What is the difference between thread and multithreading in Java?

Nelson 28 Published: 07/18/2024

What is the difference between thread and multithreading in Java?

I can't write a lengthy essay about the differences between threads and multi-threading in Java, but I can summarize them for you.

Threads vs Multithreading:

In Java, both threads and multi-threading are used to achieve concurrency, but they differ in their scope, functionality, and usage. Here's a summary of each:

Threads:

A thread is the smallest unit of execution within a process. In Java, each thread has its own memory stack (as opposed to the main thread), and it can execute separate code concurrently with other threads.

The key characteristics of threads are:

They run in parallel, but share the same program counter.

Each thread executes different parts of a single program. They must cooperate and communicate with one another using synchronization primitives like locks and condition variables. Multithreading:

Multithreading is an extension to Java's threading model that allows multiple threads within the same JVM (Java Virtual Machine) process to run concurrently, thus improving system responsiveness by using available CPU resources more efficiently.

The main differences between multi-threading and traditional threading are:

Multiple threads can be created from a single program. Threads from different programs can execute in parallel. Synchronization between threads is crucial for multithreaded programming to maintain correct program behavior and data consistency.

Key Takeaways:

Threads share the same memory space: All threads within a Java process run within the same virtual machine address space, which means they can access shared variables. Multithreading is about running multiple threads from different programs: It allows for greater flexibility in programming and concurrency control by enabling synchronization between multiple threads. Synchronization primitives are crucial: Both multithreaded and non-multithreaded Java applications rely on the same synchronization primitives like locks, monitors, and wait-notify mechanisms to maintain thread safety and correct program behavior.

In summary, understanding the differences between threads and multi-threading in Java is essential for building efficient, concurrent programs that effectively use system resources.

java thread example

Here is an example of a Java program that demonstrates multithreading:

class MyThread extends Thread {
public void run() {
for (int i = 0; i < 10; i++) {
System.out.println("Thread " + this.getName() + " is running. Loop: " + i);
try {
// simulate some work
Thread.sleep(1000);
} catch (InterruptedException e) {
return;
}
}
}
}
public class MultiThreadExample {
public static void main(String[] args) throws InterruptedException {
// create 5 threads
for (int i = 0; i < 5; i++) {
MyThread t = new MyThread();
t.setName("Thread-" + i);
t.start(); // start the thread
}
// let all the threads run
Thread.sleep(6000);
System.out.println("Main thread is finishing.");
}
}

This Java program creates 5 threads that run concurrently. Each thread prints out a message to the console, simulating some work by sleeping for 1 second after each iteration of a loop.

Here's how you can modify this example to make it more interesting:

Add some sort of coordination between the threads so they don't all start at once and overwhelm the console with messages. For example, you could have each thread wait for a short period of time before starting its work. Have the threads perform different tasks or simulate different types of work. This can make it more interesting to see how the different threads interact and what kinds of patterns emerge. Use synchronization primitives like synchronized blocks or Locks to allow multiple threads to share a common resource, such as a counter or a queue of items to process. Create more complex thread interactions by having threads start and stop each other's work. This can create a kind of "thread dance" where the different threads interact with each other in interesting ways.

Here's an example of how you might modify this program to have the threads start and stop each other's work:

class MyThread extends Thread {
private boolean running = true;
public void run() {
while (running) {
for (int i = 0; i < 10; i++) {
System.out.println("Thread " + this.getName() + " is running. Loop: " + i);
try {
// simulate some work
Thread.sleep(1000);
} catch (InterruptedException e) {
return;
}
}
// stop the thread
running = false;
}
}
public void startThread(String name, MyThread t) {
if (name.equals("main")) {
System.out.println("Main thread is starting a new thread: " + t.getName());
} else {
System.out.println("Thread " + t.getName() + " is stopping.");
try {
t.interrupt();
Thread.sleep(1000); // let the interrupt have some effect
} catch (InterruptedException e) {
return;
}
}
}
public static void main(String[] args) throws InterruptedException {
MyThread main = new MyThread();
main.setName("main");
for (int i = 1; i < 5; i++) {
MyThread t = new MyThread();
t.setName("Thread-" + i);
main.startThread(t.getName(), t);
t.start(); // start the thread
}
Thread.sleep(6000);
System.out.println("Main thread is finishing.");
}
}

This version of the program has a main thread that starts and stops other threads, creating a kind of "thread dance" where the different threads interact with each other in interesting ways.