How to get 0-padded binary representation of an in

Question

for example, for 1, 2, 128, 256 the output can be (16 digits):

0000000000000001
0000000000000010
0000000010000000
0000000100000000

I tried

String.format("%16s", Integer.toBinaryString(1));

it puts spaces for left-padding:

`               1'

How to put 0s for padding. I couldn't find it in Formatter. Is there another way to do it?

Thanks in advance.

P.S. this post describes how to format integers with left 0-padding, but it is not for the binary representation.

Answer 1

You can use Apache Commons StringUtils. It offers methods for padding strings:

StringUtils.leftPad(Integer.toBinaryString(1), 16, '0');

Answer 2

Here a new answer for an old post.

To pad a binary value with leading zeros to a specific length, try this:

Integer.toBinaryString( (1 << len) | val ).substring( 1 )

If len = 4 and val = 1,

Integer.toBinaryString( (1 << len) | val )

returns the string "10001", then

"10001".substring( 1 )

discards the very first character. So we obtain what we want:

"0001"

If val is likely to be negative, rather try:

Integer.toBinaryString( (1 << len) | (val & ((1 << len) - 1)) ).substring( 1 )

Answer 3

I do not know "right" solution but I can suggest you a fast patch.

String.format("%16s", Integer.toBinaryString(1)).replace(" ", "0");

I have just tried it and saw that it works fine.