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Java program to find the prime number.

                         Let us see the java program to find the prime number. so first we should know about prime number. and logic to write a program, get to know about them below.

Content.
  1. What is prime number.
  2. Logic for program.
  3. Program.
  4. Explanation.
  5. Output.


What is prime number?
                Prime number is the number which can divide by 1 and itself only.
Example:
                2,3,5,7,11...

Logic for the Program.
  • We need to give limits to start and end the prime number.
  • Then make the number between the limits divide each other, if the reminder is a zero then it is prime number. if we get any number other then zero it is not a prime number it does of come in sequence.
  • we use for loop and if statement.


Program

import java.io.*;
class prime
{
  public static void main(String args[]) throws IOException
  {
    int n,m,i,j,c;
    InputStreamReader read = new InputStreamReader(System.in);
    BufferedReader in=new BufferedReader(read);
  System.out.println("Enter lower limit");
      n=Integer.parseInt(in.readLine());
  System.out.println("Enter upper limit");
      m=Integer.parseInt(in.readLine());
  System.out.println("Prime numbers between are :");
      for(i=n;i<=m;i++)
        {
          c=0;
          for(j=1;j<=i;j++)
            {
              if(i%j==0)
                 c=c+1;
             }
   if(c==2)
   System.out.println(i);
}
}
}


Explanation.
  • We have given the class name has prime.
  • public static void main(String arg[]) refers to add a method i.e array of strong method to the program.
  • String A,B, int x,y, char c is declaring the variable, s is declared to store 0. 
  • InputStreamReader read = new InputStreamReader(System.in); we create this object because we need to give the value to variable at the time of execution, this is a one of the way to give value to a variable.
  • BufferedReader in = new BufferedReader(read); we create this object because, we need a buffer to store the value of the variable.
  • Now, we have to give condition which satisfies all the above in the logic for the program. 
  • I choose,  for loop with i=n;i<=m;i++ as condition and it is nest with  for loop with j=n;j<=m;j++.
  • Then it as if statem to check for prime number.
  • n is the lower limit we give, m is upper limit.
  • System.out.println is used to display the given in output screen(make sure S in System is capital)
Know more about if statement.
Know more about for loop here.

Output:

       Compile : javac prime.java
       Run        : java prim
        Enter lower limit
        0
        Enter upper limit
        20
        Prime numbers between are :
        2
        3
        5
        7
        11
        13
        17
        19


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