android - CoordinatorLayout 中的 NullPointerException onTouchEvent

Question

我的应用中出现此错误，原因不明。没有一行与我的代码相关，我真的不知道问题出在哪里以及如何解决。

E/AndroidRuntime: FATAL EXCEPTION: main
      Process: com.afranet.salesportal, PID: 20933
      java.lang.NullPointerException: Attempt to invoke virtual method 'float android.view.MotionEvent.getX()' on a null object reference
      at android.view.View.onTouchEvent(View.java:10608)
      at android.support.design.widget.CoordinatorLayout.onTouchEvent(CoordinatorLayout.java:449)
      at android.view.View.dispatchTouchEvent(View.java:9187)
      at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2644)
      at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2351)
      at android.support.v4.widget.DrawerLayout.cancelChildViewTouch(DrawerLayout.java:1668)
      at android.support.v4.widget.DrawerLayout$ViewDragCallback.peekDrawer(DrawerLayout.java:1916)
      at android.support.v4.widget.DrawerLayout$ViewDragCallback.access$000(DrawerLayout.java:1801)
      at android.support.v4.widget.DrawerLayout$ViewDragCallback$1.run(DrawerLayout.java:1807)
      at android.os.Handler.handleCallback(Handler.java:739)
      at android.os.Handler.dispatchMessage(Handler.java:95)
      at android.os.Looper.loop(Looper.java:145)
      at android.app.ActivityThread.main(ActivityThread.java:6917)
      at java.lang.reflect.Method.invoke(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:372)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)

这是我的布局:

activity_home.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorLightGrayBackground"
    android:layoutDirection="rtl"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_home"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@color/colorNavbarBackground"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_home"
        app:itemIconTint="@drawable/navigation_icon_color"
        app:itemTextColor="@drawable/navigation_icon_color"
        app:menu="@menu/activity_home_drawer" />

</android.support.v4.widget.DrawerLayout>

app_bar_home.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".activity.HomeActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize">

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="right"
                android:text="" />
        </android.support.v7.widget.Toolbar>


    </android.support.design.widget.AppBarLayout>

    <include
        layout="@layout/content_home"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="?attr/actionBarSize" />

    <!--android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_dialog_email"
        android:visibility="gone" /  !-->

</android.support.design.widget.CoordinatorLayout>

content_home.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/appbar"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".activity.HomeActivity"
    tools:showIn="@layout/app_bar_home">


</RelativeLayout>

onTouchEvent 方法中的 CoordinatorLayout 代码似乎有问题。

Answer 1

好像是a bug in Support Library com.android.support:design:23.0.0。我找到了解决问题的答案。

1- 更新支持库会自动解决问题。

2- 覆盖 Activity 中的 dispatchTouchEvent 方法将解决问题:

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    try {
        return super.dispatchTouchEvent(ev);
    } catch (Exception e) {
        return false;
    }
}

3- This answer也不错 :

ViewGroup appBarLayout = (ViewGroup) ret.findViewById(R.id.appbarlayout);
            for (int i = 0; i < appBarLayout.getChildCount(); i++) {
                View childView = appBarLayout.getChildAt(i);
                if (!childView.isClickable()) {
                    childView.setOnTouchListener(new View.OnTouchListener() {
                        @Override
                        public boolean onTouch(View view, MotionEvent motionEvent) {
                            return true;
                        }
                    });
                }
            }