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Notify.java
Notify.java
 
 
NotifyAll.java
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Wait.java
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readme.md
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readme.md

☕ Java Lesson – Thread Communication in Java

Is lesson me hum seekhenge:

  • Thread Communication kya hota hai
  • wait(), notify(), notifyAll()
  • Producer-Consumer problem
  • Important rules aur examples

1️⃣ Thread Communication Kya Hota Hai?

Thread communication ka matlab:

multiple threads ka ek dusre ke saath coordinate karna

Example:

ek thread wait kare jab tak dusra kaam complete na kare

2️⃣ Problem – Without Communication

Agar threads coordinate na kare:

data inconsistency ya wrong execution ho sakta hai

3️⃣ Important Methods

Java me communication ke liye 3 methods:

wait()
notify()
notifyAll()

Ye methods:

Object class ke hote hain

4️⃣ wait() Method

thread ko wait state me bhej deta hai

wait();

✔ lock release karta hai
✔ dusra thread ka wait karta hai

5️⃣ notify() Method

ek waiting thread ko jagata hai

notify();

6️⃣ notifyAll() Method

sab waiting threads ko jagata hai

notifyAll();

7️⃣ Important Rule ⚠

✔ wait(), notify(), notifyAll() sirf:

synchronized block ya method ke andar use hote hain

8️⃣ Producer-Consumer Problem

Real example:

Producer → data banata hai  
Consumer → data use karta hai

9️⃣ Example – Thread Communication

class Shared {

    int data;
    boolean available = false;

    synchronized void produce(int value) throws Exception {

        if(available){
            wait();
        }

        data = value;
        available = true;

        System.out.println("Produced: " + data);

        notify();
    }

    synchronized void consume() throws Exception {

        if(!available){
            wait();
        }

        System.out.println("Consumed: " + data);

        available = false;

        notify();
    }
}

🔟 Main Class

class Test {

    public static void main(String[] args){

        Shared s = new Shared();

        Thread producer = new Thread(() -> {
            try {
                for(int i = 1; i <= 5; i++){
                    s.produce(i);
                }
            } catch(Exception e){}
        });

        Thread consumer = new Thread(() -> {
            try {
                for(int i = 1; i <= 5; i++){
                    s.consume();
                }
            } catch(Exception e){}
        });

        producer.start();
        consumer.start();
    }
}

1️⃣1️⃣ Flow

Producer produce karega → notify  
Consumer consume karega → notify

1️⃣2️⃣ Real-Life Analogy

Restaurant:
Chef (producer) → food banata hai  
Customer (consumer) → food khata hai

1️⃣3️⃣ Important Points

✔ wait() lock release karta hai
✔ notify() ek thread ko jagata hai
✔ notifyAll() sabko jagata hai
✔ synchronized required hai

1️⃣4️⃣ Common Mistakes

❌ wait() outside synchronized
❌ notify() without condition check

🎯 Interview Questions

  1. Thread communication kya hota hai?
  2. wait() aur sleep() me difference?
  3. notify() vs notifyAll()?
  4. Producer-Consumer problem kya hai?

🧾 Lesson Summary

Is lesson me humne seekha:

✔ Thread communication concept
✔ wait(), notify(), notifyAll()
✔ Producer-Consumer example
✔ synchronization rules

Thread communication Java me threads ke beech coordination aur synchronization ke liye use hota hai.