try this func
static boolean isValidUTF16(String s) {
for (int i = 0; i < s.length(); i++) {
if (Character.isLowSurrogate(s.charAt(i)) && (i == 0 || !Character.isHighSurrogate(s.charAt(i - 1)))
|| Character.isHighSurrogate(s.charAt(i)) && (i == s.length() -1 || !Character.isLowSurrogate(s.charAt(i + 1)))) {
return false;
}
}
return true;
}
here's a test
public static void main(String args[]) {
System.out.println(isValidUTF16("\uDC00\uDBFF"));
System.out.println(isValidUTF16("\uDBFF\uDC00"));
}