可扩展列表视图中的android:divider属性在Android 6.01中崩溃了我的应用程序

Question

我不明白为什么当可扩展列表视图在带有分隔符设置的对话框片段中膨胀时,我的应用程序崩溃了.它只发生在Android 6.0中.Android 4.2没问题.

expandablelistview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="@+id/filter_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@+id/scroll_layout"
    android:background="#fff"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <ExpandableListView
        android:id="@+id/expandable_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:divider="@color/primaryLight"
        android:dividerHeight="5dp"/>
</LinearLayout>

对话框片段的一部分:

@Override
public void onViewCreated(final View view, @Nullable Bundle savedInstanceState) {

    if(savedInstanceState == null) {

        final Context context = getActivity();

        Bundle bundle = getArguments();

        Map<String, List<FilterItem>> listCollection = (Map<String, List<FilterItem>>) bundle.getSerializable(DATA);

        List<String> groupList = (List<String>) bundle.getSerializable(GROUP);

        ExpandableListView expListView = (ExpandableListView) view.findViewById(R.id.expandable_list);

        final ExpandableListAdapter expListAdapter = new ExpandableListAdapter(context, groupList, listCollection);

        expListView.setAdapter(expListAdapter);

        expListView.expandGroup(0);

    }
}

我认为崩溃是由xml中的分隔符设置引起的.部分错误表示失败setBounds(android.graphics.Rect),所以我猜它与分隔符有关:

android:divider="@color/primaryLight"
android:dividerHeight="5dp"

如果删除这两行,则可以打开对话框片段.

日志:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.graphics.drawable.Drawable.setBounds(android.graphics.Rect)' on a null object reference
at android.widget.ExpandableListView.drawDivider(ExpandableListView.java:534)
at android.widget.ListView.dispatchDraw(ListView.java:3335)
at android.widget.ExpandableListView.dispatchDraw(ExpandableListView.java:351)
at android.view.View.draw(View.java:16187)
at android.widget.AbsListView.draw(AbsListView.java:4166)
at android.view.View.updateDisplayListIfDirty(View.java:15180)
at android.view.View.draw(View.java:15954)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.draw(View.java:16187)
at android.view.View.updateDisplayListIfDirty(View.java:15180)
at android.view.View.draw(View.java:15954)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.updateDisplayListIfDirty(View.java:15175)
at android.view.View.draw(View.java:15954)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.updateDisplayListIfDirty(View.java:15175)
at android.view.View.draw(View.java:15954)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.draw(View.java:16187)
at com.android.internal.policy.PhoneWindow$DecorView.draw(PhoneWindow.java:2690)
at android.view.View.updateDisplayListIfDirty(View.java:15180)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:281)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:287)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:322)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2623)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2442)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2075)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1115)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6023)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:606)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5422)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Answer 1

正如您可以看到ExpandableListView的源代码,您的代码崩溃:

@Override
    void drawDivider(Canvas canvas, Rect bounds, int childIndex) {
        int flatListPosition = childIndex + mFirstPosition;

        // Only proceed as possible child if the divider isn't above all items (if it is above
        // all items, then the item below it has to be a group)
        if (flatListPosition >= 0) {
            final int adjustedPosition = getFlatPositionForConnector(flatListPosition);
            PositionMetadata pos = mConnector.getUnflattenedPos(adjustedPosition);
            // If this item is a child, or it is a non-empty group that is expanded
            if ((pos.position.type == ExpandableListPosition.CHILD) || (pos.isExpanded() &&
                    pos.groupMetadata.lastChildFlPos != pos.groupMetadata.flPos)) {
                // These are the cases where we draw the child divider
                final Drawable divider = mChildDivider;
                divider.setBounds(bounds);
                divider.draw(canvas);
                pos.recycle();
                return;
            }
            pos.recycle();
        }

        // Otherwise draw the default divider
        super.drawDivider(canvas, bounds, flatListPosition);
    }

您的代码已崩溃,因为它divider为null,或者mChildDivider为null,

mChildDivder 以两种方式接受价值:

1-来自xml via:

a.getDrawable(com.android.internal.R.styleable.ExpandableListView_childDivider);

所以你可以设置:

android:childDivider="..."

2-通过代码:

public void setChildDivider(Drawable childDivider) {
        mChildDivider = childDivider;
    }

你必须使用其中一个来设置mChildDivider.