Android双向数据绑定，textview不更新 [英] Android two-way databinding, textview not updating

问题描述

我正在尝试将MVVM模式与android数据绑定一起使用. 我有一个edittext和一个textview，当我通过一个带有LocationType模型对象的observablefield绑定到模型时，在edittext字段中键入内容时应该显示相同的文本.

I am trying to use MVVM pattern with android databinding. I have an edittext and a textview that should show the same text when I type in the edittext field by binding to the model via the observablefield with a LocationType model object.

从测试开始，按预期，当我启动应用程序时，两个字段都设置为"hello". 但是，当我在edittextfield中键入内容时，textview不会更新，即使很难调试，模型对象也能正确更新.

From testing both fields are set to "hello" when I start the app, as expected. But when I type in the edittextfield the textview does not update, even tough the model object gets updated correctly as can be seen with by debug.

当我使用时:

observablefield<String>

使用模型拖放并设置为一些文本，然后更新xml以使用此字段.它按预期工作.

drop using the model and just set to some text and update the xml to use this field. It works as intended.

型号:

public class LocationType {
private String locationType;

public String getLocationType() {
   return locationType;
}

public void setLocationType(String locationType) {
  this.locationType = locationType;

 }
}

模型视图:

public class LocationTypeViewModel extends BaseObservable {
  @Bindable
  private    ObservableField<LocationType> locationTypeObservableField = new ObservableField<>();
  private Context context;
  LocationType locationType;

  public LocationTypeViewModel(Context context) {
    this.context = context;

    locationType = new LocationType();
    locationType.setLocationType("Hello");
    locationTypeObservableField.set(locationType);


  }

  public ObservableField<LocationType> getLocationTypeObservableField() {
    Log.d("CALLED GET", locationType.getLocationType());
    return locationTypeObservableField;
  }


}    

XML:

<layout xmlns:app="http://schemas.android.com/apk/res-auto">

<data>

    <import type="android.view.View"/>

    <variable
        name="viewModel"
        type="fragment.LocationType.viewmodel.LocationTypeViewModel"/>
</data>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical">


    <EditText
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="@{viewModel.locationTypeObservableField.locationType}"
        android:id="@+id/edittext1"/>

    <TextView
        android:layout_below="@+id/edittext1"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text="@{viewModel.locationTypeObservableField.locationType}"
        android:id="@+id/text"
        />




</RelativeLayout>
</layout>

推荐答案

android:text ="@ = {viewModel.locationTypeObservableField.locationType}"

android:text="@={viewModel.locationTypeObservableField.locationType}"

您忘了添加"=".检查并将上面的代码与您的代码进行比较.

You forgot to add "=" .check and compare above line with your code.

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