How to restrict the user to enter number between certain range in java?

Question

In Java, if you want to ask users, for example, to input numbers only between 1,000 and 100,000, the program would continue further. Otherwise, ask the user to input the number again in the given range.

Edit: Here, my program only tries to validate the input only once. How shall I make to ask the user to input until valid data(i.e between 1000-100000) is entered

public static void main(String args[]) {

    Scanner sc = new Scanner(System.in);    
    System.out.print("Principal:");
    double principal = sc.nextDouble();

    if(principal<1000 || principal >100000) {
        System.out.println("enter principal again:");
        principal = sc.nextDouble();        
    }
}

Does this answer your question? [Asking the user for input until they give a valid response](https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response) — craq, Jan 16 '20 at 21:41

score 1 · Answer 1 · answered Jan 16 '20 at 20:25

1

You can use do-while loop here as below

public static void main(String []args){
    Scanner in = new Scanner(System.in);
    int result;
   do {
       System.out.println("Enter value bw 1-100");
       result = in.nextInt();
   } while(result < 0 || result > 100);

    System.out.println("correct "+ result);

}

answered Jan 16 '20 at 20:25

Gunjan Mehta

66
6

Also need to handle the case where the user inputs garbage rather than an integer. – FredK Jan 16 '20 at 21:10
To check whether the input is an integer or not, you can use this link https://stackoverflow.com/questions/237159/whats-the-best-way-to-check-if-a-string-represents-an-integer-in-java – Nuwan Harshakumara Piyarathna Jan 17 '20 at 15:33
Can you also suggest a better alternative by using break and continue statements too? – Kalash Babu Acharya Jan 18 '20 at 17:31

score 0 · Answer 2 · answered Jan 17 '20 at 15:23

import java.io.*;
import java.util.*;
import java.lang.*;
import java.math.*;

class Myclass {

    static boolean isInteger(double number){
        return Math.ceil(number) == Math.floor(number); 
    }
    public static void main(String args[]) {

        Scanner in = new Scanner(System.in);    
        double num;
        do{
            System.out.print("Enter a integer between 1000 and 100000 : ");
            num = in.nextDouble();
        }
        while((num < 1000 || num > 100000)||(!isInteger(num)));

        System.out.println("Validated input  : "+num);

    }
}

Hope this helps you

How to restrict the user to enter number between certain range in java?

2 Answers2