Java asking for return statement for class

I have the following code:

public class BinaryDecoder{
public static void main(String[] args){
    String binNum = "110101"; 
    int res = 0;
    for (int i = 0;i<binNum.length();i++){
        //res += parseDigit(binNum.charAt(i),binNum);
    }
//  System.out.println(res);

}
public static int parseDigit(int index, String binNum){
    switch (binNum.charAt(index)){
        case 0:
        break;
        case 1:
        int val = (int) Math.pow(2,-index+binNum.length());
        return val;
        }
}

}

And I am getting the error: BinaryDecoder.java:30: error: missing return statement } ^

I may have interpreted this wrong, but why would my class BinaryDecode have or even need a return statement? Is there something else wrong with the code?

Note: I am fairly new in java, so sorry if there are any obvious errors in my code.