转换为十进制但不使用integer.parseInt（）方法

So this is my first programming course and I have an assignment to convert a binary number entered by the user to a decimal. And my binary number should be stored in a a string. And to check that all my digits are 1s and 0s I need to use a method to make sure it's valid and return true if the the number is correct and false otherwise. So I did a search and saw that everyone was using the So this is my first programming course and I ha