Introduction

• Thread is the pre-defined class in Java which is used to create and manage threads (independent paths of execution).
• Thread class is present in the java.lang package.
• Syntax :-

  package java.lang;
  
  public class Thread extends Object implements Runnable
  {
      // Fields
      // Constructors
      // Methods
  }

• Threads are used to perform multitasking in Java programs.
  • Handling multiple client requests simultaneously (Servers)
  • Performing background tasks (file download, DB query, etc.)
  • Improving performance by parallel execution

Constructors of Thread Class:

• Below are the constructors of Thread class with examples:

• Below is the program for constructors of Thread class:

  • // Demonstration of Thread class constructors
    class MyRunnable implements Runnable
    {
        public void run()
        {
            System.out.println(Thread.currentThread().getName() + " is running...");
        }
    }
    
    public class ThreadConstructorsDemo
    {
        public static void main(String[] args)
        {    
            // 1. Default constructor
            Thread t1 = new Thread();
            System.out.println("Thread t1 (default): " + t1.getName());
    
            // 2. Thread(Runnable target)
            Thread t2 = new Thread(new MyRunnable());
            t2.setName("RunnableThread");
            t2.start();
    
            // 3. Thread(Runnable target, String name)
            Thread t3 = new Thread(new MyRunnable(), "Worker-1");
            t3.start();
    
            // 4. Thread(String name)
            Thread t4 = new Thread("HelperThread");
            System.out.println("Thread t4 (only name): " + t4.getName());
    
            // 5. Thread(ThreadGroup group, Runnable target)
            ThreadGroup g1 = new ThreadGroup("GroupA");
            Thread t5 = new Thread(g1, new MyRunnable());
            t5.setName("GroupThread-1");
            t5.start();
    
            // 6. Thread(ThreadGroup group, Runnable target, String name)
            ThreadGroup g2 = new ThreadGroup("GroupB");
            Thread t6 = new Thread(g2, new MyRunnable(), "GroupThread-2");
            t6.start();
    
            // 7. Thread(ThreadGroup group, Runnable target, String name, long stackSize)
            ThreadGroup g3 = new ThreadGroup("GroupC");
            Thread t7 = new Thread(g3, new MyRunnable(), "GroupThread-3", 1024);
            t7.start();
        }
    }

    Output:

    Thread t1 (default): Thread-0
    RunnableThread is running...
    Worker-1 is running...
    Thread t4 (only name): HelperThread
    GroupThread-1 is running...
    GroupThread-2 is running...
    GroupThread-3 is running...

Methods of Thread Class:

• Below are some common and important methods of Thread class:

• These all methods are explained deeply in next tutorials.