How to initailize byte array of 100 bytes in java with all 0's

A new byte array will automatically be initialized with all zeroes. You don't have to do anything.

The more general approach to initializing with other values, is to use the Arrays class.

import java.util.Arrays;

byte[] bytes = new byte[100];
Arrays.fill( bytes, (byte) 1 );

Simply create it as new byte[100] it will be initialized with 0 by default

byte [] arr = new byte[100] 

Each element has 0 by default.

You could find primitive default values here:

Data Type   Default Value
byte        0
short       0
int         0
long        0L
float       0.0f
double      0.0d
char        '\u0000'
boolean     false