Question

我无法使数据绑定在BottomSheetDialog布局上正常工作。详细信息如下：

var的定义和设置：

private lateinit var myDrawerBinding: MyDrawerBinding

myDrawerBinding = MyDrawerBinding.bind(myDrawerContent) // crashes on this line

然后以这种方式设置并显示它（尽管它永远不会到达这一点）

myDrawerBinding.viewModel = theViewModel

val bottomSheet = BottomSheetDialog(context)
bottomSheet.setContentView(myDrawerBinding.myDrawerContent)
bottomSheet.show()

以下是XML布局的代码段（my_drawer.xml）：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

<data>
    <import type="android.view.View"/>
    <variable name="viewModel" type="path.to.my.viewModel"/>
</data>

<RelativeLayout
        android:id="@+id/myDrawerContent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="10dp">

    <View
            android:layout_width="50dp"
            android:layout_height="3dp"
            android:visibility="@{viewModel.shouldShowView() ? View.VISIBLE : View.GONE}"/>
....

当它调用上面的.bind（）方法时发生崩溃，并且错误是：

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.view.View.getTag()' on a null object reference

与我在同一Fragment中显示的单独的DrawerLayout相同的功能完全相同，但是由于某些原因，BottomSheetDialog布局出现问题。

Answer 1

最终找到了解决办法。我不得不将此视图与DrawerLayout稍有不同，尽管我感觉这种方法也可能适用于该视图。

这是绑定设置：

class Slider extends Component {
  constructor(props){
    super(props);
    this.state={
      active: 0,
      length: props.items.length
    }
  }

  next = e => {
    let nextImage = this.state.active+1;
    if(nextImage<this.state.length){
        this.setState({active: nextImage});
    }
  }

  prev = e => {
    let prevImage = this.state.active-1;
    if(prevImage>=0){
        this.setState({active: prevImage});
    }
  }

  goTo = ind => this.setState({active:ind});
render(){
  return (
    <div>
      <div className="slideshow-container">
        <div className="mySlides fade">
           <div className="numbertext">{this.state.active + 1} / {this.state.length}</div>
          <img src={this.props.items[this.state.active].img} height="300"/>
          <div className="text">{this.props.items[this.state.active].title}</div>
        </div>
        <a className="prev" onClick={this.prev} style={{backgroundColor:'#ccc', padding:'10px'}}>&#10094;</a>
        <a className="next" onClick={this.next}  style={{backgroundColor:'#ccc', padding:'10px', float:'right'}}>&#10095;</a>
      </div>
      <div className="dots">
        {this.props.items.map((n, i) => (
          <span
            key={n.id}
            className={`dot ${i === this.state.active ? 'active' : ''}`}
            onClick={()=>this.goTo(i)}
          ></span>
        ))}
      </div>
    </div>
  );
}
}

然后显示视图：

val myDrawerView = layoutInflater.inflate(R.layout.my_drawer, null)
val binding = MyDrawerBinding.inflate(layoutInflater, myDrawerView as ViewGroup, false)
binding.viewModel = theViewModel

现在就像魅力一样！

BottomSheetDialog布局上的数据绑定（崩溃）

1 个答案: