how check if String has Full width character in java

Question

Can anyone suggest me how to check if a String contains full width characters in Java? Characters having full width are special characters.

Full width characters in String:

ａｂｃ＠ｇｍａｉｌ.ｃｏｍ

Half width characters in String:

[email protected]

Answer 1

I'm not sure if you are looking for any or all, so here are functions for both:

public static boolean isAllFullWidth(String str) {
    for (char c : str.toCharArray())
      if ((c & 0xff00) != 0xff00)
        return false;
    return true;
}

public static boolean areAnyFullWidth(String str) {
    for (char c : str.toCharArray())
      if ((c & 0xff00) == 0xff00)
        return true;
    return false;
}

As for your half width '.' and possible '_'. Strip them out first with a replace maybe:

String str="ａｂｃ＠ｇｍａｉｌ.ｃｏｍ";

if (isAllFullWidth(str.replaceAll("[._]","")))
  //then apart from . and _, they are all full width

Regex

Alternatively if you want to use a regex to test, then this is the actual character range for full width:

[\uFF01-\uFF5E]

So the method then looks like:

public static boolean isAllFullWidth(String str) {
    return str.matches("[\\uff01-\\uff5E]*");
}

You can add your other characters to it and so not need to strip them:

public static boolean isValidFullWidthEmail(String str) {
    return str.matches("[\\uff01-\\uff5E._]*");
}