java - how to get the binary values of the bytes stored in byte array

Question

i am working on a project that gets the data from the file into a byte array and adds "0" to that byte array until the length of the byte array is 224 bits. I was able to add zero's but i am unable to confirm that how many zero's are sufficient. So i want to print the file data in the byte array in binary format. Can anyone help me?

Answer 1

For each byte:

• cast to int (happens in the next step via automatic widening of byte to int)
• bitwise-AND with mask 255 to zero all but the last 8 bits
• bitwise-OR with 256 to set the 9th bit to one, making all values exactly 9 bits long
• invoke Integer.toBinaryString() to produce a 9-bit String
• invoke String#substring(1) to "delete" the leading "1", leaving exactly 8 binary characters (with leading zeroes, if any, intact)

Which as code is:

byte[] bytes = "377317abc".getBytes();
for (byte b : bytes) {
    System.out.println(Integer.toBinaryString(b & 255 | 256).substring(1));
}

Output of above code (always 8-bits wide):

11111111
00000000
11001111
00001001
01100001
01100010
01100011