Java Notes

MULTI THREADING IN JAVA


🌟 What is Multithreading in Java?
Multithreading in Java is a process of executing multiple threads
simultaneously. A thread is the smallest unit of execution in a program.

Multithreading allows:

 Efficient CPU utilization.
 Better performance for programs with multiple tasks.
 Parallel execution of code.



🔁 Difference Between Process and Thread
Feature Process Thread
Definition An independent program A smaller unit of a process

Memory Each process has its own memory Shares memory with other threads

Communic-
Complex Easy (since memory is shared)
-ation
Overhead More Less

Example Chrome, Word Tabs in Chrome, background tasks

, 🧵 Life Cycle of a Thread
Java threads go through five stages:

Stage Description
New Thread is created using a constructor
Runnable Thread is ready to run but waiting for CPU
Running Thread is executing
Blocked Thread is waiting to acquire a lock
Terminated Thread has finished execution or has been stopped

(Image for reference only)


🛠️Creating Threads in Java
Java provides two main ways to create threads:

1. By extending the Thread class
java
CopyEdit
class MyThread extends Thread {
public void run() {
System.out.println("Thread running...");
}

public static void main(String[] args) {
MyThread t1 = new MyThread();
t1.start(); // starts the thread
}
}

2. By implementing the Runnable interface
java
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class MyRunnable implements Runnable {
public void run() {
System.out.println("Runnable thread running...");
}

public static void main(String[] args) {
Thread t = new Thread(new MyRunnable());
t.start();
}
}