Why is 08 not a valid integer literal in Java?

Question

Why is 08 considered an out of range int but 07 and below are not?

Answer 1

Any number prefixed with a 0 is considered octal. Octal numbers can only use digits 0-7, just like decimal can use 0-9, and binary can use 0-1.

// octal to decimal
01  // 1
02  // 2
07  // 7
010 // 8
020 // 16

// octal to binary (excluding most significant bit)
01  // 1 
02  // 10
07  // 111
010 // 1000 
020 // 10000

There are 10 types of people, those who understand ternary, those who don't, and those who think this is a stupid joke.