Thread

 Process memory space = Heap

Each application has its own memory space, also known as the heap. 

The heap isn't shared between two applications or two processes, they each have their own.

A thread is a single unit of execution, within a process.

Each process can have multiple threads. Every application has at least one thread, and that is the main thread. 

Threads are fundamental building blocks, to support concurrency, in a java application. They are essential, because they allow us to perform multiple tasks simultaneously, within a single process. 

package org.example;

public class Main {
    public static void main(String[] args) {
        Thread currentThread = Thread.currentThread();
        System.out.println(currentThread.getClass().getName());
        System.out.println(currentThread);
        printThreadState(currentThread);
        currentThread.setName("MainGuy");
        currentThread.setPriority(Thread.MAX_PRIORITY);
        printThreadState(currentThread);
    }

    public static void printThreadState(Thread thread) {
        System.out.println("--------------------------");
        System.out.println("Thread ID: " + thread.getId());
        System.out.println("Thread Name: " + thread.getName());
        System.out.println("Thread Priority: " + thread.getPriority());
        System.out.println("Thread State: " + thread.getState());
        System.out.println("Thread Group: " + thread.getThreadGroup());
        System.out.println("Thread is alive: " + thread.isAlive());
        System.out.println("--------------------------");
    }
}

--- start

package org.example;

public class CustomThread extends Thread {

    @Override
    public void run() {
        for (int i = 1; i <= 5; i++) {
            System.out.print(" 1 ");
            try {
                Thread.sleep(500); // adding a 1-second delay between each count
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

package org.example;

import java.util.concurrent.TimeUnit;

public class Main {
    public static void main(String[] args) {
        Thread currentThread = Thread.currentThread();
        System.out.println(currentThread.getClass().getName());
        System.out.println(currentThread);
        printThreadState(currentThread);
        currentThread.setName("MainGuy");
        currentThread.setPriority(Thread.MAX_PRIORITY);
        printThreadState(currentThread);
        CustomThread customThread = new CustomThread();
        customThread.start();
        for (int i = 0; i < 3; i++) {
            System.out.print(" 0 ");
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void printThreadState(Thread thread) {
        System.out.println("--------------------------");
        System.out.println("Thread ID: " + thread.getId());
        System.out.println("Thread Name: " + thread.getName());
        System.out.println("Thread Priority: " + thread.getPriority());
        System.out.println("Thread State: " + thread.getState());
        System.out.println("Thread Group: " + thread.getThreadGroup());
        System.out.println("Thread is alive: " + thread.isAlive());
        System.out.println("--------------------------");
    }
}

-- run

package org.example;

import java.util.concurrent.TimeUnit;

public class Main {
    public static void main(String[] args) {
        Thread currentThread = Thread.currentThread();
        System.out.println(currentThread.getClass().getName());
        System.out.println(currentThread);
        printThreadState(currentThread);
        currentThread.setName("MainGuy");
        currentThread.setPriority(Thread.MAX_PRIORITY);
        printThreadState(currentThread);
        CustomThread customThread = new CustomThread();
        customThread.run();
        for (int i = 0; i < 3; i++) {
            System.out.print(" 0 ");
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void printThreadState(Thread thread) {
        System.out.println("--------------------------");
        System.out.println("Thread ID: " + thread.getId());
        System.out.println("Thread Name: " + thread.getName());
        System.out.println("Thread Priority: " + thread.getPriority());
        System.out.println("Thread State: " + thread.getState());
        System.out.println("Thread Group: " + thread.getThreadGroup());
        System.out.println("Thread is alive: " + thread.isAlive());
        System.out.println("--------------------------");
    }
}