#Multithreading in Java

ritwin59 — Thu, 25 Nov 2021 13:25:14 +0000

Multithreading

Multithreading is a Java feature that allows concurrent execution of two or more parts of a program for maximum utilization of CPU. Each part of such program is called a thread. So, threads are light-weight processes within a process.

Threads can be created by using two mechanisms :

1.Extending the Thread class 

2.Implementing the Runnable Interface

Extending the Thread class

Thread creation by extending the Thread class
We create a class that extends the java.lang.Thread class. This class overrides the run() method available in the Thread class. A thread begins its life inside run() method. We create an object of our new class and call start() method to start the execution of a thread. Start() invokes the run() method on the Thread object.

Example:

class MultithreadingDemo extends Thread {
public void run()
{
try {
// Displaying the thread that is running
System.out.println(
"Thread " + Thread.currentThread().getId()
+ " is running");
}
catch (Exception e) {
// Throwing an exception
System.out.println("Exception is caught");
}
}
}
// Main Class
public class Multithread {
public static void main(String[] args)
{
int n = 8; // Number of threads
for (int i = 0; i < n; i++) {
MultithreadingDemo object
= new MultithreadingDemo();
object.start();
}
}
}

Output

Thread 15 is running
Thread 14 is running
Thread 16 is running
Thread 12 is running
Thread 11 is running
Thread 13 is running
Thread 18 is running
Thread 17 is running

Implementing the Runnable Interface

Thread creation by implementing the Runnable Interface
We create a new class which implements java.lang.Runnable interface and override run() method. Then we instantiate a Thread object and call start() method on this object.

// Java code for thread creation by implementing
// the Runnable Interface
class MultithreadingDemo implements Runnable {
public void run()
{
try {
// Displaying the thread that is running
System.out.println(
"Thread " + Thread.currentThread().getId()
+ " is running");
}
catch (Exception e) {
// Throwing an exception
System.out.println("Exception is caught");
}
}
}

// Main Class
class Multithread {
public static void main(String[] args)
{
int n = 8; // Number of threads
for (int i = 0; i < n; i++) {
Thread object
= new Thread(new MultithreadingDemo());
object.start();
}
}
}
Output

Thread 13 is running
Thread 11 is running
Thread 12 is running
Thread 15 is running
Thread 14 is running
Thread 18 is running
Thread 17 is running
Thread 16 is running

Thread Class vs Runnable Interface

If we extend the Thread class, our class cannot extend any other class because Java doesn’t support multiple inheritance. But, if we implement the Runnable interface, our class can still extend other base classes.
We can achieve basic functionality of a thread by extending Thread class because it provides some inbuilt methods like yield(), interrupt() etc. that are not available in Runnable interface.
Using runnable will give you an object that can be shared amongst multiple threads.

User Defined Function In C

ritwin59 — Tue, 11 May 2021 12:46:10 +0000

C programming language allows coders to define functions to perform special tasks. As functions are defined by users, they are called user-defined functions.

user-defined functions have contained the block of statements which are written by the user to perform a task

function has three related elements, in order to establish the function

Function declaration
function call
Function definition

EXAMPLE:
include
include
int sumNum(int x,int y); //function declaration
int main()
{
int i,j,sum;
printf("Please enter 2 numbers for find sum\n");
scanf("%d %d",&i,&j);
sum=sumNum(i,j); //function call
printf("The result of sum is :%d",sum);
getch();
return 0;
}
int sumNum(int x, int y)//function definition
{
int result;
result=x+y;
return result; //return statements
}

Declaration of the user-defined function.

A function declaration is a frame (prototype)of function that contains the function’s name, list of parameter and return type and ends with the semicolon. but it doesn’t,t contain the function body

Syntax

return_Type function_Name(parameter1,parameter2,......);

Example

int sum_Num(int x, int y,.........);

Calling a function

Syntax

function_Name(Argument list);

Example

sum_Num(argument_1, argument_2,.......);

Function Definition

The function definition is an expansion of function declaration. It contains codes in the body part of the function for execution program by the compiler – it contains the block of code for the special task

Syntax:

return_Type function_name(parameter_1, parameter_2,....){
//statements
//body of the function
}

Return statements:

Return statements terminate the execution of the function and return value to calling the function. Also, return statements control of the program control and moved to the calling function.

Syntax

return (expression);

Example

return (result);
return (x+y);

Example

include
include
int division(int x,int y); //function declaration or prototype
int main()
{
int i,j,div;
printf("Please enter 2 numbers for division\n");
scanf("%d%d",&i,&j);
div=division(i,j); //function call
printf("The result of division is :%d",div);
getch();
return 0;
}
int division(int i, int j)
{
int result;
result=i/j;
return result; //return statements
}

DEV Community: ritwin59

#Multithreading in Java

Multithreading

Threads can be created by using two mechanisms :

Extending the Thread class

Example:

Implementing the Runnable Interface

Thread Class vs Runnable Interface

User Defined Function In C

Declaration of the user-defined function.

Calling a function

Function Definition

Return statements: