langref.org - java - Regex

Replace the first regex match in a string with a static string

Transform "Red Green Blue" into "R*d Green Blue" by replacing /e/ with "*"

java

String replaced = "Red Green Blue".replaceFirst("e", "*");

Replace all regex matches in a string with a static string

Transform "She sells sea shells" into "She X X shells" by replacing /se\w+/ with "X"

java

String replaced = text.replaceAll("se\\w+", "X");

Replace all regex matches in a string with a dynamic string

Transform "The {Quick} Brown {Fox}" into "The kciuQ Brown xoF" by reversing words in braces using the regex /\{(\w+)\}/.

java

Matcher m = Pattern.compile("\\{(\\w+)\\}").matcher("The {Quick} Brown {Fox}");
StringBuffer sb = new StringBuffer(32), rsb = new StringBuffer(8);

while (m.find())
{
rsb.replace(0, rsb.length(), m.group(1)); rsb.reverse(); m.appendReplacement(sb, rsb.toString());
}
m.appendTail(sb);