我可以使用具有重叠值集的 BindingAdapter 吗？

Question

假设我有这个带有方法的视图模型：

public int getValueA() {
    return a;
}

public int getValueB() {
    return b;
}

@BindingAdapter("valueA")
public void setupSomething(View view, int valueA) {
    // do something with a
}

@BindingAdapter({"valueA", "valueB"})
public void setupSomethingElse(View view, int valueA, int valueB) {
    // do something with a and b
}

然后我将其绑定到一个视图：

<View
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    bind:valueA="@{viewmodel.valueA}"
    bind:valueB="@{viewmodel.valueB}"/>

如何调用这两个 BindingAdapter 方法？现在数据绑定只是调用后者。我想我可以从 setSomethingElse 中调用 setSomething 但这对我来说有点可疑（并且部分地破坏了数据绑定的目的）。

Answer 1

这就像你在暗示自己：你需要从 setupSomethingElse 调用 setupSomething()。这样做很好，数据绑定是如何工作的。 只有最合适的 @BindingAdapter 才会用于您的属性。

或者，您可以使用 @BindingAdapter 的 requireAll() 字段。但这只有在您可以为您的值处理 Java 默认值（在您的情况下为 0）时才可行。

Whether every attribute must be assigned a binding expression or if some can be absent. When this is false, the BindingAdapter will be called when at least one associated attribute has a binding expression. The attributes for which there was no binding expression (even a normal XML value) will cause the associated parameter receive the Java default value. Care must be taken to ensure that a default value is not confused with a valid XML value.

@BindingAdapter({"valueA", "valueB"}, requireAll = false)
public void setupSomethingElse(View view, int valueA, int valueB) {
    if (valueA != 0) {
        // do something with a
        if (valueB != 0) {
            // do something with a and b
        }
    }
}

所以您不再需要 setupSomething()。但我个人更喜欢第一种方法。

我可以使用具有重叠值集的 BindingAdapter 吗？

Can I have BindingAdapters with overlapping value sets?

android

android-databinding