Meaning of 0_0 in Java 7 [duplicate]

Answer 1

In Java 7 you can add underscores to increase the readability of number literals:

int oldMillion = 1000000;
int newMillion = 1_000_000;

It's especially useful with binary data:

byte oldMax = 0b01111111;
byte newMax = 0b0111_1111;