在我的应用程序中打开片段时遇到此异常。 java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'void android.support.v7.widget.RecyclerView.setHasFixedSize（boolean）'
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setHasFixedSize(boolean)' on a null object reference
at com.hotwings.truekitchen.TabCookMenu.onCreateView(TabCookMenu.java:61)
at android.app.Fragment.performCreateView(Fragment.java:2508)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1279)
at android.app.FragmentManagerImpl.addAddedFragments(FragmentManager.java:2407)
at android.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2186)
at android.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2142)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2043)
import android.app.Fragment;
import android.os.Bundle;
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 android.widget.LinearLayout;
import java.util.ArrayList;
import java.util.List;
public class TabCookMenu extends Fragment {
public static TabCookMenu newInstance() {
return new TabCookMenu();
}
LinearLayout linearLayout;
View rootView;
private String url = "http://192.168.43.196/Volley/data.json";
List<CookMenuList> productList;
//the recyclerview
RecyclerView recyclerView;
//
// @Override
// public View onCreateView(LayoutInflater inflater, ViewGroup container,
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Inflate the layout for this fragment
rootView = inflater.inflate(R.layout.singlecookmenulist, container, false);
//getting the recyclerview from xml
recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
productList = new ArrayList<>();
//adding some items to our list
productList.add(
new CookMenuList(
1,
"Apple MacBook Air Core i5 5th Gen - (8 GB/128 GB SSD/Mac OS Sierra)",
"13.3 inch, Silver, 1.35 kg",
4.3,
60000,
R.drawable.ic_drawer));
productList.add(
new CookMenuList(
1,
"Dell Inspiron 7000 Core i5 7th Gen - (8 GB/1 TB HDD/Windows 10 Home)",
"14 inch, Gray, 1.659 kg",
4.3,
60000,
R.drawable.ic_home));
productList.add(
new CookMenuList(
1,
"Microsoft Surface Pro 4 Core m3 6th Gen - (4 GB/128 GB SSD/Windows 10)",
"13.3 inch, Silver, 1.35 kg",
4.3,
60000,
R.drawable.ic_trash));
//creating recyclerview adapter
//
CookMenuAdaptor adapter = new CookMenuAdaptor(getActivity(), productList);
//setting adapter to recyclerview
recyclerView.setAdapter(adapter);
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
llm.setOrientation(LinearLayoutManager.VERTICAL);
recyclerView.setLayoutManager(llm);
return rootView;
}
}
这是我要在其中添加的清单XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="8dp">
<ImageView
android:id="@+id/imageView"
android:layout_width="120dp"
android:layout_height="90dp"
android:padding="4dp" />
<TextView
android:id="@+id/textViewTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_toRightOf="@id/imageView"
android:text="Apple MacBook Air Core i5 5th Gen - (8 GB/128 GB SSD/Mac OS Sierra)"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Small"
android:textColor="#000000" />
<TextView
android:id="@+id/textViewShortDesc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewTitle"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/imageView"
android:text="13.3 Inch, 256 GB"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Small" />
<TextView
android:id="@+id/textViewRating"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewShortDesc"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/imageView"
android:background="@color/colorPrimary"
android:paddingLeft="15dp"
android:paddingRight="15dp"
android:text="4.7"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Small.Inverse"
android:textStyle="bold" />
<TextView
android:id="@+id/textViewPrice"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewRating"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/imageView"
android:text="INR 56990"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Large"
android:textStyle="bold" />
</RelativeLayout>
enter code here
</android.support.v7.widget.CardView>
</LinearLayout>
<?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="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;
public class CookMenuAdaptor extends RecyclerView.Adapter<CookMenuAdaptor.ProductViewHolder> {
//this context we will use to inflate the layout
private Context mCtx;
//we are storing all the products in a list
private List<CookMenuList> productList;
//getting the context and product list with constructor
public CookMenuAdaptor(Context mCtx, List<CookMenuList> productList) {
this.mCtx = mCtx;
this.productList = productList;
}
@Override
public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//inflating and returning our view holder
// LayoutInflater inflater = LayoutInflater.from(mCtx);
// View view = inflater.inflate(R.layout.singlecookmenulist, null);
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = inflater.inflate(R.layout.singlecookmenulist, parent, false);
return new ProductViewHolder(view);
}
@Override
public void onBindViewHolder(ProductViewHolder holder, int position) {
//getting the product of the specified position
CookMenuList product = productList.get(position);
//binding the data with the viewholder views
holder.textViewTitle.setText(product.getTitle());
holder.textViewShortDesc.setText(product.getShortdesc());
holder.textViewRating.setText(String.valueOf(product.getRating()));
holder.textViewPrice.setText(String.valueOf(product.getPrice()));
holder.imageView.setImageDrawable(mCtx.getResources().getDrawable(product.getImage()));
}
@Override
public int getItemCount() {
return productList.size();
}
class ProductViewHolder extends RecyclerView.ViewHolder {
TextView textViewTitle, textViewShortDesc, textViewRating, textViewPrice;
ImageView imageView;
public ProductViewHolder(View itemView) {
super(itemView);
textViewTitle = itemView.findViewById(R.id.textViewTitle);
textViewShortDesc = itemView.findViewById(R.id.textViewShortDesc);
textViewRating = itemView.findViewById(R.id.textViewRating);
textViewPrice = itemView.findViewById(R.id.textViewPrice);
imageView = itemView.findViewById(R.id.imageView);
}
}
}
我尝试了各种选项并从包括stackoverflow在内的各种来源获得了帮助，但是我仍然遇到此问题。