1:public class BinaryToDecimal {
2:	private String binaryString;
3:	private int dec;
4:	//private static char[] letters = binaryString.toCharArray();
5:	public BinaryToDecimal(){
6:		// this("0");
7:	}
8:	public BinaryToDecimal(String binaryString) throws BinaryException
9:	{
10:		for(int i = 0; i < binaryString.length(); i++){
11:			int b = Integer.parseInt(Character.toString(binaryString.charAt(i)));
12:			if (b != 0 && b != 1){
13:				throw new BinaryException("This is not a binary number: " + binaryString);
14:			}
15:		}
16:		this.binaryString = binaryString;
17:	}
18:	public int toDecimal(String binaryString) throws BinaryException{
19:		for(int i = 0; i < binaryString.length(); i++){
20:			
21:			if (binaryString.charAt(i) != '0' && binaryString.charAt(i) != '1'){
22:				throw new BinaryException("This is not a binary number: " + binaryString);
23:			}
24:			
25:		}
26:		for(int i = 0; i < binaryString.length(); i++){
27:			dec += Integer.parseInt(Character.toString(binaryString.charAt(i))) * (Math.pow(2, (binaryString.length() - 1 - i)));
28:		}
29:		return dec;
30:	}
31:	public String toDecimaltoString(){
32:		return "The decimal equivalent is: "+ dec;
33:	}
34:}