edtext的实时监听

editText.addTextChangedListener(new TextWatcher() {            @Override            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {            }            @Override            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {            }            @Override            public void afterTextChanged(Editable editable) {                if (editText.length() > 0) {                    editText.setBackgroundColor(Color.BLUE);                } else {                    editText.setBackgroundColor(Color.RED);                }            }        });