ET.addTextChangedListener(new PhoneNumberFormattingTextWatcher() {
        //we need to know if the user is erasing or inputing some new character
        private boolean backspacingFlag = false;
        //we need to block the :afterTextChanges method to be called again after we just replaced the EditText text
        private boolean editedFlag = false;
        //we need to mark the cursor position and restore it after the edition
        private int cursorComplement;

        @Override
        public void beforeTextChanged(CharSequence s,int start,int count,int after) {
            //we store the cursor local relative to the end of the string in the EditText before the edition
            cursorComplement = s.length()-ET.getSelectionStart();
            //we check if the user ir inputing or erasing a character
            if (count > after) {
                backspacingFlag = true;
            } else {
                backspacingFlag = false;
            }
        }

        @Override
        public void onTextChanged(CharSequence s,int before,int count) {
            // nothing to do here =D
        }

        @Override
        public void afterTextChanged(Editable s) {
            String string = s.toString();
            //what matters are the phone digits beneath the mask,so we always work with a raw string with only digits
            String phone = string.replaceAll("[^\\d]","");

            //if the text was just edited,:afterTextChanged is called another time... so we need to verify the flag of edition
            //if the flag is false,this is a original user-typed entry. so we go on and do some magic
            if (!editedFlag) {

                //we start verifying the worst case,many characters mask need to be added
                //example: 999999999 <- 6+ digits already typed
                // masked: (999) 999-999
                if (phone.length() >= 6 && !backspacingFlag) {
                    //we will edit. next call on this textWatcher will be ignored
                    editedFlag = true;
                    //here is the core. we substring the raw digits and add the mask as convenient
                    String ans = "(" + phone.substring(0,3) + ") " + phone.substring(3,6) + "-" + phone.substring(6);
                    ET.setText(ans);
                    //we deliver the cursor to its original position relative to the end of the string
                    ET.setSelection(ET.getText().length()-cursorComplement);

                //we end at the most simple case,when just one character mask is needed
                //example: 99999 <- 3+ digits already typed
                // masked: (999) 99
                } else if (phone.length() >= 3 && !backspacingFlag) {
                    editedFlag = true;
                    String ans = "(" +phone.substring(0,3) + ") " + phone.substring(3);
                    ET.setText(ans);
                    ET.setSelection(ET.getText().length()-cursorComplement);
                }
            // We just edited the field,ignoring this cicle of the watcher and getting ready for the next
            } else {
                editedFlag = false;
            }
        }
    });

确保将XML中的EditText Lenght限制为14个字符

<EditText
    android:id="@+id/editText_phone"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="phone"
    android:lines="1"
    android:maxLength="14"/>