The output of System.out.printf ("%x", ...) is represented by a number of 16 bits, starting with 0x as a symbol, and the numbers from 0 to 15 are 0x0, 0x 1, 0x2, 0x3, 0x4, 0x5, 0x6 and 0x respectively.

Where a, b, c, d and e respectively represent 10,1,12, 13, 14 and 15. When 16 ends, we will enter a quota.

System.out.printf("%h ",...) is the binary of this number, which means that the output is all 1 and 0.