String str= hostField.getText().trim();
String regexp="[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}";
Pattern p=Pattern.compile(regexp,Pattern.CASE_INSENSITIVE);
Matcher m= p.matcher(str);
String regexp="[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}";
Pattern p=Pattern.compile(regexp,Pattern.CASE_INSENSITIVE);
Matcher m= p.matcher(str);
Matcher m= p.matcher(str);
出现错误标志!