How To Make a Age Calculator in Java

This is a age calculator made in java, it's a console application by the way :)

source :

 import java.util.GregorianCalendar;
import java.util.Scanner;
import java.util.InputMismatchException;

public class age_calculator {

    public static void main(String[] args) {
        int day = 0;
        int month = 0;
        int year = 0;
        Scanner scan = new Scanner(;
         System.out.print("Day: ");
         day = scan.nextInt();
         System.out.print("Month: ");
         month = scan.nextInt();
         System.out.print("Year: ");
         year = scan.nextInt();
  catch(InputMismatchException e){
   System.out.println("Error: You entered an invalid number");
        System.out.println("\nYou are " + getAge(day,month,year) + " years old");

    public static int getAge(int day, int month, int year){
  final int ERROR = -1;

        //initialize GregorianCalendar with current date
        GregorianCalendar cal = new GregorianCalendar();
        //constant holds current day
        final int CDAY = cal.get(GregorianCalendar.DAY_OF_MONTH);
        //constant hold current month
        final int CMONTH = cal.get(GregorianCalendar.MONTH) + 1;
        //constant to hold current year
        final int CYEAR = cal.get(GregorianCalendar.YEAR);
        //check if current day of the month is greater then birth day
        if (month == CMONTH){
            if(CDAY >= day)
                return CYEAR - year;
   if(CDAY < day)
    return CYEAR - year - 1;
        //check if birth month is less then current month
        else if(month < CMONTH)
            return CYEAR - year;
        //subtract 1 from the age because  the current day in the month is less then birth date
         return CYEAR - year - 1;
  return ERROR;


screenshot :
 How To Make a Age Calculator in Java
 Hope it helped you :)

How To Execute Shell Commands and Print Results in Java

Java Command Shell,bash script -eq, bash script -ne, best way to learn java, execute shell commands, execute shell commands java, get runtime, host runtime, java, java learning, oracle sql plsql, print results, tutorial,
There are many ways to execute shell commands and print results in java I guess, the famous and the most used way is Runtime.getRuntime().exec you can find a good explanation for that from here. Coming to the point i am using the same way but little different! I use BufferedReader,InputStreamReader for simplicity and I can't make it much advanced. On the main event I have created a String where you put your command with the second event it executes the command and prints the result before I start I would like to give some credits to luismcosta.

How To Make A Addition Calculator In Java Using JOption

How To Make A Addition Calculator In Java Using JOption
Okay guys today i will be teaching you how to make a simple addition calculator using Joption in java, I saw someone wrote some codes to calculate addition also it uses Java Scanner. This is that program .
import java.util.Scanner;

class basic_cal
  public static void main(String args[])
   Scanner shim = new Scanner(;
   double first_number,second_number,answer;
   System.out.println("Enter First Number : ");
   first_number = shim.nextDouble();
   System.out.println("Enter Second Number : ");
   second_number = shim.nextDouble();
   answer = first_number + second_number;
   System.out.println("Answer : " + answer);
Okay now i saw that and got an idea to make the same thing with Joption , Joption is like the messagebox we have in c# and ok , this is the program i wrote :