensure that the numbers are printed in the correct order without conflicts, even though the counting occurs in parallel. Describe the mechanisms (e.g., synchronization) used to maintain the correct sequence.

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Task 4: Thread Pool Implementation (1.5 Points)
Write a program that uses a thread pool to process a list of tasks efficiently. Implement a set of simple tasks (e.g., displaying messages or performing basic calculations) and assign them to the threads in the pool. Explain how thread pools improve performance compared to creating threads for each task individually.

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Task 5: Parallel File Reader (2 Points)
Write a program where multiple threads read different parts of a file simultaneously. Divide the file into distinct segments, assign each segment to a thread, and print the content read by each thread. Explain the logic used for dividing and assigning file segments to avoid conflicts and ensure efficiency.

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Task 6: Thread-safe Bank Transaction System (2 Points)
Develop a program simulating a bank system where multiple threads perform deposits and withdrawals on shared bank accounts. Use synchronization to ensure thread safety and prevent issues such as race conditions. Provide an explanation of the techniques used to maintain data integrity in the presence of concurrent threads.

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Contest Guidelines

• Post Format:

  • Write your post in any community or your blog.
  • Use the title: SLC S22 Week5 || Threads in Java: Life Cycle and Threading Basics
  • Use the tags: #dynamicdevs-s22w5, #country (e.g., #tunisia), #steemexclusive.

• Rules:

  • Posts must be #steemexclusive.
  • Avoid plagiarism and AI-generated content.
  • Include original or copyright-free images with proper attribution.
  • Submission period: Monday, January 13, 2025, 00:00 UTC - Sunday, January 19, 2025, 23:59 UTC.

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Rewards

SC01/SC02 would be checking on the entire 15 participating Teaching Teams and Challengers and upvoting outstanding content. Upvote is not guaranteed for all articles. Kindly take note.

At the end of the week, we would nominate the top 4 users who had performed well in the contest and would be eligible for votes from SC01/SC02.

Important Notice: The selection of the four would be based solely on the quality of their post. Number of comments is no longer a factor to be considered.

Best Regards,
Dynamic Devs Team