how to use replace function in java for case insensitive character value

Question

I am writing a java program in which a user enters a series of words that changes every 'p' to a 'b' in the sentence (case insensitive) and displays the output.

I try to use replace function but it is not case insensitive

String result = s.replace('p', 'b');

I expect the output boliticians bromised , but the actual outputs is Politicians bromised .

Answer 1

replace is case sensitive only.

There is no "simple" way to do this: you could do two replacements, but that constructs an intermediate string.

String result = s.replace('p', 'b').replace('P', 'B');

I would do this by iterating the character array:

char[] cs = s.toCharArray();
for (int i = 0; i < cs.length; ++i) {
  switch (cs[i]) {
    case 'p': cs[i] = 'b'; break;
    case 'P': cs[i] = 'B'; break;
  }
}
String result = new String(cs);

If you wanted to write a method to do this for non-hardcoded letters, you could do it like:

String method(String s, char from, char to) {
  char ucFrom = Character.toUpperCase(from);  // Careful with locale.
  char ucTo = Character.toUpperCase(to);

  char[] cs = s.toCharArray();
  for (int i = 0; i < cs.length; ++i) {
    if (cs[i] == from) { cs[i] = to; }
    else if (cs[i] == ucFrom) { cs[i] = ucTo; }
  }
  return new String(cs);
}

Answer 2

您可以使用正则表达式进行操作，请参阅问答- 如何在Java中替换不区分大小写的文字子字符串，也可以对p和P两次使用replace

Answer 3

您可以改用replaceAll以便使用正则表达式：

String result = s.replaceAll("[pP]", "b");