Android之使用RecyclerView异常情况

痛定思痛。 2022-07-21 05:59 210阅读 0赞

今天在使用RecyclerView时遇到了一些异常情况，记录下。  
在布局中添加了RecyclerView，如下：

<android.support.v7.widget.RecyclerView
            android:id="@+id/hlv_hour_forecast"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1">
    
        </android.support.v7.widget.RecyclerView>

若在代码中无使用到RecyclerView（只是在layout上显示数据，还没绑定数据时），即没有在**onCreate()方法**中添加如下的代码

hlv = (RecyclerView) view.findViewById(R.id.hlv_hour_forecast);
    horizontalAdapter = new ForecastHourAdapter(getActivity(), lists);
    LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
    layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
    hlv.setLayoutManager(layoutManager);
    hlv.setAdapter(horizontalAdapter);

运行项目，会报如下的错误：

> 07-14 10:54:15.987 18583-18583/com.gjg.learn.sevenweather E/AndroidRuntime: FATAL EXCEPTION: main  
> java.lang.NullPointerException  
> at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:1694)

特别注意的是，在使用RecyclerView时，必须在setAdapter之前加上如下的代码：

LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
     layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);

参考资料：[http://stackoverflow.com/questions/26737113/java-lang-nullpointerexception-at-android-support-v7-widget-recyclerview-onmeasu][http_stackoverflow.com_questions_26737113_java-lang-nullpointerexception-at-android-support-v7-widget-recyclerview-onmeasu]

[http_stackoverflow.com_questions_26737113_java-lang-nullpointerexception-at-android-support-v7-widget-recyclerview-onmeasu]: http://stackoverflow.com/questions/26737113/java-lang-nullpointerexception-at-android-support-v7-widget-recyclerview-onmeasu