十进制转为二进制/八进制/十六进制
private static final char[] chs = { '0', '1', '2', '3', '4', '5', '6', '7','8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };public static String toHexString(int x) {return convert(x, 4);}public static String toOctalString(int x) {return convert(x, 3);}public static String toBinaryString(int x) {return convert(x, 1);}private static String convert(int x, int shift) {int mask = (1 << shift) - 1;char[] result = new char[32];int pos = 32;do {result[--pos] = chs[x & mask];x >>>= shift;} while (x != 0);// 起始偏移位置：pos表示当前索引位置// 偏移数：32-pos表示最后一位索引位置-当前索引位置+1,即总长度-当前索引位置return new String(result, pos, 32 - pos);}System.out.println(toBinaryString(-23423));System.out.println(Integer.toBinaryString(-23423));System.out.println(toOctalString(21321));System.out.println(Integer.toOctalString(21321));System.out.println(toHexString(21321));System.out.println(Integer.toHexString(21321));