标签:android data-binding android-databinding
我想使用数据绑定库更改工具栏标题.一切正常,除了BottomNavigationView的监听器,即我有一个错误:
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> java.lang.RuntimeException: Found data binding errors.
****/ data binding error ****msg:Could not resolve viewmodel::onNavigationClick as a listener.
file:D:\Replacements\app\src\main\res\layout\activity_main.xml
loc:85:40 - 85:67
****\ data binding error ****
我认为这是由用于关联xml属性的setter的错误名称引起的.在xml中,BottomNavigationView有app:onNavigationItemSelected,但是BottomNavigationView的setter是setOnNavigationItemSelectedListener,而不是setOnNavigationItemSelected.如果我是对的,解决方案是在Android documentation.但是我应该在哪里放这个注释?在哪个级别?
换句话说,我应该怎么做才能在ViewModel中使用代码来控制BottomNavigationView上的点击?
这是文件:
ActivityMain.java
public class ActivityMain extends AppCompatActivity {
private ActivityMainViewModel viewModel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Initiating ViewModel to Activity
viewModel = ViewModelProviders.of(this).get(ActivityMainViewModel.class);
// Initiating ContentView in Activity
setContentView(R.layout.activity_main);
// Initiating DataBinding for ContentView in Activity
ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
binding.setViewmodel(viewModel);
}
}
ActivityMainViewModel.java
public class ActivityMainViewModel extends ViewModel {
private MutableLiveData<String> toolbarTitle = new MutableLiveData<>();
public String getToolbarTitle() {
return toolbarTitle.getValue();
}
public void setToolbarTitle(String toolbarTitle) {
this.toolbarTitle.setValue(toolbarTitle);
}
public boolean onNavigationClick(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_1:
setToolbarTitle("title 1");
return true;
case R.id.navigation_2:
setToolbarTitle("title 2");
return true;
case R.id.navigation_3:
setToolbarTitle("title 3");
return true;
}
return false;
}
}
activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable name="viewmodel" type="com.example.example.viewmodel.ActivityMainViewModel"/>
</data>
<android.support.constraint.ConstraintLayout
...>
<android.support.design.widget.AppBarLayout
...>
<android.support.v7.widget.Toolbar
android:id="@+id/main_toolbar"
android:title="@{viewmodel.toolbarTitle}"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@color/new_blue_light"
android:minHeight="?attr/actionBarSize"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
</android.support.design.widget.AppBarLayout>
<FrameLayout
...>
...
</FrameLayout>
<android.support.design.widget.BottomNavigationView
android:id="@+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:itemIconTint="@drawable/navigation_color_state"
app:itemTextColor="@drawable/navigation_color_state"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="@menu/navigation"
app:onNavigationItemSelected="@{viewmodel::onNavigationClick}"
tools:layout_constraintBottom_creator="0"
tools:layout_constraintLeft_creator="0"
tools:layout_constraintRight_creator="0" />
</android.support.constraint.ConstraintLayout>
</layout>
唯一的,我尝试做的是创建自定义视图(应用程序运行,但它不会更改工具栏标题并发出警告:警告:属性应用程序的应用程序命名空间:onNavigationItemSelected将被忽略.):
@BindingMethods({
@BindingMethod(
type = BottomNavigationViewBinding.class,
attribute = "app:onNavigationItemSelected",
method = "setOnNavigationItemSelectedListener"
),
})
public class BottomNavigationViewBinding extends BottomNavigationView{
private OnNavigationItemSelectedListener mSelectedListener;
public BottomNavigationViewBinding(Context context) {
this(context, null);
}
public BottomNavigationViewBinding(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public BottomNavigationViewBinding(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public interface OnNavigationItemSelectedListener {
boolean onNavigationItemSelected(MenuItem item);
}
public void setOnNavigationItemSelectedListener(@Nullable OnNavigationItemSelectedListener listener) {
mSelectedListener = listener;
}
}
解决方法:
用这个替换你的NavigationItemViewBinding类,它将工作:
public class BottomNavigationViewBindingAdapter {
@BindingAdapter("onNavigationItemSelected")
public static void setOnNavigationItemSelectedListener(
BottomNavigationView view, OnNavigationItemSelectedListener listener) {
view.setOnNavigationItemSelectedListener(listener);
}
}
这个想法是你想使用自定义setter来合并监听器,这比重命名设置监听器的方法需要更多的工作.
https://developer.android.com/topic/libraries/data-binding/index.html#custom_setters
标签:android,data-binding,android-databinding 来源: https://codeday.me/bug/20190522/1153911.html
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