Allow only upper case letters in EditText

Android has InputFilter for this, as you can see in official documentation . This is done by setting the filter using the setFilters() method of your EditText .

Ex:

editText.setFilters(new InputFilter[] {new InputFilter.AllCaps()});

If you put android:inputType="textCapCharacters" in the XML it will prioritize the uppercase letter, but the user may change depending on the device, so I suggest you tell him when to input the input data like this:

String algumaString = seuEdittext.getText().toString().toUpperCase();

EditText has a property called setInputType that receives an int value of the InputType class where you can programmatically change the user's input while typing, but I think it is not possible to only limit characters because depending on the device keyboard it is possible for the user click on the symbol button and select a number for example.