java - 数组列表和 ListView

Question

我正在尝试从 json 中获取数据。实际上它正在工作，但我的 listview 有问题。我收到错误。

这是代码； 主 Activity .java

  

public class MainActivity extends AppCompatActivity {
    TextView txt;
    Places places=new Places();
    ListView listView;
    List<Places> PlacesList=new ArrayList<>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        txt= (TextView) findViewById(R.id.text);
        listView= (ListView) findViewById(R.id.listView);
        listView.setBackgroundColor(Color.BLACK);
        new getData().execute("https://api.foursquare.com/v2/venues/search?ll=41,29&oauth_token=01ZV1VDLE41USSRAYJUXOWNJ2MXYCAVN1I2PQFLFBCD40XYI&v=20160304");

    }
    public class getData extends AsyncTask<String,String,List <Places>> {
        HttpURLConnection conn=null;
        URL url=null;
        BufferedReader bReader=null;
        String name=null;
        @Override
        protected List<Places> doInBackground(String... params) {
            try {
                //BURADA URL'E BAGLANDIK
                url=new URL(params[0]);
                conn= (HttpURLConnection) url.openConnection();
                conn.setRequestMethod("GET");
                conn.setDoInput(true);
                conn.connect();
                //VERİ OKUMAK İÇİN STREAM KULLANACAZ
                InputStream istream=conn.getInputStream();
                bReader= new BufferedReader(new InputStreamReader(istream));
                //VERİ DEPOLAMAK İÇİN StringBuffer
                StringBuffer sBuffer=new StringBuffer();
                String line="";
                while((line=bReader.readLine())!=null){
                    sBuffer.append(line);
                }
                String JSONFinal=sBuffer.toString();
                JSONObject jsonObject=new JSONObject(JSONFinal);
                JSONArray jsonArray=jsonObject.getJSONObject("response").getJSONArray("venues");
                StringBuffer finalBuffer=new StringBuffer();
                for(int i=0;i<jsonArray.length();i++) {
                    JSONObject finalJsonObject = jsonArray.getJSONObject(i);
                    name = finalJsonObject.getString("name");
                    places.setName(name);
                    PlacesList.add(places);
                }

                return  PlacesList;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }
            finally {
                conn.disconnect();
            }
            return null;
        }

        @Override
        protected void onPostExecute( List<Places> PlacesList) {
            super.onPostExecute(PlacesList);
            ArrayAdapter adapter=  new ArrayAdapter<Places>(getApplicationContext(),android.R.layout.simple_list_item_1,PlacesList);
            listView.setAdapter(adapter);

        }
    }

Places.java

public class Places {
    int id,lat,lng;
    String name;



    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

那么问题是什么？

Answer 1

之所以这样显示，是因为您已将 Places 对象传递给您的 ListView ，并且您没有提供要从 Places 对象显示在 ListView 中的字段，你可能应该在你的 Places 对象中提供 toString() 方法来查看你的名称列表，或者你应该创建你自己的适配器实现

查看带有名称的 ListView

将此添加到您的 Places 类中

public void toString(){
return name;
}