Question

我有一个自定义适配器，我需要在onPostExecute方法中使用它来填充带有图像和文本的ListView。

这是自定义适配器

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;


public class MyAdapter extends BaseAdapter {


    private Activity mActivity;
    private ArrayList listaElementi;
    private static LayoutInflater infilater = null;

    public MyAdapter( Activity a, ArrayList list) {
        mActivity = a;
        listaElementi = list;
        infilater = (LayoutInflater) mActivity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return listaElementi.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View vi = convertView;
        if( convertView == null )
            vi = infilater.inflate(R.layout.riga, null);

        TextView nome = (TextView) vi.findViewById(R.id.nome);
        ImageView immagine = (ImageView) vi.findViewById(R.id.immagine);

        Riga rigaCorrente = (Riga) listaElementi.get(position);
        nome.setText(rigaCorrente.getNome());
        immagine.setImageDrawable(mActivity.getResources().getDrawable(rigaCorrente.getImmagine()));
        return vi;
    }

}

这是我的onPostExecute方法：

private class LongOperation extends AsyncTask<String, String, JSONObject> {

     //Other methods here

     protected void onPostExecute(JSONObject result) {

            JSONObject jobj = null;
            JSONArray elenco_cartelle = null;

            try {

                jobj = new JSONObject(String.valueOf(result));

            } catch (JSONException e) {
                e.printStackTrace();
            }

            //Provo a recuperare i campi json
            try {

                elenco_cartelle = jobj.getJSONArray("elenco");

            } catch (JSONException e) {
                e.printStackTrace();
            }

            ArrayList<Riga> arrayCartelle = new ArrayList<Riga>();

            //DEvo scorrere le'elenco delle cartelle
            for (int i = 0; i < elenco_cartelle.length(); i++) {

                try {

                    String nome = elenco_cartelle.getString(i);

                    arrayCartelle.add( new Riga( nome , R.drawable.ic_launcher ) );


                } catch (JSONException e) {
                    e.printStackTrace();
                }

            }

            MyAdapter myAdapter = new MyAdapter(CartelleActivity.class,arrayCartelle);


            mainListView.setAdapter(myAdapter);

            // Close progress dialog
            Dialog.dismiss();

        }
}

这是我的里加课程

public class Riga {
    String nome;
    Integer idImmagine;

    public Riga( String nome, Integer idImmagine ) {
        super();
        this.nome = nome;
        this.idImmagine = idImmagine;

    }

    public String getNome() {
        return this.nome;
    }

    public Integer getImmagine() {
        return this.idImmagine;
    }

    public void setNome( String nome ) {
        this.nome = nome;
    }

    public void setIdImmagine( Integer idImmagine ) {
        this.idImmagine = idImmagine;
    }
}

问题在于这一行：

MyAdapter myAdapter = new MyAdapter(CartelleActivity.class,arrayCartelle);

IDE（AndroidStudio）说我不能使用CartelleActivity 我该如何使用我的适配器？

Answer 1

解决。使用：

CartelleActivity.this

代替

CartelleActivity.class

Answer 2

你的代码中有些东西可疑。尝试通过将适配器更改为ArrayList：

来定义适配器中的ArrayList<Riga>

    private Activity mActivity;
    private ArrayList<Riga> listaElementi;
    private static LayoutInflater infilater = null;

    public MyAdapter( Activity a, ArrayList<Riga> list) {
        mActivity = a;
        listaElementi = list;
        infilater = (LayoutInflater) mActivity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

Answer 3

public class LongOperation extends AsyncTask<String, String, JSONObject> {

    private Activity a;

    public CustomAsync(Activity a) {
        this.a = a;
    }

    @Override
    protected JSONObject doInBackground(String... params) {
        // TODO Auto-generated method stub
        return null;
    }


    @Override
    protected void onPostExecute(JSONObject result) {
        super.onPostExecute(result);
        MyAdapter myAdapter = new MyAdapter(a, new ArrayList());
    }


}

Android - 自定义适配器和AsyncTask

3 个答案: