Вроде все работает, но не проходит проверку

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Не пойму, что не так... в методе toBinary подставляю разные входные значения hexNumber, все работает корректно, что же им не нравится.. Посмотрите, пожалуйста, свежим взглядом, а то уже долго мучаю задачу, может что очевидное не вижу

The public static toHex(String) method must convert the string representation of a binary number, received as an input parameter, from the binary numeral system to hexadecimal and return its string representation.
And conversely, the public static toBinary(String) method converts from the string representation of a hexadecimal number to the string representation of a binary number.

The methods only work with non-empty strings.
If the input parameter is an empty string or null, then both methods return an empty string.
If the input parameter of the toHex(String) method contains any character other than 0 or 1, then the method returns an empty string.
If the input parameter of the toBinary(String) method contains any character other than digits from 0 to 9 or lowercase Latin letters from a to f, then the method returns an empty string.

Your task is to implement these methods.

One algorithm for converting the string representation of a binary number to the string representation of a hexadecimal number is as follows:

We check the length of the string received in the input parameter. It must be a multiple of 4.
If this is not the case, then add the required number of 0s to the beginning of the string.
We take every four characters (bits) and check which hexadecimal character they correspond to.

For example:

the binary representation is "100111010000", where "1001" is "9", "1101" is "d", and "0000" - "0"
the hexadecimal representation is "9d0".

One algorithm for converting the string representation of a hexadecimal number to the string representationof a binary number is as follows:
We take each character and check which binary number (4 bits) it corresponds to.

For example:

the hexadecimal representation is "9d0", where "9" is "1001", "d" is "1101", and "0" is "0000"
the binary representation is "100111010000".

The main() method is not involved in testing.

Requirements:

The toHex(String) method needs to be implemented as outlined in the task conditions.
The toBinary(String) method needs to be implemented as outlined in the task conditions.
The Integer.toBinaryString(int) and Long.toBinaryString(int) methods cannot be used.
The Integer.toHexString(int) and Long.toHexString(int) methods cannot be used.
The Integer.parseInt(String, int) and Long.parseLong(String, int) methods cannot be used.
The Integer.toString(int, int) and Long.toString(long, int) methods cannot be used.
You cannot use a BigInteger object.
You cannot use a BigDecimal object.

package en.javarush.task.pro.task09.task0908; /* Binary to hexadecimal converter */ import java.util.Arrays; public class Solution { private static final String HEX = "0123456789abcdef"; public static void main(String[] args) { String binaryNumber = "100111010000"; System.out.println("Binary number " + binaryNumber + " is equal to hexadecimal number " + toHex(binaryNumber)); String hexNumber = "d2f"; System.out.println("Hexadecimal number " + hexNumber + " is equal to binary number " + toBinary(hexNumber)); } public static String toHex(String binaryNumber) { // Проверка входного параметра. Входной параметр должен быть кратным 4 if (binaryNumber == "" || binaryNumber == null) return ""; else { while (binaryNumber.length() % 4 != 0) { binaryNumber = "0" + binaryNumber; } // преобраование строки в массив символов char[] binaryNumberArray = binaryNumber.toCharArray(); String hexNumber = ""; // делаем выборку из четырех символов for (int i = 0; i < binaryNumberArray.length / 4; i++) { int decimalNumber = 0; char[] binarySmall = Arrays.copyOfRange(binaryNumberArray, i * 4, i * 4 + 4); for (int j = 0; j < binarySmall.length; j++) { String x = binarySmall[j] + ""; int res = Integer.parseInt(x); decimalNumber = decimalNumber + (int) (res * Math.pow(2, binarySmall.length - 1 - j)); } char hex = HEX.charAt(decimalNumber); String hexstr = hex + ""; hexNumber = hexNumber + hexstr; } return hexNumber; } } public static String toBinary(String hexNumber) { if (hexNumber == "" || hexNumber == null) return ""; else { char[] hexNumberArray = hexNumber.toCharArray(); String binaryNumber = ""; for (int i = 0; i < hexNumberArray.length; i++) { String hexNumberStr = hexNumberArray[i] + ""; int decimalNumber = HEX.indexOf(hexNumberStr); for (int j = 0; j < 4; j++) { if (decimalNumber >= Math.pow(2, 3 - j)) { binaryNumber = binaryNumber + "1"; decimalNumber = (int) (decimalNumber - Math.pow(2, 3 - j)); } else binaryNumber = binaryNumber + "0"; } } return binaryNumber; } } }

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Ksenia Volkova Java Developer at DXC

Master

22 January 2022, 15:14

Думаю, для hexNumber "1" результат должен быть "1"

Aglaya

Level 47

23 January 2022, 07:47

так, ну, я отредактировала.. убрала лишние нули, но все равно не проходит..(( вот кусок кода обновленный.. public static String toBinary(String hexNumber) { String binaryNumber = ""; if (hexNumber == "" || hexNumber == null) return ""; else { char[] hexNumberArray = hexNumber.toCharArray(); for (int i = 0; i < hexNumberArray.length; i++) { String hexNumberStr = hexNumberArray[i] + ""; int decimalNumber = HEX.indexOf(hexNumberStr); for (int j = 0; j < 4; j++) { if (decimalNumber >= Math.pow(2, 3 - j)) { binaryNumber = binaryNumber + "1"; decimalNumber = (int) (decimalNumber - Math.pow(2, 3 - j)); } else { if (i == 0) binaryNumber = binaryNumber + ""; else binaryNumber = binaryNumber + "0"; } } } } return binaryNumber; }

Никита

Level 31

Expert

23 January 2022, 15:12

не учли что заглавные буквы не должны учитываться, а точнее сразу выдавать 0

Ksenia Volkova Java Developer at DXC

Master

23 January 2022, 15:38

toBinary(2) - что выведет? или toBinary(4) ?