Error in simple binary-checking --- Sample Run.

[Chris]

Oops. Just as a follow-up. This is what the op looks like when i'm running my code:
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X:\Docs\School\NEU\Java\hw3>java Solution
Input a binary number: -1
Input must be >= 0.

Input a binary number: 1121
0

X:\Docs\School\NEU\Java\hw3>javac Solution.java

X:\Docs\School\NEU\Java\hw3>java Solution
Input a binary number: -1
Input must be >= 0.

Input a binary number: 1121
Input must be a Binary number.

Input a binary number: 1100
0

X:\Docs\School\NEU\Java\hw3>java Solution
Input a binary number: 1100
1100

X:\Docs\School\NEU\Java\hw3>