Question

我想构建一个使用毕加索库在gridview中显示图像的应用程序。这是我的代码。图像没有加载。在Picasso日志中，请求后总是加载错误。你能帮助我吗？请谢谢你

更新

CustomGridViewAdapter.Java

import android.app.Activity;
import android.content.ClipData;
import android.content.Context;
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.squareup.picasso.Picasso;

import java.util.ArrayList;

/**
 * Created by Nicky-PC on 4/9/2016.
 */
public class CustomGridViewAdapter extends ArrayAdapter<gridItem> {
    Context context;
    int layoutResourceId;
    ArrayList<gridItem> data = new ArrayList<gridItem>();

    public CustomGridViewAdapter(Context context, int layoutResourceId,
                                 ArrayList<gridItem> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    public void setGridData(ArrayList<gridItem> mGridData)
    {
        this.data=mGridData;
        notifyDataSetChanged();
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        RecordHolder holder;

        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);
            holder = new RecordHolder();
            holder.txtTitle = (TextView) row.findViewById(R.id.tvItem);
            holder.imageItem = (ImageView) row.findViewById(R.id.imageView);
            row.setTag(holder);
        } else {
            holder = (RecordHolder) row.getTag();
        }
        gridItem item = data.get(position);
        holder.txtTitle.setText(item.getBarang());
        Picasso.with(context).
                load(item.getImageUrl()).
                into(holder.imageItem);
        return row;
    }

    static class RecordHolder {
        TextView txtTitle;
        ImageView imageItem;
    }
}

MainActivity.Java

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import android.app.Activity;
import android.media.Image;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

import com.squareup.picasso.Picasso;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

public class MainActivity extends ActionBarActivity {
    JSONParser jParser= new JSONParser();
    ArrayList<HashMap<String, String>> nameList;
    JSONArray names=null;
    GridView data;
    private static final String URL_TEST_BARANG= "http://lomapod.azurewebsites.net/readBarang.php";
    private static final String TAG_PESAN = "message";
    private static final String TAG_HASIL = "result";
    private static final String TAG_BARANG = "nama_barang";
    private static final String TAG_IMAGE= "image_name";
    ImageView imageview;
    CustomGridViewAdapter mGridAdapter;
    ArrayList<gridItem> mGridData;
    public  MainActivity()
    {}

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        data=(GridView) findViewById(R.id.lvSeller);
        nameList= new ArrayList<HashMap<String, String>>();
        imageview =(ImageView) findViewById(R.id.imageView);
        mGridData=new ArrayList<>();
        mGridAdapter=new CustomGridViewAdapter(this,R.layout.grid_item,mGridData);


        new AmbilDataJson("1").execute();
    }


    public class AmbilDataJson extends AsyncTask<String,String,String> {

        String id;
        int sukses=0;

        public AmbilDataJson(String id) {
            this.id=id;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected String doInBackground(String... args) {

            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("id_penjual",id));
            try
            {

                JSONObject json = jParser.makeHttpRequest(URL_TEST_BARANG, "GET", params);
                gridItem item=null;
                if(json != null)
                {
                    sukses = json.getInt(TAG_PESAN);
                    if(sukses == 0)
                    {
                        nameList = new ArrayList<HashMap<String,String>>();
                        Log.d("Semua Nama: ", json.toString());
                        names = json.getJSONArray(TAG_HASIL);

                        for(int i = 0; i < names.length();i++)
                        {
                            JSONObject c = names.getJSONObject(i);
                            String barang = c.getString(TAG_BARANG);
                            String image = "lomapod.esy.es/assets/"+c.getString(TAG_IMAGE);

                            item = new gridItem();
                            item.setBarang(barang);
                            item.setImageUrl(image);

                            HashMap<String,String> map = new HashMap<String,String>();

                            map.put(TAG_BARANG,barang);
                            map.put(TAG_IMAGE,image);
                            nameList.add(map);
                            mGridData.add(item);
                        }
                    }
                }
            }catch(JSONException e)
            {
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            if(sukses == 0)
            {
                CustomGridViewAdapter adapter = new CustomGridViewAdapter(
                        MainActivity.this,R.layout.grid_item,mGridData);
                if(mGridData.size()>0)
                {
                    mGridAdapter.setGridData(mGridData);
                    data.setAdapter(adapter);
                }
                else
                    Toast.makeText(getApplicationContext(),"Error - No Data      Available", Toast.LENGTH_SHORT).show();

            }
            else
            {
                Toast.makeText(MainActivity.this,"Failed",Toast.LENGTH_LONG);
            }
        }
    }
}

Answer 1

CustomGridViewAdapter adapter = new CustomGridViewAdapter(
                    MainActivity.this,R.layout.grid_item,mGridData);
            mGridAdapter.setGridData(mGridData);
            data.setAdapter(adapter);

mGridData为空，您尚未为此列表添加数据。而且你不需要初始化新的适配器。

Answer 2

您没有向mGridData添加值，这就是为什么它没有显示任何内容。在将值传递给适配器之前，请检查mGridData的大小。

    `@Override
    protected void onPostExecute(String s) {
        if(sukses == 0)
        {
            CustomGridViewAdapter adapter = new CustomGridViewAdapter(
                    MainActivity.this,R.layout.grid_item,mGridData);
           if(mGridData.size()>0)
              {
            mGridAdapter.setGridData(mGridData);
            data.setAdapter(adapter);
             }
          else 
            Toast.makeText(getApplicationContext(),"Error - No Data      Available", Toast.LENGTH_SHORT).show();

        }`

Answer 3

GridView没有显示任何内容的原因是因为您传递给ArrayList<gridItem>的{{1}} 为空。

您已在CustomGridViewAdapter初始化了ArrayList<gridItem>，但从未在列表中添加任何项目。

您需要在程序中更改某些内容才能使其正常工作。由于您在MainActivity中添加了服务器响应，因此您需要将ArrayList<HashMap<String, String>> nameList传递给ArrayList，然后使用该ArrayList的项目绑定到您的网格中＆＃39; s Adapter和textView。

在imageView中，将适配器初始化为

onPostExecute()

同时将适配器的构造函数更改为

CustomGridViewAdapter adapter = new CustomGridViewAdapter(MainActivity.this,R.layout.grid_item, nameList);
data.setAdapter(adapter);    
//you don't even need to call mGridAdapter.setGridData(mGridData) method.

使用Picasso在GridView中显示图像

3 个答案: