Question

Write a program that inputs a string that represents a binary number. The string can contain only 0s and 1s and no other characters, not even spaces. Validate that the entered number meets these requirements. If it does not, display an error message. If it is a valid binary number, determine the number of 1s that it contains. If it has exactly two 1s, display "Accepted". Otherwise, display "Rejected". All input and output should be from the console.

Examples of invalid binary numbers:
abc
10102011
10101FF
0000 1111 (note: contains a space)

Examples of valid, rejected binary numbers:
00000000
1111
01110000001

Examples of valid, accepted binary numbers:
1000001
1100

Your program will only test one input for each run of the program. Testing each of the test cases requires a separate run of your program for each one.

The following 3 test runs illustrate the format of the program's console input and output:

Enter a binary number > abc
Invalid binary number.

Enter a binary number > 01110000001
Rejected

Enter a binary number > 1000001
Accepted

Make sure you study the Final Project Guidance document.

Course Project Guidance
=======================

Getting the input
-----------------
Use the Scanner class nextLine method to input the binary number as a String.

Use the String charAt() method in a "for" loop that varies the index of the
character being examined. If your loop control variable is "i", then you will
use charAt(i) in the loop body to be able to examine the character at position "i".
As the loop progresses, you are able to get each character one-by-one. The
characters in a String are indexed from 0 to 1 less than the number of characters
in the String. The number of characters in the String can be determined by using
the String length() method.

Suppose you named the input String sInput. Then your "for" loop header would look like:
  for (int i = 0; i <= sInput.length() - 1; i++)

Note that charAt() returns a character as type "char". For comparison, remember that
character literals are enclosed in single quotation marks, like this: '1'.

Error message
-------------
When an invalid string is detected, display an error message, and then use a "return"
statement to exit from the main method (ending the program).

Purpose of "for" loop
---------------------
You must think about and understand the purpose of your "for" loop.
Don't try to fit your entire program into it.

For example, the "for" loop could count the number of invalid characters
(anything other than a '0' or a '1') and also it could count the number of
'1's it found.

Then, after the "for" loop is finished, that is after its closing brace, you
could have other code with "if" and/or "else" statements to decide what to output.

Of course, that means any variables you use in your post-"for" loop code must
be declared prior to the start of the "for" loop so they will still be in scope
after it finishes.

Answer 1

import java.util.Scanner;

public class ValidBinaryNumber {

   public static void main(String[] args) {

       // TODO Auto-generated method stub

      

       Scanner in = new Scanner(System.in);

       System.out.print("Enter a binary number >");

       String sInput = in.nextLine();

       boolean flag = false;

       int count = 0;

       for (int i = 0; i <= sInput.length() - 1; i++){

           if(sInput.charAt(i) == '0' || sInput.charAt(i) == '1' ){

               if(sInput.charAt(i) == '1')

                   ++count;

                 

           }else{

               System.out.println("Invalid binary number.");

               flag= true;

               break;

           }

             

       }

       if(!flag){

           if(count==2)

               System.out.println("Accepted");

           else

               System.out.println("Rejected");

          

       }

   }

}
======================================================================================

See The Output




Thanks, let me know if there is any concern.



See The Output