Introduction to Thread and Creating Main Thread in Java

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In this lesson, you will learn.

• What is a Thread
• Understanding Main Thread
• Examples
• Methods of a Thread Class

What is a Thread in Java?

1. In Java, a thread represents a separate execution path within a program.
2. A thread is an independent, virtual, and sequential control flow within a process
3. It allows a program to perform multiple tasks concurrently, making optimal use of the CPU.

A single-threaded application can perform only one task at a time. It waits for one task to be completed before another can start. As a result, the efficiency of the application is hampered.

Multiple or Multithreading model helps to perform multiple tasks simultaneously, which saves time and improves the execution speed and efficiency of the application.

It involves multiple threads and each thread shares the same memory space. Each thread performs the job independently of another thread. 

Understanding The Main Thread

When a Java program starts up, the one thread begins running immediately known as your program’s main thread.

• The main thread is the initial thread from which all other child threads are spawned.
• Often, it must be the last thread to finish execution because it performs various shutdown actions also.
• The main thread is created automatically when your program is started, it can be controlled through a Thread (Built-in Class) object.

The method currentThread( ), which is a public static member of a Thread class returns a reference to the thread in which it is called.

Syntax

static Thread currentThread( )

Example: Creating a Main Thread

package mainthread;

public class MainThreadExample {

	public static void main(String[] args) {
		// Get the current thread which is the main thread
		Thread t = Thread.currentThread(); 
        System.out.println("Current thread: " + t);
        
        System.out.println("Current thread: " + t.getName());
        // Changing the name of the main thread
        t.setName("PrimaryThread");
        System.out.println("After name change: " + t.getName());
        
        // Output details about the main thread
        System.out.println("Main thread details: " + t);
        
     // Simple loop to demonstrate the thread execution
        for (int i = 0; i < 5; i++) {
            System.out.println(i);
            try {
                Thread.sleep(400); // Pause the main thread for 400 milliseconds
            } catch (InterruptedException e) {
                System.out.println("Main thread interrupted.");
            }
        }

	}

}

Output

Current thread: Thread[main,5,main]
Current thread: main
After name change: PrimaryThread
Main thread details: Thread[PrimaryThread,5,main]
0
1
2
3
4

Explanation

Thread[main,5,main], This displays, in order: the name of the thread, its priority, and the name of its group.

By default, the name of the main thread is main. Its priority is 5, which is the default value, and main is the name of the group of threads to which this thread belongs.

The sleep( ) method pauses or suspends the thread execution by a specified period of milliseconds and throws InterruptedException,

Syntax: sleep() Methods

static void sleep(long milliseconds) throws InterruptedException
static void sleep(long milliseconds, int nanoseconds) throws InterruptedException

Methods of a Thread Class

Here’s a table that outlines some of the key methods of the Thread class along with a brief explanation and example for each.

End of the lesson….enjoy learning

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