相关疑难解决方法(0)

我尝试将RecyclerView与RecyclerView.Adapter一起使用,但这里出了点问题.我在下面发布我的代码:

布局:

   <android.support.v7.widget.RecyclerView
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/topic_view"
    android:scrollbars="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

topic_tile.xml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="@dimen/tile_height">

    <com.makeramen.RoundedImageView
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/avatar"
        android:padding="16dp"
        app:riv_corner_radius="72dp"
        android:layout_height="72dp"
        android:layout_width="72dp"
        />

    <LinearLayout
        android:id="@+id/text_layout"
        android:orientation="vertical"
        android:paddingTop="@dimen/text_padding_top_and_bottom"
        android:paddingBottom="@dimen/text_padding_top_and_bottom"
        android:paddingRight="16dp"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:id="@+id/title"
            android:textSize="@dimen/primary_font"
            android:paddingLeft="@dimen/text_padding_left"
            android:textColor="#000000"
            android:text="Title"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
        <TextView
            android:id="@+id/author"
            android:textSize="@dimen/secondary_font"
            android:paddingLeft="@dimen/text_padding_left"
            android:text="author"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>
</RelativeLayout>

这是在 onCreate()

public class TitleListActivity extends ActionBarActivity {

    private RecyclerView topic_view;
    private RecyclerView.LayoutManager mLayoutManager;
    private TitlelistAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_title_list);

        .....

        topic_view = (RecyclerView)findViewById(R.id.topic_view); …

我正在尝试显示循环视图时遇到异常:

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.support.v7.widget.RecyclerView$LayoutManager.canScrollVertically()' on a null object reference
at android.support.v7.widget.RecyclerView.computeVerticalScrollRange(RecyclerView.java:1216)
    at android.view.View.onDrawScrollBars(View.java:13900)
    at android.view.View.draw(View.java:16275)
    at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:2440)
    at android.view.View.updateDisplayListIfDirty(View.java:15192)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.View.draw(View.java:15990)
    at android.view.ViewGroup.drawChild(ViewGroup.java:3708)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3502)
    at android.view.View.draw(View.java:16272)
    at android.view.View.updateDisplayListIfDirty(View.java:15192)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
    at android.view.View.updateDisplayListIfDirty(View.java:15152)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
    at android.view.View.updateDisplayListIfDirty(View.java:15152)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:362)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
    at android.view.View.updateDisplayListIfDirty(View.java:15152)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
    at android.view.View.updateDisplayListIfDirty(View.java:15152)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
    at android.view.View.updateDisplayListIfDirty(View.java:15152)
    at android.view.View.getDisplayList(View.java:15215)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692) …