Question

我的片段填充ListView 当我在没有List Array的情况下使用它时它工作正常，但是简单的String []具有固定大小，我想填充一个arraylist然后将其转换为String []然后将其提供给listAdapter，因为listAdapter接受String []。但在将Arraylist转换为String []之后，它会给出异常

public class FragmentTab2 extends SherlockFragment {
    private static String url_all_products = "http://192.168.0.104/StepIn/get_all_products.php";

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_PRODUCTS = "products";
    private static final String TAG_PID = "uid";
    private static final String TAG_NAME = "unik";
    private static final String TAG_profile = "uprofile";
    private static final String TAG_location = "ulocation";
    private static final String TAG_isactive = "uisactive";
    private static final String TAG_gcm = "ugcm";
    JSONArray products = null;
    List<String> _nik = new ArrayList<String>(); //get data from JSON
    String[] myid=new String[5];
    String[] nik;
    String[] profile=new String[5];
    String[] location=new String[5];
    String[] isactive=new String[5];
    String[] gcm=new String[5];
    ListView list;
    Activity activity;
    ProgressDialog pDialog;
    View rootView;
    int d=0;
    int a=0;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        rootView = inflater.inflate(R.layout.fragmenttab2, container, false);
        new LoadAllProducts().execute();
        /*  pDialog = new ProgressDialog(getActivity());
        pDialog.setMessage("Getting Users..");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show(); */

        Handler handler = new Handler();
        handler.postDelayed(new Runnable(){
            @Override
            public void run(){
                // do something
            }
        }, 3000);

        //  pDialog.dismiss();


        //  if(nik[0]!=null)
        //  {

        CustomListAdapter adapter=new CustomListAdapter(getActivity(), nik,profile);
        list=(ListView)rootView.findViewById(R.id.list);
        list.setAdapter(adapter);

        list.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // TODO Auto-generated method stub
                int n=+position;
                //Toast.makeText(getActivity().getApplicationContext(), Slecteditem, Toast.LENGTH_SHORT).show();
                Intent i = new Intent (getActivity(),ChatBubbleActivity.class );
                i.putExtra("nik", nik[n]);
                i.putExtra("id", myid[n]);
                i.putExtra("gcm", gcm[n]);

                startActivity(i);
            }
        });
        //}
        //  else
        //{
        //  Toast.makeText(getActivity(), "Plz refresh !\n no user found"+a, Toast.LENGTH_LONG).show();
        //}
    return rootView;
}

/////////////////////////background////////////////////////////////////////
class LoadAllProducts extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    /**
     * getting All products from url
     * */
    protected String doInBackground(String... args) {
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // getting JSON string from URL
        JSONObject json = jParser.makeHttpRequest(url_all_products, "POST", params);

        // Check your log cat for JSON reponse
        Log.d("All Products: ", json.toString() + "");

        try {
            // Checking for SUCCESS TAG
            int success = json.getInt(TAG_SUCCESS);

            if (success == 1) {
                // products found
                // Getting Array of Products
                products = json.getJSONArray(TAG_PRODUCTS);

                // looping through All Products
                for (int i = 0; i < products.length(); i++) {
                    JSONObject c = products.getJSONObject(i);

                    // Storing each json item in variable

                    _nik.add(c.getString(TAG_NAME));
                    //nik[i]=c.getString(TAG_NAME);
                    myid[i] = c.getString(TAG_PID);
                    profile[i] = c.getString(TAG_profile);
                    location[i] = c.getString(TAG_location);
                    isactive[i] = c.getString(TAG_isactive);
                    gcm[i] = c.getString(TAG_gcm);
                    d++;

                    // creating new HashMap
                    //HashMap<String, String> map = new HashMap<String, String>();
                }
                nik = new String[_nik.size()-1];
                 a= _nik.size();
                int b=d;
                b=a;
                nik= _nik.toArray(nik);

            } else {
                // no products found
                // Launch Add New product Activity
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute() {

    }
}

我的自定义适配器

public class CustomListAdapter extends ArrayAdapter<String> {
private final Context context;
private final String[] itemname;
private final String[] imgid;
String my="";
public CustomListAdapter(Context context, String[] itemname, String[] imgid) {
    super(context, R.layout.mylist, itemname);
    // TODO Auto-generated constructor stub

    this.context=context;
    this.itemname=itemname;
    this.imgid=imgid;
}

public View getView(int position,View view,ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View rowView=inflater.inflate(R.layout.mylist, null,true);

    TextView txtTitle = (TextView) rowView.findViewById(R.id.item);
    ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
    TextView extratxt = (TextView) rowView.findViewById(R.id.textView1);

    txtTitle.setText(itemname[position]);
    my=imgid[position];
    Bitmap myy= ImageEncoder.StringToBitMap(my);
    imageView.setImageBitmap(myy);
    extratxt.setText("Description "+itemname[position]);
    return rowView;

};

}

logcat的 Logs

Answer 1

下面：

 CustomListAdapter adapter=new CustomListAdapter(getActivity(), nik,profile);

nik和profile都是null因为AsyncTask是asynchronous调用，它将在后台运行而不会在调用execute方法后执行下一行。

所以，使用onPostExecute方法创建CustomListAdapter对象并将Adapter设置为ListView。

覆盖onPostExecute类中的LoadAllProducts方法：

@Override
    protected void onPostExecute(String result) {
        super.onPostExecute();
        // create and set Adapter for ListView here
        CustomListAdapter adapter=
                        new CustomListAdapter(getActivity(), nik,profile); 
        list.setAdapter(adapter);
    }

在Array，FATAL Exception中将Array List转换为Strig []后，String Array会给出null point异常

1 个答案: