I have found many bugs in the Android's InputFilter, I am not sure if those are bugs or intended to be so. But definitely it did not meet my requirements. So I chose to use TextWatcher instead of InputFilter

private String newStr = "";

myEditText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // Do nothing
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            String str = s.toString();
            if (str.isEmpty()) {
                myEditText.append(newStr);
                newStr = "";
            } else if (!str.equals(newStr)) {
                newStr = str.replaceAll("[^A-Z0-9]", "");
                myEditText.setText("");
            }
        }

        @Override
        public void afterTextChanged(Editable s) {
            // Do nothing
        }
    });

The above code does not allow users to type any special symbol into your EditText. Only capital alphanumeric characters are allowed.

I have found many bugs in the Android's InputFilter, I am not sure if those are bugs or intended to be so. But definitely it did not meet my requirements. So I chose to use TextWatcher instead of InputFilter

private String newStr = "";

myEditText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // Do nothing
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            String str = s.toString();
            if (str.isEmpty()) {
                myEditText.append(newStr);
                newStr = "";
            } else if (!str.equals(newStr)) {
                // Replace the regex as per requirement
                newStr = str.replaceAll("[^A-Z0-9]", "");
                myEditText.setText("");
            }
        }

        @Override
        public void afterTextChanged(Editable s) {
            // Do nothing
        }
    });

The above code does not allow users to type any special symbol into your EditText. Only capital alphanumeric characters are allowed.