Question

我在我的android项目中使用RecyclerView，它的性能真的很糟糕。根据答案here，我尝试将adapter.setHasStableIds(true);添加到代码中。运行时出现错误：

java.lang.IllegalStateException: Cannot change whether this adapter has stable IDs while the adapter has registered observers.

我的完整logCat如下；

09-22 22:22:23.634 1808-1808/com.revosleap.movielist E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.revosleap.movielist, PID: 1808
java.lang.IllegalStateException: Cannot change whether this adapter has stable IDs while the adapter has registered observers.
    at android.support.v7.widget.RecyclerView$Adapter.setHasStableIds(RecyclerView.java:6749)
    at com.revosleap.movielist.Utils.UrlUtils.GenreFetcher.getGenre(GenreFetcher.java:48)
    at com.revosleap.movielist.MainActivity$2.onItemSelected(MainActivity.java:221)
    at android.widget.AdapterView.fireOnSelected(AdapterView.java:1124)
    at android.widget.AdapterView.access$200(AdapterView.java:54)
    at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:1089)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:145)
    at android.app.ActivityThread.main(ActivityThread.java:5942)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195)

请问该如何解决？

Answer 1

在将适配器分配给recyclerview之前，必须将适配器的hasStableIds设置为true。

YourAdapter adapter = new YourAdapter();
adapter.setHasStableIds(true);
myRecyclerView.setAdapter(adapter);

Answer 2

作为recyclerView源代码：

    /**
     * Indicates whether each item in the data set can be represented with a unique identifier
     * of type {@link java.lang.Long}.
     *
     * @param hasStableIds Whether items in data set have unique identifiers or not.
     * @see #hasStableIds()
     * @see #getItemId(int)
     */
    public void setHasStableIds(boolean hasStableIds) {
        if (hasObservers()) {
            throw new IllegalStateException("Cannot change whether this adapter has "
                    + "stable IDs while the adapter has registered observers.");
        }
        mHasStableIds = hasStableIds;
    } .

因此您可以解决它。

    if (!adapter.hasObservers()) {
        adapter.setHasStableIds(true)
    }

Answer 3

您不能将adapter.setHasStableIds(true);与ObservableArrayList / ObservableFields一起使用

Answer 4

在我的情况下，这是因为我将setHasStableIds(true)放入了片段的onActivityCreated()中。 Fragment是我的应用程序的重点，因此它永远不会从后堆栈中弹出。

class LocalFragment: Fragment() {
    private val adapter = LocalAdapter()
 
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        adapter.setHasStableIds(true)
    }
}

这里的问题是，每次onActivityCreated()被导航到Fragment时都会被调用。但是，由于Fragment仍然存在于后堆栈中，因此private val adapter字段仍与先前调用其setStableIds(true)的对象相同。

class LocalFragment: Fragment() {
    private var adapter = LocalAdapter()
 
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        adapter = LocalAdapter() // Re-assign the adapter
        adapter.setHasStableIds(true)
    }
}

解决方法是每次切换到片段时重新分配RecyclerView.Adapter对象。

当适配器已注册观察者时，无法更改此适配器是否具有稳定的ID

4 个答案: