SwipeRefreshLayout 下拉异常分派输入事件和空指针异常答案

【问题标题】：Exception Dispatching Input Event and Null Pointer Exception on SwipeRefreshLayout Pull downSwipeRefreshLayout 下拉异常分派输入事件和空指针异常
【发布时间】：2014-06-19 03:18:03
【问题描述】：

我有一个滑动来刷新布局（android.support.v4 修订版 19.1 的一部分），当我在布局上向下滑动时，我可以到达顶部已满的位置，但向下滑动会导致应用程序崩溃，并且 logcat 指向我的代码中没有特定的行。由于 SwipeRefreshLayout 才几个月大，因此互联网上没有很多信息可以帮助我找出问题所在。在我无法将支持 v4 修订版 19.1 添加到我的构建路径之前，但我很确定我已经解决了这个问题。这是 logcat，以及我的 SwipeRefreshLayout 的布局文件和代码。以及应用崩溃时的屏幕截图。

06-18 23:09:31.527: E/InputEventReceiver(25459): Exception dispatching input event.
06-18 23:09:31.547: E/AndroidRuntime(25459): FATAL EXCEPTION: main
06-18 23:09:31.547: E/AndroidRuntime(25459): Process: com.bernard.beaconportal, PID: 25459
06-18 23:09:31.547: E/AndroidRuntime(25459): java.lang.NullPointerException
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.support.v4.widget.SwipeRefreshLayout.startRefresh(SwipeRefreshLayout.java:441)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.support.v4.widget.SwipeRefreshLayout.onTouchEvent(SwipeRefreshLayout.java:399)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.View.dispatchTouchEvent(View.java:7706)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2210)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1945)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2339)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1569)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.app.Activity.dispatchTouchEvent(Activity.java:2492)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2286)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.View.dispatchPointerEvent(View.java:7886)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3947)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3826)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3392)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3442)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3411)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3518)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3419)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3575)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3392)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3442)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3411)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3419)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3392)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5532)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5512)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5483)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5612)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:176)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:5585)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:5631)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
06-18 23:09:31.547: E/AndroidRuntime(25459):    at android.view.Choreographer.doCa

这是布局

<android.support.v4.widget.SwipeRefreshLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#ffffff"
    android:id="@+id/swipe" >

    <ListView
        android:id="@+id/listView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
         android:background="#ffffff">

    </ListView>
</android.support.v4.widget.SwipeRefreshLayout>

这里是处理 SwipeRefreshLayout 的代码

SwipeRefreshLayout swipeLayout; 


    public static final String KEY_HOMEWORK="homework";
    public static final String KEY_DESC="desc";

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){


         View swipe = inflater.inflate(R.layout.activity_main, container, false); 

         swipeLayout = (SwipeRefreshLayout) swipe.findViewById(R.id.swipe);

         swipeLayout.setEnabled(false);

    ListView lView = (ListView) swipe.findViewById(R.id.listView1);

    lView.setOnScrollListener(new AbsListView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(AbsListView absListView, int i) {

        }

        @Override
        public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (firstVisibleItem == 0)
                    swipeLayout.setEnabled(true);
                else
                    swipeLayout.setEnabled(false);
        }
    });


    return swipe;

    }

这里是它崩溃的截图，你可以看到它一直向下滑动，通常它会在此时触发一些东西。但随后它崩溃了。

【问题讨论】：

标签： android android-listview nullpointerexception android-support-library swiperefreshlayout

【解决方案1】：

您的OnRefreshListener 为空，或者您没有设置一个，或者在您的代码的某个点将其设置为空。

在SwipeRefreshLayout的源码中，特别是这个sn-p

 private void startRefresh() {
        removeCallbacks(mCancel);
        mReturnToStartPosition.run();
        setRefreshing(true);
        mListener.onRefresh();
    }

在第 441 行，mListener.onRefresh(); 引发 NullPointerException。

【讨论】：

【解决方案2】：

我想通了。由于此片段包含在视图分页器中，因此 SwipeRefreshLayout 会延续到视图分页器中的其他片段，但除非您向其中添加代码，否则其他片段会崩溃。真是愚蠢的错误。

【讨论】：

所以我的片段在浏览器中。所以我将我的代码从第一个片段添加到第二个片段中，这样它也会有 SwipeRefreshLayout 。这解决了它。
我在所有片段中使用相同的布局。它仍在崩溃。我把它放在 ActivityFragment 中，现在它工作正常。我认为获取 Activity 的上下文存在问题。