当我在GridView中使用setOnItemClickListener时返回null

时间：2018-05-29 11:02:33

标签： java android firebase gridview google-cloud-firestore

当我使用setOnItemClickListener获取GridView返回null中点击的项目的ID时出现问题。我尝试这样做，因为我想当用户点击一个项目我从db检索数据然后在另一个片段中表示它，所以有一个解决方案来获取id或有另一种方法来处理它。非常感谢。

我使用适配器：

fragment.java 

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;

import com.example.mohamed.osarelkheir.Adapters.Section_Adapter;
import com.example.mohamed.osarelkheir.First_Launch;
import com.example.mohamed.osarelkheir.Models.Section_Model;
import com.example.mohamed.osarelkheir.R;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.firestore.DocumentChange;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.EventListener;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreException;
import com.google.firebase.firestore.Query;
import com.google.firebase.firestore.QuerySnapshot;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class Sections_Fragment extends Fragment {

    private GridView Dep_grid_View; //object from GridView (list) -Session Fragment
    private List<Section_Model> Dep_list; //Data Model Object
    private Section_Adapter section_adapter; //Adapter Object

    private FirebaseFirestore firebaseFirestore;
    private FirebaseAuth firebaseAuth;

    private String Dep_id;
    private String item;

    private DocumentSnapshot lastVisible; //to print the last ....

    //Empty Contractor
    public Sections_Fragment() {

    }

    private FragmentManager fragmentManager;


    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.section_fragment, container, false);

        Dep_grid_View = view.findViewById(R.id.gridSection);
        Dep_list = new ArrayList<>();

        firebaseAuth = FirebaseAuth.getInstance();
        firebaseFirestore = FirebaseFirestore.getInstance();


//        myList = Arrays.asList(section_models); //he create its own array list to view it as a templet data cooooool
        section_adapter = new Section_Adapter(getContext(), Dep_list);
        Dep_grid_View.setAdapter(section_adapter);


        //First Query
        Query firstQuery = firebaseFirestore.collection("Department");
        firstQuery.addSnapshotListener(getActivity(), new EventListener<QuerySnapshot>() {
            @Override
            public void onEvent(@javax.annotation.Nullable QuerySnapshot snapshots, @javax.annotation.Nullable FirebaseFirestoreException e) {
//                Toast.makeText(getActivity(), "No", Toast.LENGTH_SHORT).show();

                for (DocumentChange doc : snapshots.getDocumentChanges()) {
//                    Toast.makeText(getActivity(), "NoO", Toast.LENGTH_SHORT).show();

                    if (doc.getType() == DocumentChange.Type.ADDED) {

//                        Toast.makeText(getActivity(), "No00", Toast.LENGTH_SHORT).show();

                        Dep_id = doc.getDocument().getId();

                        Toast.makeText(getActivity(), "Id" + Dep_id, Toast.LENGTH_SHORT).show();


                        // <<<<<<<<<<<<<GET DATA from DB >>>>>>>>>>>>>>>>>>
                        Section_Model section_model = doc.getDocument().toObject(Section_Model.class).withId(Dep_id);

                        //<<<<<<<<<<<<<<<then Put it in object of  BlogList >>>>>>>>>>>>>>
                        Dep_list.add(section_model);

                        section_adapter.notifyDataSetChanged();

                    }
                }
            }
        });


        Dep_grid_View.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

                 //it's return null 
                item = Dep_grid_View.getItemAtPosition(i).toString();

                printadminview();
            }
        });

        return view;
    }

    void printadminview() {
        Intent intent = new Intent(getContext(), First_Launch.class);
        intent.putExtra("value", 3);
        intent.putExtra("Dep_ID", item );
//        Toast.makeText(getActivity(), "pos " + pos, Toast.LENGTH_SHORT).show();
        getContext().startActivity(intent);
    }

}

.xml文件

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <SearchView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:background="@drawable/item_background_manage"
            android:layout_marginTop="5dp"
            android:layout_marginEnd="5dp"
            android:layout_marginStart="5dp"
            android:layout_weight="1"
            android:queryHint="search"/>

    </LinearLayout>

    <GridView
        android:id="@+id/gridSection"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="auto_fit"
        android:verticalSpacing="5dp"
        android:horizontalSpacing="3dp"
        android:layout_margin="8dp" />
</LinearLayout>

适配器类

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.RequestOptions;
import com.example.mohamed.osarelkheir.First_Launch;
import com.example.mohamed.osarelkheir.Models.Section_Model;
import com.example.mohamed.osarelkheir.R;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.firestore.FirebaseFirestore;

import java.util.List;

public class Section_Adapter extends ArrayAdapter<Section_Model> { //1

    private Context mContext;
    private List<Section_Model> data;


    public Section_Adapter(Context mContext,List<Section_Model> data) {//2
        super(mContext,R.layout.item_section,data);
        this.mContext = mContext;
        this.data = data;
    }




      @Override
public View getView(int position, View convertView, @NonNull ViewGroup parent) {
    View row = convertView;
    ViewHolder holder;
    if (row == null) {
        LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
        row = inflater.inflate(R.layout.item_section, parent, false);
        holder = new ViewHolder();
        holder.txtSectionName = row.findViewById(R.id.sectionName);
        holder.imageView = row.findViewById(R.id.imageSection);
        holder.imageIc = row.findViewById(R.id.ic_sec);
        row.setTag(holder);
        row.setTag(new Integer(position));

    } else {
        holder = (ViewHolder) row.getTag();
    }
    setView(holder, position);

    Section_Model model = getItem(position);
    String id = model.getId();
    Intent intent=new Intent(mContext, First_Launch.class);
            intent.putExtra("value",1);
            intent.putExtra("DepartmentId", id);
            mContext.startActivity(intent);

    return row;
}

    private void setView(ViewHolder holder, int position) {
        Section_Model section_model = data.get(position);

        holder.txtSectionName.setText(section_model.getSection_name());

        String downlaodUriImage = section_model.getSection_image();
        String DownloadUriLogo = section_model.getSection_icon();
        RequestOptions requestOptions = new RequestOptions();
        requestOptions.placeholder(R.drawable.logo);
        Glide.with(mContext).applyDefaultRequestOptions(requestOptions).load(downlaodUriImage).into(holder.imageView);
        Glide.with(mContext).load(DownloadUriLogo).apply(requestOptions.override(40,40)).into(holder.imageIc);



    }

        static class ViewHolder {
            TextView txtSectionName;
            ImageView imageView;
            ImageView imageIc;
        }


    }

1 个答案:

答案 0 :(得分：1)

要仅获取ID，您只需使用以下代码行。

firstQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (QueryDocumentSnapshot document : task.getResult()) {
                String documentId = document.getId();
                Log.d(TAG, documentId);
            }
        }
    }
});

除非您需要实时获取数据，否则无需使用addSnapshotListener。输出将是：

CIcg...
E30F...
rXY9...

如果您需要获取所点击的项目的相应ID，只需使用getItem(position);

根据您的评论，最简单的方法是在名为Section_Model的{​​{1}}类中添加一个新属性，以便存储每个特定文档的ID。因此，每次添加新文档时，该文档都将包含id。使用id将返回getItem(position)类的对象。请参阅以下代码：

Section_Model

因此，Section_Model model = getItem(position); String id = model.getId(); 将返回将该文档添加到数据库时设置的对象的ID。

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