带有if语句的Flutter CrossAxisAlignment

Question

有时想将我的Expanded类与end对齐，有时甚至要与start对齐。如何将Expanded类与if语句对齐？

 new Expanded(
              child: new Column(
                crossAxisAlignment: CrossAxisAlignment.end,
                children: <Widget>[
                  new Text(defaultUserName, style: Theme.of(ctx).textTheme.subhead),
                  new Container(
                    margin: const EdgeInsets.only(top: 10.0,right: 10.0),
                    child: new Text(txt),
                  ),
                ],
              ),
            ),

Answer 1

使用方式：

crossAxisAlignment: _alignEnd ? CrossAxisAlignment.end : CrossAxisAlignment.start,