How to detect special characters in an edit text and display a Toast in response (Android)?

Question

An apology for my bad English, I\'m using google translate.

I\'m creating an activity in which users must create a new profile. I put a limit to edit text of 15 char

Answer 1

If you want to pick up the special chars and support more than just the very resrictive set of English alpha bet and numbers:

String edit_text_name = YourEditTextName.getText().toString();

Pattern regex = Pattern.compile("[$&+,:;=\\\\?@#|/'<>.^*()%!-]");

if (regex.matcher(edit_text_name).find()) {
        Log.d(TAG, "SPECIAL CHARS FOUND");
        //handle your action here toast message/ snackbar or something else
        return;
}

Answer 2

As I can´t comment on other posts, I will complement the most voted answer with a tip for a more fashion visual resolution.

First, pass the Edittext (etNombre) data to a String variable. Ex: String nombre = etNombre.getText().toString();

Then, use an if to verify:

if (!nombre.matches("[a-zA-Z.? ]*")) {

    etNombre.setError("Your message here");

}

this solution will set an "!" icon on the Edittext and it's much better than a Toast because the message is pointing the user to the error.

Answer 3

You can use:

string.matches("[a-zA-Z.? ]*")

That will evaluate to true if every character in the string is either a lowercase letter a-z, an uppercase letter A-Z, a period, a question mark, or a space.

like:

public void Click(View v) {
        if (v.getId() == R.id.button1) {
            String nombre = textMessage.getText().toString();
            if (nombre.length() == 0) {

                // Creamos el aviso
                Toast aviso = Toast.makeText(getApplicationContext(),
                        "Por favor introduce un nombre de Usuario",
                        Toast.LENGTH_LONG);
                aviso.show();

            } else if (!nombre.matches("[a-zA-Z.? ]*")) {
                Toast aviso = Toast
                        .makeText(
                                getApplicationContext(),
                                "No son permitidos los espacios ni los caracteres especiales",
                                Toast.LENGTH_LONG);
                aviso.show();

            } else {

                // Do what ever you want
            }

        }
    }

for allow a-z, A-Z, 0-9 use "[a-zA-Z0-9.? ]*"

Answer 4

You shoud go for Android Saripaar, a very light weight and simple API for android. In your case, you can do following stuff on you EditText instence...

@TextRule(order = 1, minLength = 15, message = "Enter atleast 15 characters.")
@Regex(order = 2, pattern = "[\\W+]", message = "Special characters are not allowed.")
private TextView yourEditText;

using this api will lead you to have more contorls on you validation process in proper way. you can also use [^a-zA-Z0-9] instead of [\\W+] as your reguler expression pattern.

Hope this helps..:)

Answer 5

use the the following line in edittext in xml file so that it only enters the alphabets and numbers;

 android:digits="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

If you need dynamic response use textwatcher for your edittext;

   yourEditText.addTextChangedListener(new TextWatcher() {

      public void afterTextChanged(Editable s) {

       // Here you need to check special character, if found then show error message

      if (s.toString().contains("%"))
      {
           // Display error message
      }

      public void beforeTextChanged(CharSequence s, int start, int count, int after) {}

      public void onTextChanged(CharSequence s, int start, int before, int count) {}
   });

Answer 6

Use:

public void click (View view) {

    if (edittext.matcher(abcd).find ()) {
       Toast.maketext(this, "abcd Found", TOAST.LENGTH_LONG).show ();
    }

}