ohn.smith@gmail.com user.name@domain.com@@@
jOHN.sMITH@gMAIL.cOM uSER.nAME@dOMAIN.cOM@@@
package egtry.regex; import java.util.regex.Matcher; import java.util.regex.Pattern; public class MatchReplace { public static void main(String[] args) { String text="john.smith@gmail.com\nuser.name@domain.com@@@"; Pattern pat=Pattern.compile("(\\w+)"); StringBuffer buff=new StringBuffer(); int offset=0; Matcher m=pat.matcher(text); while(!m.hitEnd()) { if (m.find(offset)) { int fromIndex=m.start(); int endIndex=m.end(); buff.append(text.substring(offset,fromIndex)); buff.append(replace(m.group(1))); offset=m.end(); } } System.out.println(buff.toString()+text.substring(offset)); } public static String replace(String origin) { return origin.charAt(0)+origin.substring(1).toUpperCase(); } }