How to get 0-padded binary representation of an integer in java?

I think this is a suboptimal solution, but you could do

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

There is no binary conversion built into the java.util.Formatter, I would advise you to either use String.replace to replace space character with zeros, as in:

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

Or implement your own logic to convert integers to binary representation with added left padding somewhere along the lines given in this so. Or if you really need to pass numbers to format, you can convert your binary representation to BigInteger and then format that with leading zeros, but this is very costly at runtime, as in:

String.format("%016d", new BigInteger(Integer.toBinaryString(1)))

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

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

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 )