RecyclerView与片段 [英] RecyclerView with Fragments
本文介绍了RecyclerView与片段的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我想使用新的 RecyclerView
控件放置在片段
,但我收到此错误:
I am trying to use the new RecyclerView
widget inside a Fragment
but I am getting this error:
无法启动活动ComponentInfo {com.example.myapplication / com.example.myapplication.MyActivity}:显示java.lang.NullPointerException:尝试调用接口方法布尔java.util.List.add在一个空对象引用(java.lang.Object中)
我是什么做错了吗?
这是我的片段
:
import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.List;
public class RecyclerviewFragment extends Fragment {
private RecyclerView mRecyclerView;
private RecyclerviewAdapter mRecyclerviewAdapter;
private LinearLayoutManager mLinearLayoutManager;
private List<ViewModel> viewModel;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_recyclerview, container, false);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mRecyclerviewAdapter = new RecyclerviewAdapter(viewModel);
mLinearLayoutManager = new LinearLayoutManager(getActivity());
mRecyclerView.setAdapter(mRecyclerviewAdapter);
mRecyclerView.setLayoutManager(mLinearLayoutManager);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
}
}
和我的活动:
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import java.util.List;
public class MyActivity extends Activity {
private List<ViewModel> viewModel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
RecyclerviewFragment recyclerviewFragment = new RecyclerviewFragment();
getFragmentManager().beginTransaction().add(android.R.id.content, recyclerviewFragment).commit();
viewModel.add(new ViewModel("View"));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.my, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
谢谢!
推荐答案
您没有初始化私人列表&LT;视图模型&GT;视图模型
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