Thread Methods in Java

Following are the some important methods available in thread class.

MethodsDescription
public void start( )This method invokes the run() method, which causes the thread to begin its execution.
public void run( )Contains the actual functionality of a thread and is usually invoked by start() method.
public static void sleep (long millisec)Blocks currently running thread for at least certain millisecond.
public static void yield ( )Causes the current running thread to halt temporarily and allow other threads to execute.
public static Thread currentThread ( )It returns the reference to the current running thread object.
public final void setPriority (int priority)Changes the priority of the current thread. The minimum priority number is 1 and the maximum priority number is 10.
public final void join (long millisec)Allows one thread to wait for completion of another thread.
public final boolean isAlive ( )Used to know whether a thread is live or not. It returns true if the thread is alive. A thread is said to be alive if it has been started but has not yet died.
public void interrupt ( )Interrupts the thread, causing it to continue execution if it was blocked for some reason.

Thread Priorities

Thread priorities is the integer number from 1 to 10 which helps to determine the order in which threads are to be scheduled. It decides when to switch from one running thread to another thread.

Priority range of MIN_PRIORITY is 1 and MAX_PRIORITY is 10. Default value of NORMAL_PRIORITY is 5.

Daemon Thread

  • Daemon thread is the low priority thread which runs in the background to perform garbage collection.
  • It always depends on user threads.
  • JVM does not have control over daemon thread. It can keep running even when the program has stopped.

Example : Program to create a daemon thread in Java

public class DaemonThreadDemo extends Thread
{  
     public void run()
     {  
         if(Thread.currentThread().isDaemon())
         {
               System.out.println("Daemon Thread");  
         }  
         else
         {  
               System.out.println("User Thread");  
         }  
     }  
     public static void main(String[] args)
     {  
         DaemonThreadDemo t1 = new DaemonThreadDemo();
         DaemonThreadDemo t2 = new DaemonThreadDemo();  
         DaemonThreadDemo t3 = new DaemonThreadDemo();  
         t1.setDaemon(true);
         t1.start();
         t2.start();  
         t3.start();  
     }  
}


Output:
Daemon Thread
User Thread
User Thread
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