how to create threads and it's methods

How to create Threads in Java?

Threads can be created by using two ways

1) Extending the Thread class

2) Implementing the Runnable Interface

 
Thread Class

Thread class provides methods and constructors to create and perform operations on a thread.

Thread class extends Object class and implements Runnable interface.

 

Steps to create a thread using Thread class

1) Create a class and extend class with Thread

2) Override run() method, provide body/ write logic inside run() method.

3) Invoke start() method.

 

What is run() & start() method detailed information available in thread class method explanation part.

Example Program:

Output:

 

Thread Class methods:

run(), start(), sleep(), join(), yield(), getId() etc.,

 

start() & run() methods

as we know we can create in two ways i.e., extending thread class and implementing runnable interface in both ways we need to provide body/ write logic inside run() method.

Actually run() method is body of thread.

But we can’t call run method directly if we call run() method directly it will executes as a normal program and it is not considered as a separate thread.

run() method doesn’t create separate stack for the new thread.

start() method is responsible for the execution of run() method.

so instead of calling run() method directly we should call start() method

start() method has a capability to create a new stack.

After invoking start() method, JVM create runtime stack for the particular thread.

That method body/run() of thread will be executed.

After executing the method that corresponding method will be removed from the stack.

sleep() method

The sleep() & sleep(Long milliseconds)method is used to pause the execution of a thread for a specific time.

join() method

The join() method in java is used to pause the execution of a current thread until unless the specified thread is dead.

Suppose we have two threads thread1 and thread2. We want the thread2 should be executed after the thread1.

We can achieve it by calling the thread1.join() while thread2 is executing. 

The join() method is used for adding sequencing between multiple threads e.g. one thread starts execution after first thread finishes its execution.

yield() method

The yield() method in Java is used to give the hint to thread scheduler and gives the chance to other threads

A real-life example of the yield() method

Let’s say we have two threads, which are thread1, thread2, and both threads have the same priority.

The thread1 using the processor time and it is in running state. The thread2 is in a RUNNABLE state.

The completion time of thread1 is 1 hour and the completion time of thread2 is 5 minutes.

So thread2 must wait for 1 hour to just finish the 5-minute job.

In such type of scenarios where one thread is taking too much time to complete its execution and other important threads are waiting.

Here can use the yield() method and give the chance to execute the other threads.

The yield) method gives the hint to thread scheduler, The thread scheduler can take the action, or it can ignore the hint.

Thread1.yield()  -> here Thread1 give chance to other threads so after completion of others then only Thread1 execute

  

 

Runnable Interface

The Runnable Interface should be executed by any class, that class instances are should be executed by Thread.

Runnable Interface have only one method i.e., run().

 

Steps to create a thread using Runnable Interface

1) Create a class and implements runnable interface

2) Override run() method, provide body/ write logic inside run() method.

3) Create an implementation class instance.

4) Create a Thread class object and pass implementation class instance inside Thread class constructor.

5) Invoke start() method.

  

Example Program:

Output: