如何在片段中动态添加视图
How to add a view dynamically inside a fragment
我正在制作 RecyclerView inside a fragment
。我通过 Java 代码创建了 RecyclerView Adapter 和 LinearLayoutManager 的对象。
public class RFPMenuFragment extends Fragment{
List<MyRFP> myRFPList;
RecyclerView recyclerViewRFP;
RVAdapterRFP rvAdapterRFP;
LinearLayoutManager llm;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//return super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.single_feed, container, false);
recyclerViewRFP = (RecyclerView) view.findViewById(R.id.recycler_view_rfp);
initializeData();
rvAdapterRFP = new RVAdapterRFP(myRFPList);
recyclerViewRFP.setAdapter(rvAdapterRFP);
llm = new LinearLayoutManager(getActivity());
recyclerViewRFP.setLayoutManager(llm);
return view;
}
但是它在具有 setAdapter 方法的行上给了我一个 NullPointerException
。即使我删除了 2 条 Adapter 行,我也会在 setLayoutManager 方法上收到此错误。我该如何解决这个问题?
这是我的 LogCat:
Process: com.example.h8pathak.jobs, PID: 26848
java.lang.NullPointerException
at com.example.h8pathak.jobs.rfp.RFPMenuFragment.onCreateView(RFPMenuFragment.java:41)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2074)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1286)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1671)
at android.support.v4.app.FragmentManagerImpl.run(FragmentManager.java:532)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:149)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
at dalvik.system.NativeStart.main(Native Method)
在 onCreateView
中,该片段尚未附加到 activity,因此 getActivity()
returns 为空。您需要在 onActivityCreated()
中实例化您的布局管理器、适配器和回收视图
编辑:代码
public class RFPMenuFragment extends Fragment{
List<MyRFP> myRFPList;
RecyclerView recyclerViewRFP;
RVAdapterRFP rvAdapterRFP;
LinearLayoutManager llm;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//return super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.single_feed, container, false);
recyclerViewRFP = (RecyclerView) view.findViewById(R.id.recycler_view_rfp);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
initializeData();
rvAdapterRFP = new RVAdapterRFP(myRFPList);
recyclerViewRFP.setAdapter(rvAdapterRFP);
llm = new LinearLayoutManager(getActivity());
recyclerViewRFP.setLayoutManager(llm);
}
按照 Drup Desai 的建议,在设置适配器之前尝试设置布局管理器。
检查方法 initializeData()
是否真的在初始化和填充您的数据列表。当适配器连接到 RecyclerView
.
时,null
列表可能会导致 NPE
您似乎还没有在 single_feed 布局中添加 RecyclerView。
如果是这样,请在您希望 RecyclerView 填充数据的布局中添加以下部分。
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
在您的情况下,请在您的 RFPMenuFragment.java
中提及具有 RecyclerView 而不是 single_feed 布局的布局(如果有,如其名称所示)。
我正在制作 RecyclerView inside a fragment
。我通过 Java 代码创建了 RecyclerView Adapter 和 LinearLayoutManager 的对象。
public class RFPMenuFragment extends Fragment{
List<MyRFP> myRFPList;
RecyclerView recyclerViewRFP;
RVAdapterRFP rvAdapterRFP;
LinearLayoutManager llm;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//return super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.single_feed, container, false);
recyclerViewRFP = (RecyclerView) view.findViewById(R.id.recycler_view_rfp);
initializeData();
rvAdapterRFP = new RVAdapterRFP(myRFPList);
recyclerViewRFP.setAdapter(rvAdapterRFP);
llm = new LinearLayoutManager(getActivity());
recyclerViewRFP.setLayoutManager(llm);
return view;
}
但是它在具有 setAdapter 方法的行上给了我一个 NullPointerException
。即使我删除了 2 条 Adapter 行,我也会在 setLayoutManager 方法上收到此错误。我该如何解决这个问题?
这是我的 LogCat:
Process: com.example.h8pathak.jobs, PID: 26848
java.lang.NullPointerException
at com.example.h8pathak.jobs.rfp.RFPMenuFragment.onCreateView(RFPMenuFragment.java:41)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2074)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1286)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1671)
at android.support.v4.app.FragmentManagerImpl.run(FragmentManager.java:532)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:149)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
at dalvik.system.NativeStart.main(Native Method)
在 onCreateView
中,该片段尚未附加到 activity,因此 getActivity()
returns 为空。您需要在 onActivityCreated()
编辑:代码
public class RFPMenuFragment extends Fragment{
List<MyRFP> myRFPList;
RecyclerView recyclerViewRFP;
RVAdapterRFP rvAdapterRFP;
LinearLayoutManager llm;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//return super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.single_feed, container, false);
recyclerViewRFP = (RecyclerView) view.findViewById(R.id.recycler_view_rfp);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
initializeData();
rvAdapterRFP = new RVAdapterRFP(myRFPList);
recyclerViewRFP.setAdapter(rvAdapterRFP);
llm = new LinearLayoutManager(getActivity());
recyclerViewRFP.setLayoutManager(llm);
}
按照 Drup Desai 的建议,在设置适配器之前尝试设置布局管理器。
检查方法
initializeData()
是否真的在初始化和填充您的数据列表。当适配器连接到RecyclerView
. 时,
null
列表可能会导致 NPE
您似乎还没有在 single_feed 布局中添加 RecyclerView。
如果是这样,请在您希望 RecyclerView 填充数据的布局中添加以下部分。
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
在您的情况下,请在您的 RFPMenuFragment.java
中提及具有 RecyclerView 而不是 single_feed 布局的布局(如果有,如其名称所示)。