Java 程序将二进制数转换为八进制数，反之亦然

class Main {
  public static void main(String[] args) {
    long binary = 101001;
    int octal = convertBinarytoOctal(binary);
    System.out.println(binary + " in binary = " + octal + " in octal");
  }
  public static int convertBinarytoOctal(long binaryNumber) {
    int octalNumber = 0, decimalNumber = 0, i = 0;
    while (binaryNumber != 0) {
      decimalNumber += (binaryNumber % 10) * Math.pow(2, i);
      ++i;
      binaryNumber /= 10;
    }
    i = 1;
    while (decimalNumber != 0) {
      octalNumber += (decimalNumber % 8) * i;
      decimalNumber /= 8;
      i *= 10;
    }
    return octalNumber;
  }
}

101001 in binary = 51 in octal

Binary To Decimal
1 * 25 + 0 * 24 + 1 * 23 + 0 * 22 + 0 * 21 + 1 * 20 = 41
Decimal to Octal
8 | 41
8 | 5 --1
8 | 0 --5
(51)

class Main {
  public static void main(String[] args) {
    int octal = 67;
    long binary = convertOctalToBinary(octal);
    System.out.println(octal + " in octal = " + binary + " in binary");
  }
  public static long convertOctalToBinary(int octalNumber) {
    int decimalNumber = 0, i = 0;
    long binaryNumber = 0;
    while (octalNumber != 0) {
      decimalNumber += (octalNumber % 10) * Math.pow(8, i);
      ++i;
      octalNumber /= 10;
    }
    i = 1;
    while (decimalNumber != 0) {
      binaryNumber += (decimalNumber % 2) * i;
      decimalNumber /= 2;
      i *= 10;
    }
    return binaryNumber;
  }
}

67 in octal = 110111 in binary

Octal To Decimal
6 * 81 + 7 * 80 = 55
Decimal to Binary
2 | 55
2 | 27--1
2 | 13--1
2 | 6 --1
2 | 3 --0
2 | 1 --1
2 | 0 --1
(110111)