Java Prime Number,Java Prime Number Program,Prime Number Example in Java

Prime Number in Java

This Java programming tutorial, we will be read how to get prime number between 1 to given number. First of all we have to define a class "PrimeNumber". Java I/O package has a input stream and a output stream in which input stream is used for reading the stream and memory allocating and the output stream used for writing bytes. As in this program we are going to insert certain instruction by creating buffer reader class. Here we have to create a buffer for the string class that can be used to instantiate a changeable object for storing and processing a string of character. Now use the ParseInt method for converting the parses the string argument and define 'num' as an integer.

Now applying in this program we use two 'for' loop. For loop will start from 1 to entered number. And another loop will start and divide it from 2 to less than those number. If number is divided by any number that means it is not prime otherwise prime number.

Here is the code of the Program


import java.io.*;



class PrimeNumber {

  public static void main(String[] args) throws Exception{

    int i;

    BufferedReader bf = new BufferedReader(

              new InputStreamReader(System.in));

    System.out.println("Enter number:");

    int num = Integer.parseInt(bf.readLine());

    System.out.println("Prime number: ");

    for (i=1; i < num; i++ ){

      int j;

      for (j=2; j<i; j++){

        int n = i%j;

        if (n==0){

          break;

        }

      }

      if(i == j){

        System.out.print("  "+i);

      }

    }

  }

}

Current Comments

8 comments so far (post your own) View All Comments Latest 10 Comments:

Couldn't understand the code where it says:
if(i == j)
Can anyone explain me this bit?y do we need that for?

Posted by sal85 on Saturday, 09.6.08 @ 08:43am | #77419

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Actually Connection is an interface in jdbc,without creating a class how can we get a method inside connection interface?

Posted by neelakandan on Monday, 08.25.08 @ 11:28am | #74972

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regarding bufferreader-is it able to use datainputstream instead.

really this tuts help me a lot!

nith wishes----------naveen

Posted by naveen on Monday, 03.24.08 @ 10:17am | #54032

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I really respect who has developed this website and uploaded the easy and good programs. i really like this webiste and due to this website i have got A+ in my final exams in java. i have not touched even my course book.
I really like it keep it up and please upload the easy codes for asp.net also.
Best Regards,
Mirza
IT Administrator

Posted by Mirza on Wednesday, 08.8.07 @ 13:25pm | #22922

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I cant understand what "throws Exception" do

Posted by heba on Saturday, 04.21.07 @ 23:20pm | #14696

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how to write given no is prime or not plz provide code for that

Posted by shivaji on Friday, 03.30.07 @ 12:47pm | #12977

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ok i solved the prob

Posted by kasia on Thursday, 03.8.07 @ 03:59am | #11063

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tutorials so far word fine till i got 2 this one and
i get an error on line 18
int num = Integer.parseInt(bf.readLine());

with bf.readLine();

Posted by kasia on Thursday, 03.8.07 @ 03:49am | #11061

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