Java - Multithreading - Hands-on

Learning Objectives

• Understand how to create and manage threads in Java.
• Implement different thread states and synchronization techniques.
• Apply multithreading to real-world scenarios.

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Exercise 1: Creating and Starting a Thread

Problem Statement

Write a program that creates and starts a thread by extending the Thread class.

Instructions:

1. Define a class that extends Thread.
2. Override the run() method to print a message.
3. Create an instance of the class and start the thread using start().

Expected Output:

• The thread should print a message indicating it is running.

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Exercise 2: Implementing Runnable Interface

Problem Statement

Create and start a thread using the Runnable interface.

Instructions:

1. Define a class that implements Runnable.
2. Implement the run() method to display a message.
3. Create a Thread object and pass the class instance to it.
4. Start the thread.

Expected Output:

• The thread should print a message indicating it is running.

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Exercise 3: Thread Synchronization

Problem Statement

Demonstrate thread synchronization using the synchronized keyword.

Instructions:

1. Create a class with a synchronized method.
2. Start multiple threads accessing the method.
3. Observe how synchronization prevents race conditions.

Expected Output:

• A well-ordered sequence of method execution without interference.

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Exercise 4: Thread Sleep and Join

Problem Statement

Use Thread.sleep() and join() to control thread execution timing.

Instructions:

1. Create a thread that prints messages with delays using sleep().
2. Start multiple threads and use join() to wait for one thread to finish before others continue.

Expected Output:

• Delayed messages printed sequentially.

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Exercise 5: Thread States

Problem Statement

Simulate different thread states: NEW, RUNNABLE, BLOCKED, WAITING, TIMED_WAITING, and TERMINATED.

Instructions:

1. Create a thread and print its state at various execution points.
2. Use sleep(), wait(), and join() to transition through different states.

Expected Output:

• Console output showing the thread transitioning through different states.

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Exercise 6: Copy Files Using Threads

Problem Statement

Write a program that copies files from one directory to another using multiple threads.

Instructions:

1. Accept source and destination directory paths as input.
2. List all files in the source directory.
3. Create multiple threads to copy files concurrently.

Expected Output:

• Files copied efficiently using multiple threads.

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🔗 Related Topics:

• Multithreading
• Thread Lifecycle
• Virtual Threads

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