java 折叠工具栏和片段
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Collapsing Toolbar and Fragment
提问by the_islander
I have an app that is laid out like this, the mainactivity hosts 2 tabs with accompanied fragments, the first fragment has a recycler view that works, I'm trying to add the parallax effect as the person scrolls up or down, wasn't sure if I should add it to the fragment's xml or the mainactivity's xml, I added it to the mainactivity's xml and included the fragment as my recyclerview, needless to say that the parallax didn't work and now the app doesn't open and I get a NullPointerException now but I didn't touch the code.Please point me in the correct direction.
我有一个这样布局的应用程序，主要活动托管 2 个带有片段的选项卡，第一个片段有一个有效的回收器视图，我试图在人向上或向下滚动时添加视差效果，不是确定我是否应该将它添加到片段的 xml 或主要活动的 xml，我将它添加到主要活动的 xml 并将片段作为我的回收器视图包含在内，不用说视差不起作用，现在应用程序没有打开，我现在得到一个 NullPointerException 但我没有触及代码。请指出正确的方向。
XML Below
下面的 XML
frag1.xml
片段1.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>
MainActivity.xml
主活动.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>
crash log excerpt
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)
Full log can be found here http://pastebin.com/4cPGTx2z
完整日志可以在这里找到http://pastebin.com/4cPGTx2z
回答by AndyRoid
You want to set something up like this:
你想设置这样的东西：
<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>
This will give you a parallax effect with Fragmentsinside the ViewPager.
这会给你一个Fragments内部的视差效果ViewPager。
Make sure you add the:
确保添加：
android:fitsSystemWindows="true"
机器人：fitsSystemWindows =“真”
Attribute to both AppBarLayoutand CollapsingToolbarLayout, and this attribute to the Toolbar:
属性不仅可以AppBarLayout和CollapsingToolbarLayout，而这种属性的Toolbar：
app:layout_collapseMode="pin"
应用程序：layout_collapseMode="pin"
If you want to add another Fragmentyou can add a FrameLayoutlike so:
如果你想添加另一个，Fragment你可以添加一个FrameLayout像这样的：
<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>
