½øÖÆ

final int tenNum = 123456789;
// ת¶þ½øÖÆ
System.out.println(Integer.toBinaryString(tenNum));
// ת°Ë½øÖÆת
System.out.println(Integer.toOctalString(tenNum));
// תʮ½øÖÆ
System.out.println(Integer.toUnsignedString(tenNum));
// תʮÁù½øÖÆ
System.out.println(Integer.toHexString(tenNum));

    public static void main(String[] args) {
        final int tenNum = 123456789;
        // תʮ½øÖÆ
        System.out.print("\nת10½øÖÆ£º" + twoToTen(Integer.toBinaryString(tenNum)));
        System.out.print("\t" + eightToTen(Integer.toOctalString(tenNum)));
        System.out.println("\t" + sixteenToTen(Integer.toHexString(tenNum)));

        // Ê®½øÖÆת
        System.out.print("Ê®½øÖÆת£º" + tenToTwo(tenNum));
        System.out.print("\t" + tenToEight(tenNum));
        System.out.println("\t" + tenToSixTeen(tenNum));

        // ¶þ½øÖÆת
        System.out.print("¶þ½øÖÆת£º" + twoToEight(Integer.toBinaryString(tenNum)));
        System.out.println("\t" + twoToSixteen(Integer.toBinaryString(tenNum)));

        // ת¶þ½øÖÆ
        System.out.print("ת¶þ½øÖÆ£º" + eightToTwo(Integer.toOctalString(tenNum)));
        System.out.println("\t" + sixteenToTwo(Integer.toHexString(tenNum)));
    }

    /**
     * ¶þ½øÖÆתʮ½øÖÆ
     */
    public static int twoToTen(String num) {
        int result = 0;
        int i = 0;
        while (!num.isEmpty()) {
            // ¸öλ * 2^i
            result += (int) (Integer.parseInt(num.substring(num.length() - 1)) * Math.pow(2, i));
            num = num.substring(0, num.length() - 1);
            i++;
        }
        return result;
    }

    /**
     * °Ë½øÖÆתʮ½øÖÆ
     */
    public static int eightToTen(String num) {
        int result = 0;
        int i = 0;
        while (!num.isEmpty()) {
            // ¸öλ * 8^i
            result += (int) (Integer.parseInt(num.substring(num.length() - 1)) * Math.pow(8, i));
            num = num.substring(0, num.length() - 1);
            i++;
        }
        return result;
    }

    /**
     * Ê®Áù½øÖÆתʮ½øÖÆ
     */
    public static int sixteenToTen(String num) {
        int result = 0;
        int i = 0;
        String str;
        int number;
        while (!num.isEmpty()) {
            str = num.substring(num.length() - 1);
            switch (str) {
                case "A":
                case "a":
                    number = 10;
                    break;
                case "B":
                case "b":
                    number = 11;
                    break;
                case "C":
                case "c":
                    number = 12;
                    break;
                case "D":
                case "d":
                    number = 13;
                    break;
                case "E":
                case "e":
                    number = 14;
                    break;
                case "F":
                case "f":
                    number = 15;
                    break;
                default:
                    number = Integer.parseInt(str);
                    break;
            }
            // ¸öλ * 16^i
            result += (int) (number * Math.pow(16, i));
            num = num.substring(0, num.length() - 1);
            i++;
        }
        return result;
    }

    /**
     * Ê®½øÖÆת¶þ½øÖÆ
     */
    public static String tenToTwo(int num) {
        StringBuilder result = new StringBuilder();
        while (num != 0) {
            // ¸öλ
            result.append(num % 2);
            num /= 2;
        }
        return result.reverse().toString();
    }

    /**
     * Ê®½øÖÆת°Ë½øÖÆ
     */
    public static String tenToEight(int num) {
        StringBuilder result = new StringBuilder();
        while (num != 0) {
            // ¸öλ
            result.append(num % 8);
            num /= 8;
        }
        return result.reverse().toString();
    }

    /**
     * Ê®½øÖÆתʮÁù½øÖÆ
     */
    public static String tenToSixTeen(int num) {
        StringBuilder result = new StringBuilder();
        while (num != 0) {
            // ¸öλ
            switch (num % 16) {
                case 10:
                    result.append("A");
                    break;
                case 11:
                    result.append("B");
                    break;
                case 12:
                    result.append("C");
                    break;
                case 13:
                    result.append("D");
                    break;
                case 14:
                    result.append("E");
                    break;
                case 15:
                    result.append("F");
                    break;
                default:
                    result.append(num % 16);
                    break;
            }
            num /= 16;
        }
        return result.reverse().toString();
    }

    /**
     * ¶þ½øÖÆת°Ë½øÖÆ
     */
    public static String twoToEight(String num) {
        StringBuilder result = new StringBuilder();
        while (num.length() >= 3) {
            result.append(twoToTen(num.substring(num.length() - 3)));
            num = num.substring(0, num.length() - 3);
        }
        if (!num.isEmpty()) {
            result.append(twoToTen(num));
        }
        return result.reverse().toString();
    }

    /**
     * ¶þ½øÖÆתʮÁù½øÖÆ
     */
    public static String twoToSixteen(String num) {
        StringBuilder result = new StringBuilder();
        while (num.length() >= 4) {
            result.append(tenToSixTeen(twoToTen(num.substring(num.length() - 4))));
            num = num.substring(0, num.length() - 4);
        }
        if (!num.isEmpty()) {
            result.append(tenToSixTeen(twoToTen(num)));
        }
        return result.reverse().toString();
    }

    /**
     * °Ë½øÖÆת¶þ½øÖÆ
     */
    public static String eightToTwo(String num) {
        StringBuilder result = new StringBuilder();
        StringBuilder str;
        while (!num.isEmpty()) {
            str = new StringBuilder(tenToTwo(Integer.parseInt(String.valueOf(num.charAt(0)))));
            while (str.length() < 3) {
                str.insert(0, "0");
            }
            result.append(str);
            num = num.substring(1);
        }
        return result.toString();
    }

    /**
     * Ê®Áù½øÖÆת¶þ½øÖÆ
     */
    private static String sixteenToTwo(String num) {
        StringBuilder result = new StringBuilder();
        StringBuilder str;
        while (!num.isEmpty()) {
            str = new StringBuilder(tenToTwo(sixteenToTen(String.valueOf(num.charAt(0)))));
            while (str.length() < 4) {
                str.insert(0, "0");
            }
            result.append(str);
            num = num.substring(1);
        }
        return result.toString();
    }