Validation allow only number and characters in edit text in android

Question

In my application I have to validate the EditText. It should only allow character, digits, underscores, and hyphens.

Here is my code:

edittext.addTextChangedListener(new TextWatcher() {                                              @Override     public void onTextChanged(CharSequence s, int start, int before, int count) {         // TODO Auto-generated method stub                                   }                                              @Override     public void beforeTextChanged(CharSequence s, int start, int count, int after) {         // TODO Auto-generated method stub     }                                              @Override     public void afterTextChanged(Editable s) {         // validation codes here                                          location_name=s.toString();         Toast.makeText(getApplicationContext(),location_name, Toast.LENGTH_SHORT).show();                                  if (location_name.matches(".*[^a-z^0-9].*")) {             location_name = location_name.replaceAll("[^a-z^0-9]", "");             s.append(location_name);             s.clear();             Toast.makeText(getApplicationContext(),"Only lowercase letters and numbers are allowed!",Toast.LENGTH_SHORT).show();         }                                        }  });                                           location.add(location_name); 

When I enter input into EditText, the application is force closed.

Answer 1

Instead of using your "manual" checking method, there is something very easy in Android:

InputFilter filter = new InputFilter() {      public CharSequence filter(CharSequence source, int start,                                int end, Spanned dest, int dstart, int dend) {           for (int i = start;i < end;i++) {              if (!Character.isLetterOrDigit(source.charAt(i)) &&                  !Character.toString(source.charAt(i)).equals("_") &&                  !Character.toString(source.charAt(i)).equals("-"))              {                  return "";              }          }          return null;      }  };   edittext.setFilters(new InputFilter[] { filter });  

Or another approach: set the allowed characters in the XML where you are creating your EditText:

<EditText    android:inputType="text"    android:digits="0,1,2,3,4,5,6,7,8,9,*,qwertzuiopasdfghjklyxcvbnm,_,-"    android:hint="Only letters, digits, _ and - allowed" />