Android - TextWatcher监听事件的使用

      mEditStatus.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

            }

            @Override
            public void afterTextChanged(Editable s) {
                int count = 140 - mEditStatus.length();
                mTextCount.setText(Integer.toString(count));
                mTextCount.setTextColor(Color.GREEN);
                if (count < 10)
                    mTextCount.setTextColor(Color.YELLOW);
                else if (count < 0)
                    mTextCount.setTextColor(Color.RED);
            }
        });