在RecyclerView
问题描述:
我试图获得一个列表,在RecyclerView一个数组,并得到错误setLayoutManager NullPointException:在RecyclerView
java.lang.NullPointerException: Attempt to invoke virtual method
'void android.support.v7.widget.RecyclerView.setLayoutManager
(android.support.v7.widget.RecyclerView$LayoutManager)'on a null object reference
RecyclerView widget的
<android.support.v7.widget.RecyclerView
android:id="@+id/drawerList"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</android.support.v7.widget.RecyclerView>
我试图布局管理申报到最后,但它没有帮助。
活动代码:
public class MainActivity extends ActionBarActivity {
private RecyclerView recyclerView;
private Toolbar toolbar;
private InfAdapter adapter;
@Override
protected void onCreate (Bundle savedInstanceState) {
super.onCreate (savedInstanceState);
setContentView (R.layout.activity_main_appbar);
recyclerView = (RecyclerView) findViewById(R.id.drawerList);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
InfAdapter mAdapter = new InfAdapter(this, getData());
recyclerView.setAdapter(mAdapter);
recyclerView.setItemAnimator(new DefaultItemAnimator());
toolbar = (Toolbar) findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowHomeEnabled(true);
}
适配器代码:
public class InfAdapter extends RecyclerView.Adapter<InfAdapter.MyViewHolder> {
private final Context context;
private List<Information> data = Collections.emptyList();
public InfAdapter(Context context, List<Information> data){
this.data = data;
this.context = context;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_row, parent, false);
return new MyViewHolder(v);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
Information current = data.get(position);
holder.title.setText(current.title);
holder.icon.setImageResource(current.iconid);
}
@Override
public int getItemCount() {
return data.size();
}
class MyViewHolder extends RecyclerView.ViewHolder{
TextView title;
ImageView icon;
public MyViewHolder(View itemView) {
super(itemView);
title = (TextView) itemView.findViewById(R.id.listText);
icon = (ImageView) itemView.findViewById(R.id.listIcon);
}
}
}
了什么可能出了错?
答
由于@StenSoft在评论中所指出的问题是 setContentView (R.layout.activity_main_appbar);
因为错误的活动布局的内容,而不是 setContentView (R.layout.activity_main);
+0
像Charm一样工作! – 2018-01-17 09:25:17
答
在我的情况下,这个错误出现,因为我没有在我的活动之一创建RecyclerView
。
检查您的活动布局或片段布局。
可能重复[什么是空指针异常,以及如何解决它?](http://*.com/questions/218384/what-is-a-null-pointer-exception-and-how -do-i-fix-it) – Simon 2015-02-17 21:02:23
你是否也可以发布你的布局代码....你的布局代码是否有像这样的
Psypher
2015-02-17 21:11:39
@Ranjith是,包括 – Ardi 2015-02-17 21:59:20