Replace two characters of string with each other in Java

Question

I have a 32-bit long string of 0s and 1s. I just want this string to be flipped just like binary bits. That is, 0s are to be replaced with 1s and 1s with 0s. I tried doing this replacement with this code in Java:

String flippedBit = StringUtils.replaceEach(PadChar,
        new String[]{"0","1"}, new String[]{"1","0"}, false);

But I get this error:

The method replaceEach(String, String[], String[]) in the type StringUtils is not applicable for the arguments (String, String[], String[], boolean)

Again, I have to store this string in an Integer by first converting it into 32-bit binary.

So why are you adding the boolean? `StringUtils` doesn't like it when you add the boolean. — Makoto, Feb 16 '15 at 05:29

score 2 · Answer 1 · answered Feb 16 '15 at 05:33

I would iterate the bits of some int v and flip them like

String str = Integer.toBinaryString(v);
StringBuilder sb = new StringBuilder();
for (char ch : str.toCharArray()) {
    sb.append(ch == '1' ? '0' : '1');
}
return Integer.parseInt(sb.toString(), 2);

score 0 · Answer 2 · answered Feb 16 '15 at 05:42

0

Sounds like this official nuts & bolts tutorial provides exactly what you're after:

The unary bitwise complement operator "~" inverts a bit pattern; it can be applied to any of the integral types, making every "0" a "1" and every "1" a "0".

That is, assuming you're working with the actual bits (in which case this would save you converting to a String and back), and not a String to start with (in which case you're better off with @ElliottFrisch's answer.

answered Feb 16 '15 at 05:42

Amos M. Carpenter

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By the way, [this answer](http://stackoverflow.com/a/791340/983430) explains in detail how the `~` operator works. – Amos M. Carpenter Feb 16 '15 at 05:47

Replace two characters of string with each other in Java

2 Answers2