对EditText监听，按钮点击

1

etBarCode.addTextChangedListener(watcher);

2

private TextWatcher watcher = 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 (editable.length() == 0) {
            btnConfirm.setEnabled(false);
        } else {
            btnConfirm.setEnabled(true);
        }

    }
};