我有一个这样布局的应用程序,mainactivity 包含 2 个带有 fragment 的选项卡,第一个 fragment 有一个可用的回收 View ,我试图在用户向上或向下滚动时添加视差效果,不确定我是否应该将它添加到 fragment 的 xml 或 mainactivity 的 xml,我将它添加到 mainactivity 的 xml 并将 fragment 作为我的 recyclerview,不用说视差不起作用,现在应用程序不起作用打开,我现在得到一个 NullPointerException,但我没有触及代码。请指出正确的方向。
下面的 XML
frag1.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"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/my_recycler_view"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout>
主 Activity .xml
<android.support.design.widget.CoordinatorLayout
android:id="@+id/main_layout"
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"
tools:context=".MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_height="100dp"
android:layout_width="match_parent"
android:fitsSystemWindows="true"
>
<android.support.design.widget.CollapsingToolbarLayout
app:layout_scrollFlags="scroll|exitUntilCollapsed"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<ImageView
android:layout_height="match_parent"
android:layout_width="match_parent"
app:layout_collapseMode="parallax"
/>
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:background="@color/ColorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
app:layout_collapseMode="pin"/>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
<android.support.design.widget.TabLayout
android:id="@+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/toolbar"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:layout_scrollFlags="enterAlways"
/>
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_below="@id/tab_layout"
app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
崩溃日志摘录
07-08 19:43:54.671 2264-2264/com.example.dimple.test E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.dimple.test, PID: 2264
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView$LayoutManager.onMeasure(android.support.v7.widget.RecyclerView$Recycler, android.support.v7.widget.RecyclerView$State, int, int)' on a null object reference
at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:1764)
at android.view.View.measure(View.java:17430)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:727)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:463)
at android.view.View.measure(View.java:17430)
可以在这里找到完整的日志 http://pastebin.com/4cPGTx2z
最佳答案
你想这样设置:
<android.support.design.widget.CoordinatorLayout>
<android.support.design.widget.AppBarLayout>
<android.support.design.widget.CollapsingToolbarLayout
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<ImageView
app:layout_collapseMode="parallax"/>
<android.support.v7.widget.Toolbar />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<LinearLayout
app:layout_behavior="@string/appbar_scrolling_view_behavior" >
<android.support.design.widget.TabLayout />
<android.support.v4.view.ViewPager />
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
这将为您提供 ViewPager
内的 Fragments
的视差效果。
确保添加:
android:fitsSystemWindows="true"
AppBarLayout
和 CollapsingToolbarLayout
的属性,以及 Toolbar
的属性:
app:layout_collapseMode="pin"
如果你想添加另一个 Fragment
,你可以像这样添加一个 FrameLayout
:
<android.support.design.widget.CoordinatorLayout>
<android.support.design.widget.AppBarLayout>
<!-- CollapsingToolbarLayout -->
</android.support.design.widget.AppBarLayout>
<LinearLayout >
<android.support.design.widget.TabLayout />
<android.support.v4.view.ViewPager />
</LinearLayout>
<FrameLayout />
</android.support.design.widget.CoordinatorLayout>
关于java - 折叠工具栏和 fragment ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31302053/