Inverting bits of binary string java

Question

I want to invert the bits in binary string. For example String 000 should be inverted as 111 and 1101 as 0010. Can anybody help on this?

That is what ~ operator does. Did you search for 1's complement? — Rohit Jain
– Rohit Jain, Commented Mar 25, 2014 at 8:13

Joop Eggen · Accepted Answer · 2014-03-25 08:16:18Z

10

s = s.replace('0', '2').replace('1', '0').replace('2', '1');

answered Mar 25, 2014 at 8:16

Joop Eggen

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2 Comments

user3259851 Over a year ago

Yes this worked. If you don't mind Can explain me how does it work?

JGFMK Over a year ago

@user3259851 If swaps 0's for 2's - so that when 1's are replaced with 0's you still have the 2's to then convert to 0's,, You need the intermediate 2, otherwise after replacing 0's with 1's you'd have a string of all 1's!

Christian Tapia · Accepted Answer · 2014-03-25 08:17:19Z

3

One way: is using the replaceAll() method:

String s = "01010";

s = s.replaceAll("0", "x");
s = s.replaceAll("1", "0");
s = s.replaceAll("x", "1");

System.out.println(s);

Output:

Note:

This can be simplified chaining calls:

s = s.replaceAll("0", "x").replaceAll("1", "0").replaceAll("x", "1");

answered Mar 25, 2014 at 8:17

Christian Tapia

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Comments

Naveen Ramawat · Accepted Answer · 2014-03-25 08:19:26Z

1

Check this, Here input is intger but you could easily convert your string into int I hope it will not be big task.

int i= 100;
System.out.println(Integer.toBinaryString(~i));

answered Mar 25, 2014 at 8:19

Naveen Ramawat

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2 Comments

Peter Lawrey Over a year ago

That will drop leading 000s

Naveen Ramawat Over a year ago

depends on the requirement. I don't think leading 000 has any meaning.

Peter Lawrey · Accepted Answer · 2014-03-25 08:42:38Z

1

You can do this trick to swap 0 and 1

String s = "00011";
char[] chars = new char[s.length()];
for(int i = 0; i < s.length(); i++)
    chars[i] = (char) (s.charAt(i) ^ 1); // flip the bottom bit so 0=>1 and 1=>0
String flipped = new String(chars);
// flipped = "11100"

answered Mar 25, 2014 at 8:42

Peter Lawrey

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Comments

wumpz · Accepted Answer · 2014-03-25 09:05:39Z

1

Using Apache commons-lang library you got a handy method to achieve this:

StringUtils.replaceChars(mystr, "01", "10");

Basically it replaces characters with corresponding characters (correspondence by index).

This is the litte test program

import org.apache.commons.lang.StringUtils;

public class InvertString {
    public static void main(String[] args) {
        System.out.println(invert("0001011"));
        System.out.println(invert("000"));
        System.out.println(invert("1101"));
    }

    private static String invert(String string) {
        return StringUtils.replaceChars(string, "01", "10");
    }
}

and the output of it is

1110100
111
0010

answered Mar 25, 2014 at 9:05

wumpz

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