自定义列表适配器中没有调用getView（）？

Question

这是我的homepage.xml - 其中放置了列表视图：

  <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/background"
        android:orientation="vertical"
        tools:context="com.andapps.azaz.e_recommender.HomePage">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Select Category:"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        />
    <Spinner
        android:id="@+id/spcategorieshomepage"
        android:layout_width="match_parent"
        android:layout_height="35sp"
        android:layout_marginRight="14sp"
        android:spinnerMode="dropdown"
        android:textColor="@color/textColor"
        >


   </Spinner>
    </LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:id="@+id/llhome"
        android:gravity="center"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp">

        <ListView
            android:id="@+id/listView"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent" >


        </ListView>



    </LinearLayout>







</LinearLayout>

还有我的customlist.xml：

 <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Product ID:"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        android:id="@+id/tvproductid"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Product Name:"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        android:id="@+id/tvproductname"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Product Rating:"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        />

    <RatingBar
        android:id="@+id/ratingBar"
        style="?android:attr/ratingBarStyleSmall"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:max="5"
        android:numStars="5" />


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold|italic"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        android:textColor="@color/textColor"
        android:id="@+id/tvproductdesc"
        />
    <ImageView
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:id="@+id/imageView"
        android:layout_marginLeft="15sp"
        android:layout_marginRight="14sp"
        />



</LinearLayout>

我的homepage.java包含使用AsyncTask使用REST API并填充数据数组并将其发送到customAdapter.java

的代码

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home_page);
        lv=(ListView) findViewById(R.id.listView);



        Bundle emailbundle=getIntent().getExtras();
        email=emailbundle.get("email").toString();
        initializer();

        addingItemstoSpinner();

    }


protected void onPostExecute(String result) {

            try {
                jsonArray = new JSONArray(result);
            } catch (JSONException e) {
                e.printStackTrace();
            }
            len= jsonArray.length();
            pdLoading.dismiss();
            if (len != 0) {
                try {




                    String [] productIDListArr= new String[len];
                    String [] productNameListArr= new String[len];
                    String [] productDescListArr= new String[len];
                    String [] productImagesArr= new String[len];
                    String [] productStarsArr= new String[len];
                    for (int i=0;i<len;i++)
                    {
                        objectInArray = jsonArray.getJSONObject(i);

                        productIDListArr[i]=(objectInArray.getString("productId"));
                        productNameListArr[i]=(objectInArray.getString("productName"));
                        productDescListArr[i]=(objectInArray.getString("stars"));
                        productImagesArr[i]=(objectInArray.getString("productId"));
                        productStarsArr[i]=(objectInArray.getString("stars")+" out of 5");




                        if(i==len-1)
                        {
                            createdAt=objectInArray.getString("createdAt");
                        }


                    }
                    lv.setAdapter(new CustomAdapter(HomePage.this, productIDListArr,productNameListArr,productDescListArr,productImagesArr,productStarsArr,email));

                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } else {
                Toast.makeText(getApplicationContext(), "Server is down please try again later", Toast.LENGTH_LONG).show();
            }

我的customAdapter.java

package com.andapps.azaz.e_recommender;

import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.RatingBar;
import android.widget.TextView;
import android.widget.Toast;

import com.squareup.picasso.Picasso;

/**
 * Created by M.Azaz on 30-Mar-17.
 */
public class CustomAdapter extends BaseAdapter {
    String [] productIDListArr,productNameListArr,productDescListArr,productImagesArr,productStarsArr;
    Context context;
    String email;
    private static LayoutInflater inflater=null;

    public CustomAdapter(HomePage homePage, String[] productIDList, String[] productNameList, String[] productDescList, String[] productImages, String[] productStars,String emailMain) {
        // TODO Auto-generated constructor stub
        productIDListArr=productIDList;
        productNameListArr=productNameList;
        productDescListArr=productDescList;
        productImagesArr=productImages;
        productStarsArr=productStars;
        context=homePage;
        email=emailMain;
        inflater = ( LayoutInflater )context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return productIDListArr.length;
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return productIDListArr[position];
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    public class Holder
    {
        TextView tvproductname, tvproductid, tvproductdesc;
        ImageView imageView;
        RatingBar ratingBar;
    }
    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        Holder holder=new Holder();
        View rowView;
        rowView = inflater.inflate(R.layout.activity_custom_list, null);
        holder.tvproductname=(TextView) rowView.findViewById(R.id.tvproductname);
        holder.tvproductid=(TextView) rowView.findViewById(R.id.tvproductid);
        holder.tvproductdesc=(TextView) rowView.findViewById(R.id.tvproductdesc);
        holder.imageView=(ImageView) rowView.findViewById(R.id.imageView);
        holder.ratingBar=(RatingBar) rowView.findViewById(R.id.ratingBar);

        holder.tvproductname.setText(productNameListArr[position]);
        holder.tvproductid.setText(productIDListArr[position]);
        holder.tvproductdesc.setText(productDescListArr[position]);
        holder.ratingBar.setRating(Integer.parseInt(productStarsArr[position]));
        Picasso.with(context).load(context.getString(R.string.imageip) + productImagesArr[position]+".jpg").into(holder.imageView);
        rowView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Toast.makeText(context, "You Clicked "+productIDListArr[position], Toast.LENGTH_LONG).show();
                Intent intent = new Intent("com.andapps.azaz.e_recommender.RATINGS");
                intent.putExtra("tag",productIDListArr[position]);
                intent.putExtra("email", email);
                context.startActivity(intent);
            }
        });
        return rowView;
    }

}

但是当我运行代码时，它实际上会调用customAdapter.java，但是在调用getCount() customAdapter之后它就没有调用getView并且应用程序终止。

还有一件事......如何将更多项目更新到现有列表？

Answer 1

当productIDListArr为null时，您的app可能会在getCount方法中崩溃。因此，在返回count之前，在getCount方法中添加if条件。

例如：

  public int getCount(){
    if(productIDListArr==null){
     return 0;
     }else{
     return  productIDListArr.length;
      }
   }

提示：创建一个用于保存响应数据的类，并将该模型类的列表传递给适配器，并且每次数据更新时都会更改该列表并调用适配器的notify方法。

例如：

     Class Item{
            public String productIDListArr;
            public String productNameListArr;
            public String productDescListArr;
            public String productImagesArr;
            public String productStarsArr;
         }

   ArrayList<Item> items=new ArrayList<Item>();
     for (int i=0;i<len;i++)
       {
        objectInArray = jsonArray.getJSONObject(i);
        Item item=new Item();
        item.productIDListArr=(objectInArray.getString("productId"));
        .......
       }

CustomAdapter extend BaseAdapter{
ArrayList<Item> items;
public CustomAdapter(ArrayList<Item> items){
 this.items=items;
 }     
public int getCount(){
return items==null?0:items.size()
}