Java multithreading Tutorial with Real-Life-Example(2025)

 

Java Multithreading Tutorial with Real-Life Examples (2025)

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Learn Java Multithreading with real-world examples. Understand thread lifecycle, synchronization, and interview questions. Perfect for beginners and job-seekers in 2025.

Introduction – Java Threading kya hota hai?

Aaj ke time mein har fast aur responsive application ke peeche ek powerful concept chhupa hota hai – Multithreading in Java.
Java mein threads allow karte hain ek se zyada kaam parallel chalane ka — jaise ek hi waqt pe file download bhi ho rahi ho aur user interface bhi active ho.

Agar tu Java developer banna chahta hai ya interviews crack karna chahta hai, toh threading ka concept samajhna zaroori hai.

1. What is Multithreading in Java?

Multithreading ka matlab hota hai ek hi program ke andar multiple threads run karna, jisse program fast aur efficient ban jata hai.

• Java ek multithreaded language hai.
• Har thread ek independent unit hoti hai jo parallel mein run karti hai.
• Example: Agar tu YouTube use karta hai – video chal rahi hoti hai, comments load ho rahe hote hain – all because of multithreading.

2. Thread Lifecycle in Java

Thread ke 5 main states hote hain:

1. New
2. Runnable
3. Running
4. Waiting/Blocked
5. Terminated

3. Java Thread kaise banaye?

(a) Thread class extend karke:

class MyThread extends Thread {
    public void run() {
        System.out.println("Thread chal raha hai...");
    }
}

public class Demo {
    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        t1.start();  // start() se hi thread chalu hota hai
    }
}

(b) Runnable interface implement karke:

class MyRunnable implements Runnable {
    public void run() {
        System.out.println("Runnable thread chal raha hai...");
    }
}

public class Demo {
    public static void main(String[] args) {
        Thread t1 = new Thread(new MyRunnable());
        t1.start();
    }
}

Note: Runnable zyada flexible aur scalable hota hai.

4. Thread Synchronization in Java

Multithreading ke saath problem aata hai — race condition. Jab 2 threads ek hi resource access karte hain bina control ke, toh problem hoti hai.

Solution: synchronized keyword

class Bank {
    synchronized void withdraw(int amount) {
        System.out.println("Withdrawing: " + amount);
        // some logic here
    }
}

5. Thread Pool in Java (ExecutorService)

Agar tu har baar naya thread banayega, toh memory use badhega.

Best Practice: Use thread pool

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Demo {
    public static void main(String[] args) {
        ExecutorService pool = Executors.newFixedThreadPool(3);

        pool.execute(() -> System.out.println("Thread 1 chal raha hai"));
        pool.execute(() -> System.out.println("Thread 2 chal raha hai"));
        pool.shutdown();
    }
}

6. Java Threading – Interview Questions

• What is the difference between start() and run()?
• What is synchronization in Java?
• What are daemon threads?
• How is Runnable different from Thread?
• What is the thread lifecycle?

7. Internal Linking Ideas:

• OOPs Concepts in Java
• Exception Handling in Java
• Java Collections Framework

Conclusion

Multithreading Java ka ek advanced topic hai jo har serious developer ko aana chahiye. Chahe tu beginner ho ya interview dene ja raha hai – threads, synchronization, aur executor service jaise concepts tere career mein help karenge.

Next Post: Java Exception Handling Explained

🔑 Keywords (Labels/Tags ke liye):

java multithreading, java thread example, thread lifecycle java, thread synchronization java, multithreading interview questions

 Java Inheritance Update 2023 With Program And Example 

nheritance is one of the essential concepts in object-orientated programming 

(OOP) that lets in you to create a new magnificence this is based on an current elegance. 

Inheritance allows you to define a brand new elegance (known as a subclass or derived magnificence) via inheriting 

The homes and behaviors (fields and strategies) of an existing class (called a superclass or base magnificence). 

This allows for code reuse and the introduction of a hierarchy of instructions.

Here's a simple Java program that demonstrates inheritance:

// Superclass (Base class)

class Animal {

    String name;

    Animal(String name) {

        this.name = name;

    }

    void eat() {

        System.out.println(name + " is eating.");

    }

    void sleep() {

        System.out.println(name + " is sleeping.");

    }

}

// Subclass (Derived class)

class Dog extends Animal {

    Dog(String name) {

        super(name); // Call the constructor of the superclass

    }

    void bark() {

        System.out.println(name + " is barking.");

    }

}

// Subclass (Derived class)

class Cat extends Animal {

    Cat(String name) {

        super(name); // Call the constructor of the superclass

    }

    void meow() {

        System.out.println(name + " is meowing.");

    }

}

public class InheritanceExample {

    public static void main(String[] args) {

        Dog dog = new Dog("Buddy");

        Cat cat = new Cat("Whiskers");

        dog.eat();

        dog.sleep();

        dog.bark();

        cat.eat();

        cat.sleep();

        cat.meow();

    }

}

In this program:

We define a Animal superclass with fields call and methods devour() and sleep().

We create  subclasses, dog and Cat, which inherit from the Animal superclass.

Both canine and Cat training have their constructors, and they name the constructor of 

The superclass using awesome(name) to initialize the call discipline.

Every subclass has extra strategies (bark() for canine and meow() 

For Cat) further to the inherited techniques.

Within the essential approach, we create instances of dog and Cat and show how inheritance 

Works by means of calling each inherited and subclass-unique methods.

That is a fundamental example of inheritance in Java, wherein subclasses inherit the houses 

And behaviors of the superclass, taking into consideration code reuse and 

Company of associated lessons in a hierarchy.

 A Basic Java Program For Beginners 2023

                 Static Nested Class

1) Static Nested ClassIn java static nested class is a class which is defined in a class with static keyword.

static nested class cannot access non-static data member and methods of outer class. It can access only static data member of outer class including private.

 Java Static Nested Class Example

class Simple

{

static int a = 700;

static class SimpleInner

{

void show()

{

System.out.println("value is"+a);

}

}

public static void main(String args[])

{

Simple.SimpleInner s = new Simple.SimpleInner();

s.show();

}

}

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Non-Static Nested Class(inner class)

*1) Member Inner Class* 

 

In java member inner class is a class which is defined in class but outside of a method is called member inner class.

*Java Member Inner Class Example* 

Java member inner class defined in a class but outside of method of that class.

In this example we will create outer class(MemberOuter) and inner class(MemberInner) and declare a private data member in outer class and access this private data member in inner class because inner class can access all the data members and methods in inner class, including private data member and methods.

class MemberOuter

{

private int salary = 4000;//private data member of outer class

class MemberInner

{

void get()

{

System.out.println("salary is "+salary);//access in inner class

}

}

public static void main(String args[])

{

MemberOuter mo = new MemberOuter();

MemberOuter.MemberInner mi = mo.new MemberInner();

mi.get();

}

} 

output : salary is 4000 

Note :

(1)  In case of java outer and inner class, Here the java compiler creates two .class files the first is MemberOuter.class and MemberOuter$MemberInner.class.

(2) If you want to instantiate inner class, you must have to create the instance of outer class and instance of inner class is created inside the instance of outer class.

*2) Anonymous Inner Class* 

In java anonymous inner class is a class that have no name is called anonymous inner class. This class can be instantiated only once. It is usually declared inside a method or block.

Anonymous inner class can be created by two ways in java 

Using class(abstract or concrete)

Using interface

*Java Anonymous Inner Class Example* 

 abstract class AIExample

{

abstract void show();

}

class Test

{

public static void main(String args[])

{

AIExample a = new AIExample()

{

void show()

{

System.out.println("Method of anonymous class");

}

};

a.show();

}

}

output : Method of anonymous class 

 

The above example is performing anonymous by using abstract class.

*Java Anonymous Inner Class Example - Using Interface* 

This is simple example of anonymous inner class using interface.

 

interface AnonymousExmple

{

void show();

}

 

class Test

{

public static void main(String args[])

{

AnonymousExmple ae = new AnonymousExmple()

{

public void show()

{

System.out.println("hello java ");

}

};

ae.show();

}

}

output : hello java

*3) Java Local Inner Class* 

In java local inner class is a class which is created inside a method is called local inner class in java. If you want to invokes the method of local inner class, you must instantiate this class inside the method.

*Java Local Inner Class Example* 

class LICExample

{

private int a = 40;

void show()

{

class LICExample1

{

void get()

{

System.out.println("value is "+a);

}

}

LICExample1 l = new LICExample1();

l.get();

}

public static void main(String args[])

{

LICExample ll = new LICExample();

ll.show();

}

}

output : value is 40

 Explain Collection Framework Hierarchy in Java 2022 Update. 

All the interfaces and classes for the collection framework are located in java.util package.

The basic interface of the collections framework is the Collection interface which is the root interface of all collections in the API and placed at the top of the collection hierarchy.Collection interface extends the Iterable interface. 

Collection Framework Hierarchy in Java core-java-interview-questions for freshers 

1. List

It handles sequential list of objects. ArrayList, Vector and LinkedList classes implement this interface.

2. Queue

It handles the special group of objects in which elements are removed only from the head. 
Linked List and Priority Queue classes implement this interface.

3. Set

It handles the group of objects which must contain only unique elements. 
This interface is implemented by HashSet and LinkedHashSet classes and extended by 
SortedSet interface which in turn, is implemented by TreeSet.

4. Map

This is the one interface in Collection Framework which is not inherited from Collection interface. 
It handles the group of objects as Key/Value pairs. It is implemented by 
HashMap and HashTable classes and extended by SortedMap interface which in turn is implemented by TreeMap.
Three of above interfaces (List, Queue and Set) inherit from Collection interface.
Although, Map is included in collection framework it does not inherit from Collection interface.

What are Major Features of java New Update Varsion 2022 ?

         Q: What are the major features of Java ?

             Answer:
             A list of most important features of Java language is given below

1. Simple

Java is easy to learn and its syntax is quite simple, clean and easy to understand. The confusing and ambiguous concepts of C++ are either left out in Java or they have been re-implemented in a cleaner way.
Eg : Pointers and Operator Overloading are not there in java but were an important part of C++.

2. Object Oriented

Java is an object-oriented programming language. Everything in Java is an object. Object-oriented means we organize our software as a combination of different types of objects that incorporates both data and behavior. Object-oriented programming (OOPs) is a methodology that simplifies software development and maintenance by providing some rules.

3. Robust

Robust simply means strong. Java is designed to eliminate certain types of programming errors. Java is strongly typed, which allows extensive compile-time error checking. It does not support memory pointers, which eliminates the possibility of overwriting memory and corrupting data. In addition, its automatic memory management (garbage collection) eliminates memory leaks and other problems associated with dynamic memory allocation/de-allocation.

4. Platform Independent

Unlike other programming languages such as C, C++ etc which are compiled into platform specific machines. Java is guaranteed to be write-once, run-anywhere language.On compilation Java program is compiled into bytecode. This bytecode is platform independent and can be run on any machine, plus this bytecode format also provide security. Any machine with Java Runtime Environment can run Java Programs.Java is platform Independent Language

5. Secure

When it comes to security, Java is always the first choice. With java secure features it enable us to develop virus free, temper free system. Java program always runs in Java runtime environment with almost null interaction with system OS, hence it is more secure. Java is designed to be secure in a networked environment too. The Java runtime environment uses a bytecode verification process to ensure that code loaded over the network does not violate Java security constraints.

6. Multi Threading

Java multithreading feature makes it possible to write program that can do many tasks simultaneously. Benefit of multithreading is that it utilizes same memory and other resources to execute multiple threads at the same time, like While typing, grammatical errors are checked along.

7. Architectural Neutral

Compiler generates bytecodes, which have nothing to do with a particular computer architecture, hence a Java program is easy to intrepret on any machine.

Xpanxion Mumbai Interview Questions latest 2020

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All The question of  Xpanxion Round 1st Clear. All type of core Java Question Asking in Xpanxion Company. Interview Questions in Mumbai Xpanxion

Interview Question for Xpanxion Mumbai.

Que 1. What is dot operator ?

Ans:-    The dot operator(.) is used to access the

              instance varibles and methods of class

     objects.it is also used to access classes and

     sub-packages from a package.

===================================================================

Que 2. List any five features of Java ?

Ans:-    Some features include Object Oriented, platform 

             Independent, Robust,interpreted,Multi-threaded.

===================================================================

Que 3. Why deletion in LinkList is fast than ArrayList ?

Ans:-     Deletion in linked list is fast because it involves only

               updating the next pointer in the node before the 

      deleted node and updating the previous pointer in 

              the node after the deleted node.

===================================================================

Que 4. How do you decide when to use ArrayList and LinkList ?

Ans:-     if you need to frequently add and remove elements 

              from the middle of the list and only access the list

             elements sequentially, then LinkList should be used.

             if you need to support random access, without 

             inserting or removing elements from any place 

            other than the end, than ArrayList should be used.

===================================================================

Que 5. What are synchronized methods and synchronized statements ?

Ans:-     synchronized methods are methods that are used to control 

               access to an object.A thread only executes a synchronized method

              after has acquired the lock of the methods object or class. 

              Synchronized Statements are similar to synchronized methods.

             A synchronized statements can only be executed after a thread has 

             acquired the lock of the object or class referenced 

            in the synchronized statement.

===================================================================

Que 6.  What is Polymorphism in Java ? 

Ans:-      Polymorphism is the ability to of an object to take 

       on many forms.The most common use of polymorphism 

               in OOP occur when a parent class reference is used

       to refer to a child class object.

===================================================================

Que 7.  What are native methods? How do you use them ?

Ans:-     Native methods are methods whose implementation is provided 

              in another programming language  such as C.The main objective of native

             method are to improve th performance of the system.

===================================================================

Que 8. What is HAS-A relationship in Java ?

Ans:-     1. HAS-A Relationship is also knows as composition(or) aggregation.

               2. There is no specific keyword to implement HAS-A relationship but mostly 

                   we can use new operator.

              3. The main advantage of  reusability.

===================================================================

Que 9. What is Encapsulation ?

Ans:-     Binding a data and corresponding method in a single 

              unit is called encapsulation.If any class follows data 

      hiding and abstraction such type of class is called encapsulated class.

             ENCAPSULATION= ABSTRACTION+DATA HIDING

===================================================================

 learn java Is for All The java Lover and java beginners.
 Learn java provide java interview preparations Questions And Answers .
 we will do over best for all the java devlopers.
 As a Java professional, it is essential to know the right things
 learn the java technologies and prepare the right answers to commonly 
 asked Java Interview Questions. 
 Here’s a definitive list of top Java Interview Questions that will 
 guarantee a breeze-through to the next level. 

Interview Questions and Answers for Xpanxion 2020 Letest Questions & Answers 2020

 Interview Questions and Answers for Xpanxion 2020 Letest Questions & Ans

All The question of  Xpanxion Round 1st Clear. All type of core Java Question Asking in Xpanxion Company.

Que 1.   Give a few reasons for using java ?   

Ans:-           Built-in support for multi-threading ,socket communications,                                                                             and memory management. object oriented ,better portability                                                                             then other languages across operating system.support web based                                                                  applications,distributed applications.etc

              

              

Que 2. Tell Me Somthing About OOP'S Concept ?

Ans:-      OOP'S is called object oriented programming.
                  It is a programming  model in java.                                                                                                    OOP'S provide some concept to programming they are.
               1.      Abstraction.
              2.     Data Hiding.
              3.     Encapsulation.
              4.    Tightly encapsulation class.
              5.    IS-A Relationship(Inheritance).
              6    .HAS-A Relationship.
              7.    Method Singnature
              8    .Polymorphism
              9.   Static Control Flow.
            10.   Singleton Class.
            11.   Fectory Method.

Que 3. What is Polymorphism in Java ? 

Ans:-   Polymorphism is the ability to of an object to take 

on many forms.The most common use of polymorphism 

             in OOP occur when a parent class reference is used

to refer to a child class object.

Que 4. How many methods in Externalizable interface ?

Ans:-  There are two method in Externalizable interface.You have to implement these
            two methods in order to make your class externalizable. These two methods are
           1. readExternal().
           2. writeExternal().

Que 5. What is Iterator interface ?

Ans:-    The Iterator interface is used to step through the element of a Collection.

Que 6. What are native methods? How do you use them ?

Ans:-    Native methods are methods whose implementation is provided 
             in another programming language  such as C.The main objective of native
             method are to improve th performance of the system.

Que 7. What is HAS-A relationship in Java ?

Ans:-   1. HAS-A Relationship is also knows as composition(or) aggregation.
            2. There is no specific keyword to implement HAS-A relationship but mostly 
                 we can use new operator.
           3. The main advantage of  reusability.

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