JAVA program to print all prime numbers between two user given numbers

JAVA program to print all prime numbers between two user given numbers.

import java.io.*;
public class MyMain {
public static void main(String[] args) {
// TODO Auto-generated method stub
InputStreamReader istream = new InputStreamReader(System.in) ;
        BufferedReader read = new BufferedReader(istream) ;
        System.out.print("Enter the first number: ");
        int num1=0, num2=0;
        try{
            num1=Integer.parseInt(read.readLine() );
            System.out.print("Enter the second number: ");
            num2=Integer.parseInt(read.readLine() );
            if(num1>=num2){ //Checking for valid range
            System.out.println("The first number should must be less than the second number.");
            }
            else{
            for(int i=num1;i<=num2;i++){
            int count = 0; //Setting a counter
            for(int j=1;j<=i;j++){
            if(i%j==0) count++;
            }
            if(count == 2)
            System.out.println(i+ " is a prime number.");
            else
            System.out.println(i+ " is a non-prime number.");
            }
            }
           
        } catch(Exception Number){
            System.out.println("Invalid Number!");
        }
           
}
}

Output: 

Enter the first number: 12
Enter the second number: 23
12 is a non-prime number.
13 is a prime number.
14 is a non-prime number.
15 is a non-prime number.
16 is a non-prime number.
17 is a prime number.
18 is a non-prime number.
19 is a prime number.
20 is a non-prime number.
21 is a non-prime number.
22 is a non-prime number.
23 is a prime number.

JAVA program to check for a prime number

Write a JAVA program to check whether a number is prime or not.

import java.io.*;
public class PrimeCheck {
public static void main(String[] args) {
// TODO Auto-generated method stub
InputStreamReader istream = new InputStreamReader(System.in) ;
        BufferedReader read = new BufferedReader(istream) ;
        System.out.print("Enter the number: ");
        int num=0;
        try{
            num=Integer.parseInt(read.readLine() );
            int count = 0;
            for(int i=1;i<=num;i++){
            if(num%i == 0) count++;
            }
            if(count == 2) {
            System.out.println("The number "+num+" is prime.");
            }
            else{
            System.out.println("The number "+num+" is not prime.");
            }
        } catch(Exception Number){
            System.out.println("Invalid Number!");
        }
           
}
}

JAVA print a line

Write a JAVA program to print a line of *. The length of line will be given as user input.

import java.io.*;
public class MyMain {
public static void main(String[] args) {
// TODO Auto-generated method stub
InputStreamReader istream = new InputStreamReader(System.in) ;
        BufferedReader read = new BufferedReader(istream) ;
        System.out.print("Enter Line Size : ");
        int num=0;
        try{
            num=Integer.parseInt(read.readLine() );
        } catch(Exception Number){
            System.out.println("Invalid Number!");
        }
            for(int i=1;i<=num;i++){
                    System.out.print("*");
                }
}
}

Java create a upside down triangle pattern



import java.io.*;

public class triangle {

    public static void main ( String arg[] ){

        InputStreamReader istream = new InputStreamReader(System.in) ;

        BufferedReader read = new BufferedReader(istream) ;

        System.out.print("Enter Triangle Size : ");

        int num=0;

        try{

            num=Integer.parseInt( read.readLine() );

        } catch(Exception Number){

            System.out.println("Invalid Number!");       

            for(int i=1;i<=num;i++){

                for(int j=i;j>1;j--){

                    System.out.print(" ");

                }

                for(int k=1;k<=num-(i-1);k++){

                    System.out.print("*");

                    for(int k1=1;k1<k;k1+=k){

                        System.out.print("*");

                    }

                }

                System.out.println();         

    }

}

Java create a triangle pattern





import java.io.*;

public class triangle {

    public static void main ( String arg[] ){

        InputStreamReader istream = new InputStreamReader(System.in) ;

        BufferedReader read = new BufferedReader(istream) ;

        System.out.print("Enter Triangle Size : ");

        int num=0;

        try{

            num=Integer.parseInt( read.readLine() );

        } catch(Exception Number){

            System.out.println("Invalid Number!");

        }

            for(int i=1;i<=num;i++){

                for(int j=1;j<num-(i-1);j++){

                    System.out.print(" ");

                }

                for(int k=1;k<=i;k++){

                    System.out.print("*");

                    for(int k1=1;k1<k;k1+=k){

                        System.out.print("*");

                    }

                }

                System.out.println();

            }

    }

}