Android数据绑定:多次调用自定义绑定适配器时，生成的代码中缺少返回语句 [英] Android Data Binding: Missing return statement in generated code when calling custom binding adapter more than once

问题描述

我正在使用android数据绑定库和MVVM体系结构.在xml布局中，我定义了一个名为myModel的viewModel变量.布局中有几个TextInputEditText，我为此使用了以下自定义绑定适配器:

I am using the android data binding library and MVVM architecture. In the xml layout I define a variable named viewModel of type myViewModel. The layout has several TextInputEditText for which I used the following custom binding adapter:

//makes the drawable_right of the TextView clickable
@SuppressLint("ClickableViewAccessibility")
@BindingAdapter("onDrawableRightClick")
inline fun TextView.setOnDrawableRightClick(crossinline f: () -> Unit) {
    this.setOnTouchListener(View.OnTouchListener { _, event ->
        if (event.action == MotionEvent.ACTION_UP) {
            if (event.rawX >= this.right - this.paddingRight - this.compoundDrawables[DRAWABLE_RIGHT].bounds.width()) {
                f()
                return@OnTouchListener true
            }
        }
        false
    })
}

在布局中，我仅将app:onDrawableRightClick="@{() -> viewModel.doThing()}"添加到TextInputEditText之一，然后单击运行.一切正常，没问题.

In the layout I add app:onDrawableRightClick="@{() -> viewModel.doThing()}" to just one of the TextInputEditText and click run. Everything works, no problem.

现在我返回并将app:onDrawableRightClick="@{() -> viewModel.doOtherThing()}"添加到第二个TextInputEditText.这次编译失败，并显示error: missing return statement.

Now I go back and add app:onDrawableRightClick="@{() -> viewModel.doOtherThing()}" to the second TextInputEditText. This time compilation fails with error: missing return statement.

此代码块中的错误是在MyFragmentBindingImpl中(生成的):

The error is in MyFragmentBindingImpl (generated), in this block of code:

public final kotlin.Unit _internalCallbackInvoke(int sourceId ) {
    switch(sourceId) {
        case 1: {
            // localize variables for thread safety
            // viewModel
            com.example.MyViewModel viewModel = mViewModel;
            // viewModel != null
            boolean viewModelJavaLangObjectNull = false;

            viewModelJavaLangObjectNull = (viewModel) != (null);
            if (viewModelJavaLangObjectNull) {

                   viewModel.doOtherThing();
            }
            return null;
        }
        case 2: {
            // localize variables for thread safety
            // viewModel
            com.example.MyViewModel viewModel = mViewModel;
            // viewModel != null
            boolean viewModelJavaLangObjectNull = false;

            viewModelJavaLangObjectNull = (viewModel) != (null);
            if (viewModelJavaLangObjectNull) {

                viewModel.doThing();
            }
            return null;
        }  
    }
}

在开关之外既没有默认情况，也没有return语句.这会导致错误，但是我很确定在处理每种情况时都不需要使用默认大小写...总之，当我返回xml并删除其中一个侦听器绑定时，MyFragmentBindingImpl更改为:

There is neither a default case nor a return statement outside of the switch. This causes the error but I was pretty sure that the default case isn't necessary when every case is handled... Anyways, when I go back to xml and remove one of the listener bindings, MyFragmentBindingImpl changes to this:

public final kotlin.Unit _internalCallbackInvoke(int sourceId ) {
    // localize variables for thread safety
    // viewModel
    com.example.MyViewModel viewModel = mViewModel;
    // viewModel != null
    boolean viewModelJavaLangObjectNull = false;

    viewModelJavaLangObjectNull = (viewModel) != (null);
    if (viewModelJavaLangObjectNull) {

      viewModel.doThing();
    }
    return null;
}

编译器再次感到高兴，但是我需要多次使用绑定适配器.如何使库添加一个return语句?有解决方法吗?

The compiler is happy again, but I need to use the binding adapter more than once. How can I make the library add a return statement? Is there a workaround?

我正在使用Android Studio 3.4预览版.谢谢大家

I'm using Android Studio 3.4 Preview. Thanks all

推荐答案

@SuppressLint("ClickableViewAccessibility")
@BindingAdapter("onDrawableEndClick")
fun setOnDrawableEndClick(view: TextView, listener: OnCompoundDrawableClickListener?) {
    val padding = 10
    if (listener != null) {
        view.setOnTouchListener { _, event ->
            if (event.action == MotionEvent.ACTION_DOWN) {
                if (view.compoundDrawables[DRAWABLE_RIGHT] == null) return@setOnTouchListener false
                else if (event.rawX >= (view.right - view.compoundDrawables[DRAWABLE_RIGHT].bounds.width() - padding)) {
                    listener.onDrawableEnd()
                    return@setOnTouchListener true
                }
            }
            return@setOnTouchListener false
        }
    }
}

尝试这样的事情，我正在为侦听器(OnCompoundDrawableClickListener)使用自定义界面

try something like this i am using a custom interface for the listener(OnCompoundDrawableClickListener)

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