# Java Convert Binary to Decimal

To convert a binary number to a decimal number in Java, you can use the `parseInt()` method from the `Integer` class, specifying that the number is in base 2 (binary). Here’s an example:

```String binaryString = "110101";
int decimal = Integer.parseInt(binaryString, 2);
System.out.println(decimal);
```

In this example, the binary string `"110101"` is converted to the decimal value `53`. The `parseInt()` method takes two arguments: the first argument is the string to be parsed, and the second argument is the base of the number being parsed (in this case, `2` for binary).

Note that the input string must be a valid binary number, containing only `0` and `1` characters. If the string contains any other characters, a `NumberFormatException` will be thrown.

### Java Binary to Decimal conversion: Integer.parseInt()

Yes, the `Integer.parseInt()` method can be used in Java to convert a binary string to a decimal integer.

Here’s an example:

```String binaryString = "101010";
int decimalValue = Integer.parseInt(binaryString, 2);
System.out.println("Binary " + binaryString + " is equal to decimal " + decimalValue);
```

In this example, the binary string `"101010"` is converted to the decimal integer value `42`. The second argument to `Integer.parseInt()` is the radix, which is set to `2` to indicate that the string represents a binary value.

Note that the binary string must only contain the characters `0` and `1`. If any other character is present, an exception will be thrown.

### Java Binary to Decimal conversion: Custom Logic

If you prefer not to use the `Integer.parseInt()` method and want to implement your own logic to convert a binary string to a decimal integer in Java, you can follow these steps:

1. Initialize a variable to store the decimal value and set it to `0`.
2. Loop through each character of the binary string from right to left.
3. For each character, check if it is equal to `'1'`. If it is, add `2^i` to the decimal value, where `i` is the position of the character (counting from right to left).
4. After looping through all the characters, the decimal value is now calculated.

Here’s an example implementation:

```String binaryString = "101010";
int decimalValue = 0;
int position = 0;
for (int i = binaryString.length() - 1; i >= 0; i--) {
if (binaryString.charAt(i) == '1') {
decimalValue += Math.pow(2, position);
}
position++;
}
System.out.println("Binary " + binaryString + " is equal to decimal " + decimalValue);
```

In this example, the binary string `"101010"` is converted to the decimal integer value `42`. The loop starts from the rightmost character of the string and loops through each character, incrementing the `position` variable for each iteration. If the character is equal to `'1'`, the decimal value is updated by adding `2^position` to it. Finally, the decimal value is printed.

Note that this implementation assumes that the input binary string is valid, containing only the characters `'0'` and `'1'`.