未显示集成新闻提要 (ANDROID KITKAT)

Question

所以我正在为爱狗人士创建一个应用程序（大学项目），我正在尝试创建一个集成的新闻提要，显示与狗相关的新闻，并在点击时将用户带到该网站。我制作了一个虚拟应用程序来测试系统并且它运行良好。一旦我将它切换到我当前的 Dog 应用程序，它就完全停止工作了。问题是我用来显示文章列表的 Activity 什么也没有显示。

这里有 2 个活动，一个链接 Activity 和一个 newsItem Activity。链接 Activity 是页面使用的主要 activity 并以特定方式在页面上显示文本。 newsItem Activity 充当 getter 并通过 JSON 文件工作以查找数组中的特定单词并将它们解析回应用程序。我还使用 localHost 来托管 JSON 文件。

如果你们能在这里帮助我，那就太棒了！我完全碰壁了。

Links_Activity Class 连接到 activity_links.xml 文件

newsItem Class 已连接到 Article.xml 文件

Links_Activity Class

   package uk.ac.napier.doggo;

import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;


import com.android.volley.DefaultRetryPolicy;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.squareup.picasso.Picasso;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

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

public class Links_Activity extends AppCompatActivity {

    private List<newsItem> newsFeed = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_links);

        engine();
        addClickListener();

    }

    private void engine() {
        RequestQueue queue = Volley.newRequestQueue(this);

        JsonObjectRequest myReq = new JsonObjectRequest(Request.Method.GET,
                "http://10.0.2.2/news.json",
                null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        try {
                            JSONArray newsItems = response.getJSONArray("newsItems");

                            for (int i = 0; i < newsItems.length(); i++) {
                                JSONObject temp = newsItems.getJSONObject(i);

                                String image = temp.getString("image");
                                String title = temp.getString("title");
                                String time = temp.getString("time");
                                String date = temp.getString("date");
                                String content = temp.getString("content");
                                String link = temp.getString("link");


                                newsFeed.add(new newsItem(title, content, date, time, link, image));

                            }
                        } catch(JSONException e){
                            Log.i("myTag", e.toString());
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.i("myTag", error.toString());
                    }
                });



        myReq.setRetryPolicy(new DefaultRetryPolicy(
                30*1000,
                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
        queue.add(myReq);



        ArrayAdapter<newsItem> adapter = new customAdapter();

        ListView  newsItems = (ListView) (findViewById(R.id.newsItems));
        newsItems.setAdapter(adapter);

    }

    private void addClickListener() {
        ListView newsItems = (ListView) (findViewById(R.id.newsItems));
        newsItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                newsItem currentItem = newsFeed.get(position);
                Intent i = new Intent (Intent.ACTION_VIEW);
                i.setData(Uri.parse(currentItem.getUrl()));
                startActivity(i);
            }
        });
    }



        private class customAdapter extends ArrayAdapter<newsItem> {
                public customAdapter() {
            super(Links_Activity.this, R.layout.article, newsFeed);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            if(convertView == null) {
                convertView = getLayoutInflater().inflate(R.layout.article, parent, false);
            }

            newsItem currentItem = newsFeed.get(position);

            ImageView newsImage = (ImageView) convertView.findViewById(R.id.leftIco);
            TextView heading = (TextView) convertView.findViewById(R.id.heading);
            TextView desc = (TextView) convertView.findViewById(R.id.desc);

            heading.setText(currentItem.getNewsHeading());
            desc.setText(currentItem.getNewsDesc());

            Picasso.with(Links_Activity.this).load(currentItem.getImageURL()).into(newsImage);


            return convertView;
        }

    }

    public void Back(View view) {
        Intent startBackActivity = new Intent(this, Menu_Activity.class);
        startActivity(startBackActivity);
    }
}

activity_links.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="match_parent"
    android:layout_height="wrap_content"
    android:text="News Feed"
    android:textSize="25sp"
    android:textAlignment="center"
    android:id="@+id/logo"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"/>

<TextView
    android:text="Articles Courtesy of Dogster.com"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView"
    android:layout_alignParentBottom="true"
    android:layout_alignParentStart="true" />

<ListView
    android:layout_width="wrap_content"
    android:layout_height="400dp"
    android:id="@+id/newsItems"
    android:layout_centerVertical="true"
    android:layout_alignParentStart="true" />

</RelativeLayout>

newsItem Class

package uk.ac.napier.doggo;

import java.util.PriorityQueue;

/**
 * Created by MarkB on 10/03/2017.
 */

public class newsItem {

    private String newsHeading;
    private String newsDesc;
    private String newsDescSmall;
    private String time;
    private String date;
    private String url;
    private String imageURL;

    public newsItem(String newsHeading, String newsDesc, String date,  String time, String url, String imageURL) {
        this.newsHeading = newsHeading;
        this.newsDesc = newsDesc;
        this.time = time;
        this.date = date;
        this.url = url;
        this.imageURL = imageURL;

        this.newsDescSmall = this.newsDesc.substring(0, 50) + "...";
    }

    public String getNewsHeading() {
        return newsHeading;
    }

    public String getNewsDesc() {
        return newsDesc;
    }

    public String getTime() {
        return time;
    }

    public String getDate() {
        return date;
    }

    public String getUrl() {
        return url;
    }

    public String getImageURL() {
        return imageURL;
    }
}

article.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp">

<ImageView
    android:layout_width="80dp"
    android:layout_height="100dp"
    android:id="@+id/leftIco"
    android:src="@mipmap/ic_launcher"
    android:maxHeight="100dp"
    android:maxWidth="100dp"
    android:adjustViewBounds="true"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="16sp"
    android:text="Heading Text"
    android:id="@+id/heading"
    android:scrollHorizontally="false"
    android:maxLines="100"
    android:ellipsize="none"
    android:layout_alignParentTop="true"
    android:layout_toRightOf="@+id/leftIco"
    android:layout_toEndOf="@+id/leftIco"
    android:layout_marginLeft="24dp"
    android:layout_marginStart="24dp"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Description"
    android:id="@+id/desc"
    android:lineSpacingExtra="-3dp"
    android:layout_marginBottom="26dp"
    android:layout_alignBottom="@+id/leftIco"
    android:layout_alignLeft="@+id/heading"
    android:layout_alignStart="@+id/heading"/>




</RelativeLayout>

AndroidManifest.xml供参考

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="uk.ac.napier.doggo">

    <uses-permission android:name="android.permission.INTERNET">
</uses-permission>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Home_Screen_Activity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".Details_Activity" />
        <activity android:name=".Menu_Activity" />
        <activity android:name=".Reminders_Activity" />
        <activity android:name=".Health_Tracker_Activity" />
        <activity android:name=".Routes_Activity" />
        <activity android:name=".Route_Complete_Activity" />
        <activity android:name=".History_Activity" />
        <activity android:name=".Links_Activity" >

        </activity>

        <activity android:name=".TimePopUp_Activity"
        android:theme="@style/AppTheme.CustomTheme" >
        </activity>

    </application>

</manifest>

最后 news.JSON 文件

{"newsItems":[
{
"image": "http://www.dogster.com/wp-content/uploads/2017/03/16806949_152063731974308_6992949846293798966_n-Cropped.jpg",
"title": "Artist Arien Smith Imagines Disney Princesses With Service Dogs",
"time": "10:00am ",
"date": "22 Jun ",
"content": "So far, the artist has drawn Cinderella and Snow White with     service dogs, with the hope of raising awareness and money for his own helper.",
"link": "http://www.dogster.com/lifestyle/artist-arien-smith-imagines-disney-princesses-with-service-dogs"
},
{
"image": "http://www.dogster.com/wp-content/uploads/2016/06/Stalking-predatory-hero.png",
"title": "Is Your Dog a Bully?",
"time":"12:00am ",
"date":"Jun 12",
"content": "Dogs who bully not only start fights, but they can turn timid dogs into bullies themselves. Let's look at the signs of bullying and how to help your dog stop this behavior.",
"link": "http://www.dogster.com/lifestyle/is-your-dog-a-bully"
}
]
}

Answer 1

试试这个：

将数组项传递给适配器：

customAdapter adapter = new customAdapter(this, newsFeed);
ListView  newsItems = (ListView) (findViewById(R.id.newsItems));
newsItems.setAdapter(adapter);

现在在适配器 class 中使用：

private List<newsItem> newsFeed_list ;

   public customAdapter(Context context, ArrayList<newsItem> items) {
        super(context, items);
        this.newsFeed_list = items;
    }

并使用以下方法获取对象：

newsItem currentItem = newsFeed_list.get(position);

Answer 2

你从未打电话给adapter.notifyDataSetChanged()

        newsFeed.add(new newsItem(title, content, date, time, link, image));
    }  // end loop
    // notify the adapter to display the new data 
    adapter.notifyDataSetChanged()
} catch(JSONException e){
    Log.i("myTag", e.toString());
}

但是，你有一个 ArrayAdapter，所以只需添加它，而不是 Arraylist 那么你不需要通知

        // See here
        adapter.add(new newsItem(title, content, date, time, link, image));
    }  // end loop
} catch(JSONException e){
    Log.i("myTag", e.toString());
}

对您的代码进行一些重新安排应该可以。

public class LinksActivity extends AppCompatActivity 
  implements AdapterView.OnItemClickListener, Response.ErrorListener {

    private List<NewsItem> newsFeed = new ArrayList<>();
    private ArrayAdapter<NewsItem>  adapter;

    // Moved the Volley response to top-level
    private Response.Listener<JSONObject>  newsListener = new Response.Listener<JSONObject>()  {        

        @Override
        public void onResponse(JSONObject response) {
            try {
                JSONArray newsItems = response.getJSONArray("newsItems");

                for (int i = 0; i < newsItems.length(); i++) {
                    JSONObject temp = newsItems.getJSONObject(i);

                    String image = temp.getString("image");
                    String title = temp.getString("title");
                    String time = temp.getString("time");
                    String date = temp.getString("date");
                    String content = temp.getString("content");
                    String link = temp.getString("link");


                    newsFeed.add(new newsItem(title, content, date, time, link, image));
                }

                // Important!
                adapter.notifyDataSetChanged();

            } catch(JSONException e){
                Log.i("myTag", e.toString());
            }
        }
    };

    // This is Volley's error listener over the entire Activity
    @Override
    public void onErrorResponse(VolleyError error) {
        Log.i("myTag", error.toString());
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_links);

        // Set and define the List and Adapter here
        ListView  newsItems = (ListView) findViewById(R.id.newsItems);
        newsItems.setOnItemClickListener(this);

        adapter = new CustomAdapter();
        newsItems.setAdapter(adapter);

        engine();
    }

    private void engine() {
        RequestQueue queue = Volley.newRequestQueue(this);

        // Now this method is much 'cleaner'
        JsonObjectRequest myReq = new JsonObjectRequest(Request.Method.GET,
                "http://10.0.2.2/news.json",
                null, 
                newsListener, this);

        myReq.setRetryPolicy(new DefaultRetryPolicy(
                30*1000,
                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
        queue.add(myReq);
    }

    // The Activity itself handles the clicking
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        NewsItem currentItem = newsFeed.get(position);
        Intent i = new Intent (Intent.ACTION_VIEW);
        i.setData(Uri.parse(currentItem.getUrl()));
        startActivity(i);
    }
}

未显示集成新闻提要 (ANDROID KITKAT)

Integrated News feed not displaying (ANDROID KITKAT)

java

android

json

xml

feed