The decision string in Android must contain letters or numbers _android

The public static Boolean isletterdigit (String str) {
  Boolean isdigit = false;//defines a Boolean value that is used to indicate whether a numeric Boolean is included
     Isletter = false;//defines a Boolean value that indicates whether to include the letter for
     (int i=0; I
       if (Character.isdigit (Str.charat (i))) {   // Judge each character
         IsDigit = True
       using the method of judging numbers in the Char wrapper class if (Character.isletter (Str.charat (i))) {  //judge each character Isletter = True using the method of judging letters in the Char wrapper class
         ;
     String regex = "^[a-za-z0-9]+$";
    Boolean isright = IsDigit && isletter&&str.matches (regex);
 return isright;
 
 }

Android determines whether edittext input numbers, Chinese, or alphabetic methods

String txt = edinput.gettext (). toString ();

  Pattern p = pattern.compile ("[0-9]*"); 
   Matcher m = p.matcher (TXT); 
   if (M.matches ()) {
   Toast.maketext (main.this, "Enter a number", Toast.length_short). Show (); 
   P=pattern.compile ("[a-za-z]");
   M=p.matcher (TXT);
   if (M.matches ()) {
   Toast.maketext (main.this, "input is a letter", Toast.length_short). Show ();
   P=pattern.compile ("[\u4e00-\u9fa5]");
   M=p.matcher (TXT);
   if (M.matches ()) {
   Toast.maketext (main.this, "input is Kanji", toast.length_short). Show ();