Thread: How to limit users to enter only 12 digit input and an integer value in Java?

Hi Java professionals,
I want to limit the program to only accept a 12 digit input and an integer value but I don't know how to program it,please help.

import java.util.Scanner;
public class testing4
{
public static void main(String []args)
{
Scanner reader = new Scanner(System.in);
String input;

do {
System.out.print("Please enter a 12 digit number:");
input = reader.nextLine();
}while( input.length()!=12);
System.out.println("Thanks.");
}
}

hi,

you can use the if condition after the getting input from the user.

if(input.length()==12)
{
//allow
}

Still you have doubts or queries post here pls.

Thanks,

Hi,
but I need to loop it if the input is incorrect,do you have any other advice?

--- Update ---

I mean the program needs to loop and it only accepts a numeric input.

yes you can use your same condition in do..while

do { 
System.out.print("Please enter a 12 digit number:"); 
input = reader.nextLine(); 
if(input.length()==12){
	//allow
 
}
 
}while( input.length()!=12);

Thanks,

Thanks but my program must not accept any letter or symbol and it must only accepts numbers,please advise.

Hi,

K do one thing, try to parse your input to integer using Integer.parseInt(your_input). Use try and catch statement.

If you entered string means it throws an error in catch statement you can display "It is not a valid number" otherwise program flow goes well.

do
{
try
{
//getInput
//use Integer.parseInt(getInput) convert to int
}
catch(Exception e)
{
//Print "It is not a valid number"
}
}while(**Yourconditon**);

If you face any difficulties post here. Happy to help

Thanks,

@Loh Jane: Please post your code in code/highlight tags. You can learn how with other useful info for newcomers at this link.