Question

我有一个这样布局的应用程序，mainactivity托管2个标签，附带片段，第一个片段有一个有效的回收者视图，我试图在人物向上滚动时添加视差效果或我不确定是否应该将它添加到片段的xml或mainactivity的xml中，我将它添加到mainactivity的xml中并将片段作为我的recyclerview包含，不用了说视差不起作用，现在应用程序没有打开，我现在得到一个NullPointerException但是我没有触及代码。请指出我正确的方向。

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>

MainActivity.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)

可在此处找到完整日志http://pastebin.com/4cPGTx2z

Answer 1

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>

这会在Fragments内为ViewPager提供视差效果。

确保添加：

机器人：fitsSystemWindows =＆＃34;真＆＃34;

AppBarLayout和CollapsingToolbarLayout的属性，以及Toolbar的此属性：

应用程式：layout_collapseMode =＆＃34;销＆＃34;

如果您想添加其他Fragment，可以像这样添加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>

折叠工具栏和片段

1 个答案: