Concurrency and Multithreading

In modern software development, concurrency and multithreading are crucial concepts to understand.

Concurrency refers to the ability of a program to execute multiple tasks concurrently. It allows multiple threads to make progress simultaneously, improving overall performance and resource utilization.

Multithreading, on the other hand, is the ability of an operating system or a Java program to manage multiple threads concurrently. Threads are lightweight processes within a program that can execute independently and share common resources.

Benefits of Concurrency and Multithreading

Concurrency and multithreading offer several benefits:

• Improved performance: By allowing multiple threads to execute simultaneously, programs can take advantage of multiple processing units and distribute the workload effectively.
• Responsive user interfaces: In graphical user interface (GUI) applications, using multithreading ensures that the user interface remains responsive while performing time-consuming tasks in the background.
• Efficient resource utilization: Concurrent programming allows programs to allocate resources efficiently by running tasks concurrently and avoiding idle time.
• Simplified programming: Java's built-in support for concurrency and multithreading makes it easier to write concurrent programs by providing high-level abstractions and synchronization mechanisms.

Example: Creating and Running Threads

To illustrate the concept of multithreading, let's consider an example where we create two threads that execute concurrently. Each thread will print its name and a counter from 1 to 5.

1public class Main {
2
3  public static void main(String[] args) {
4    // Custom Thread class
5    MyThread thread1 = new MyThread("Thread 1");
6    MyThread thread2 = new MyThread("Thread 2");
7    
8    // Start the threads
9    thread1.start();
10    thread2.start();
11  }
12
13  static class MyThread extends Thread {
14    private String name;
15    
16    public MyThread(String name) {
17      this.name = name;
18    }
19
20    @Override
21    public void run() {
22      for (int i = 1; i <= 5; i++) {
23        System.out.println(name + ": " + i);
24        try {
25          sleep(1000);
26        } catch (InterruptedException e) {
27          e.printStackTrace();
28        }
29      }
30    }
31  }
32}

In the above example, we define a custom MyThread class that extends the Thread class. Each thread has a name and prints its name along with a counter from 1 to 5. The sleep() method is used to introduce a delay of 1 second between each iteration to simulate concurrent execution.

When we run the program, we can observe that both threads execute concurrently and print their respective output.

Output:

1Thread 1: 1
2Thread 2: 1
3Thread 1: 2
4Thread 2: 2
5Thread 1: 3
6Thread 2: 3
7Thread 1: 4
8Thread 2: 4
9Thread 1: 5
10Thread 2: 5

This example demonstrates the basic concept of multithreading in Java. It shows how multiple threads can execute concurrently, allowing tasks to be performed in parallel.

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}

public class Main {

​

  public static void main(String[] args) {

    // Custom Thread class

    MyThread thread1 = new MyThread("Thread 1");

    MyThread thread2 = new MyThread("Thread 2");

    // Start the threads

    thread1.start();

    thread2.start();

  }

​

  static class MyThread extends Thread {

    private String name;

    public MyThread(String name) {

      this.name = name;

    }

​

    @Override

    public void run() {

      for (int i = 1; i <= 5; i++) {

        System.out.println(name + ": " + i);

        try {

          sleep(1000);

        } catch (InterruptedException e) {

          e.printStackTrace();

        }

      }