提示用户重新输入整数直到输入二进制数

Question

I am new with JAVA (computer programming by the way). The following program checks if the input is binary or not. And it should prompt user to re-enter integers until binary number is entered. But this program is doing exactly opposite. It is asking me to re-enter integers if input is binary, and the program terminates when non-binary is entered. I need a serious help, please. Here is my output

    public static void main(String[] args) {

    int value, userValue;
    int binaryDigit = 0, notBinaryDigit = 0;

    Scanner scan = new Scanner(System.in);

    while (true) {
        System.out.println("Please enter positive integers: ");

        userValue = scan.nextInt();
        value = userValue;

        while (userValue > 0) {
            if ((userValue % 10 == 0) || (userValue % 10 == 1)) {
                binaryDigit++;
            } else {
                notBinaryDigit++;
            }

            userValue = userValue / 10;

        }

        if (notBinaryDigit > 0) {
            System.out.println(value + " is a not a Binary Number.");
            break;
        } else {
            System.out.println(value + " is  a  Binary Number.");

        }

    }
}

Answer 1

It might be too late for the answer. But the code can be simplified much if you make use of the method.

import java.util.Scanner;

public class MainClass {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        while (true) {
            System.out.println("Please enter positive integers: ");
            int userValue = scan.nextInt();
            if (isBinary(userValue)) {
                System.out.println(userValue + " is a Binary Number.");
                break;
            } else {
                System.out.println(userValue + " is  a not Binary Number.");
            }
        }
    }

    public static boolean isBinary(int input) {
        while (input > 0) {
            if ((input % 10 != 0) && (input % 10 != 1)) {
                return false;
            }
            input = input / 10;
        }
        return true;
    }
}

Answer 2

Change your code

from this

  if (notBinaryDigit > 0) {
        System.out.println(value + " is a not a Binary Number.");
        break;
    } else {
        System.out.println(value + " is  a  Binary Number.");

    }

to this

 if (notBinaryDigit > 0) {
        System.out.println(value + " is a not a Binary Number.");
        notBinaryDigit--;
    } if(binaryDigit >0 {
        System.out.println(value + " is  a  Binary Number.");
 binaryDigit--;
  break;
    }

and it will ask for values and tell if it is binary or not and it terminates if it is binary

Answer 3

Error coming due to Scanner class. you can run your program and check your logic by removing the Scanner class like this.

public class Test{

public static void main(String []args){

    int value, userValue=34;
    int binaryDigit = 0, notBinaryDigit = 0;
    value = userValue;

    while (userValue > 0) {
        if ((userValue % 10 == 0) || (userValue % 10 == 1)) {
                binaryDigit++;
            } else {
                notBinaryDigit++;
            }

            userValue = userValue / 10;

        }

        if (notBinaryDigit > 0) {
            System.out.println(value + " is a not a Binary Number.");

        } else {
            System.out.println(value + " is  a  Binary Number.");

        }
}

}