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我使用ListActivity和我解析JSON并把它放在我的自定义适配器ListActivity即显示它，空指针异常
DonorAdapter.java
package com.example.serverlogin;
import java.util.ArrayList;
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;
public class DonorAdapter extends ArrayAdapter<Donor> {
ArrayList<Donor> donorList;
LayoutInflater vi;
int Resource;
ViewHolder holder;
public DonorAdapter (Context context , int resource ,ArrayList<Donor> objects)
{
super(context, resource, objects);
vi = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
Resource = resource;
donorList = objects;
}
@Override
public View getView(int position ,View convertView,ViewGroup parent)
{
View v = convertView;
if(v==null)
{
holder = new ViewHolder();
v = vi.inflate(Resource, null);
holder.imageview = (ImageView) v.findViewById(R.id.iv1);
holder.name = (TextView) v.findViewById(R.id.tv1);
holder.phoneNo = (TextView) v.findViewById(R.id.tv2);
holder.remark =(TextView) v.findViewById(R.id.tv3);
holder.id =(TextView) v.findViewById(R.id.tv4);
holder.location=(TextView) v.findViewById(R.id.tv5);
holder.officeLocation =(TextView) v.findViewById(R.id.tv6);
holder.officePhone =(TextView) v.findViewById(R.id.tv7);
holder.resPhone =(TextView) v.findViewById(R.id.tv8);
holder.cellPhone=(TextView) v.findViewById(R.id.tv9);
holder.email =(TextView) v.findViewById(R.id.tv10);
holder.birthdate =(TextView) v.findViewById(R.id.tv11);
holder.gender = (TextView) v.findViewById(R.id.tv12);
holder.lastBloodDonation=(TextView) v.findViewById(R.id.tv13);
}
else{
holder = (ViewHolder) v.getTag();
}
//holder.imageview.setImageResource(R.drawable.ic_launcher);
holder.name.setText(donorList.get(position).getFname()+" "+donorList.get(position).getLname());
String text ="";
/*if(donorList.get(position).getRemark()== null)
text ="";
else
text = donorList.get(position).getRemark();*/
holder.remark.setText(donorList.get(position).getRemark());
holder.id.setText(Integer.toString(donorList.get(position).getDonor_id()));
holder.location.setText(donorList.get(position).getLocation());
holder.officeLocation.setText(donorList.get(position).getOfficeLocation());
holder.officePhone.setText(donorList.get(position).getOfficePhone());
holder.resPhone.setText(donorList.get(position).getResPhone());
holder.cellPhone.setText(donorList.get(position).getCellPhone());
holder.email.setText(donorList.get(position).getEmail());
holder.birthdate.setText(donorList.get(position).getBirthDate());
holder.gender.setText(donorList.get(position).getGender());
holder.lastBloodDonation.setText(donorList.get(position).getLastBlooddonation());
return v;
}
static class ViewHolder {
public ImageView imageview;
public TextView name;
public TextView phoneNo;
public TextView remark;
public TextView id;
public TextView location;
public TextView officeLocation;
public TextView officePhone;
public TextView resPhone;
public TextView cellPhone;
public TextView email;
public TextView birthdate;
public TextView gender;
public TextView lastBloodDonation;
}
}
Donors.java
在logcat的package com.example.serverlogin;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONObject;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;
public class Donors extends ListActivity {
Boolean success = false ;
String url="";
ArrayList <Donor> donorsList = new ArrayList<Donor>();
DonorAdapter adapter;
int count =0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.donors);
try{
ConnectivityManager c =(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo n =c.getActiveNetworkInfo();
if (n!= null && n.isConnected()){
url = "http://192.168.1.100/my/donors.json";
new Background().execute(url);
}
}catch(Exception e){}
adapter = new DonorAdapter(getApplicationContext(),R.layout.row,donorsList);
setListAdapter(adapter);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
// TODO Auto-generated method stub
super.onListItemClick(l, v, position, id);
DisplayToast(donorsList.get(position).getFname());
}
class Background extends AsyncTask<String,Void,Boolean>
{
ProgressDialog dialog;
String check = "";
int count=0;
@Override
protected void onPreExecute()
{
super.onPreExecute();
dialog = new ProgressDialog(Donors.this);
dialog.setMessage("Loading, please wait");
dialog.setTitle("Connecting server");
dialog.show();
dialog.setCancelable(false);
DisplayToast("Calling Background");
}
@Override
protected Boolean doInBackground(String... arg0) {
// TODO Auto-generated method stub
HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet(arg0[0]);
HttpResponse response;
Log.d("url",arg0[0]);
try{
response = httpclient.execute(httpget);
if(response!=null)
{
/*if(response.getStatusLine().getStatusCode()==200)
{
HttpEntity entity = response.getEntity();
if (entity != null)
{
InputStream instream = entity.getContent();
check = convertStreamToString(instream);
if(check.equals(""))
{
check = "no data from file";
}
}
}*/
/*
Gson gson = new Gson();
JsonReader jsonReader = new JsonReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));
jsonReader.beginObject();
Log.d("gson","json");
while (jsonReader.hasNext()) {
//get the element name
String name = jsonReader.nextName();
Log.d("gson2","json");
if (name.equals("success")) {
success = jsonReader.nextBoolean();
}
//if the element name is the list of countries then start the array
else if(name.equals("donors")){
jsonReader.beginArray();
while (jsonReader.hasNext()) {
//parse every element and convert that to a country object
Donor d = gson.fromJson(jsonReader, Donor.class);
Log.d("gson2",d.getAddress());
Log.d("gson2",d.getBirthDate());
Log.d("gson2",d.getBloodGrp());
Log.d("gson2",d.getCellPhone());
Log.d("gson2",d.getCity());
Log.d("gson2",d.getCountry());
Log.d("gson2",d.getEmail());
Log.d("gson2",d.getGender());
Log.d("gson2",d.getLastBlooddonation());
//add the country object to the list
donorsList.add(d);
count++;
Log.d("Inner count",Integer.toString(count));
}
Log.d("In count",Integer.toString(count));
jsonReader.endArray();
}
}
jsonReader.endObject();
jsonReader.close();
*/
//My Logic
HttpEntity entity = response.getEntity();
String data = EntityUtils.toString(entity);
JSONObject jsono = new JSONObject(data);
JSONArray jarray = jsono.getJSONArray("donors");
String t ="";
for (int i = 0; i < jarray.length(); i++) {
JSONObject object = jarray.getJSONObject(i);
Donor d = new Donor();
d.setDonor_id(object.getInt("donor_id"));
d.setFname(object.getString("fname"));
d.setMname(object.getString("mname"));
d.setLname(object.getString("lname"));
d.setAddress(object.getString("address"));
// edit req
d.setLocation(object.getString("location"));
d.setCountry(object.getString("country"));
d.setState(object.getString("state"));
d.setCity(object.getString("city"));
d.setOfficeLocation(object.getString("officeLocation"));
d.setOfficePincode(object.getInt("officePincode"));
d.setOfficePhone(object.getString("officePhone"));
d.setResPhone(object.getString("resPhone"));
d.setCellPhone(object.getString("cellPhone"));
//d.setEmail(object.getString("cellPhone"));
if(object.has("email"))
d.setEmail(object.getString("email"));
d.setBirthDate(object.getString("birthDate"));
d.setBloodGrp(object.getString("bloodGrp"));
d.setGender(object.getString("gender"));
if(object.has("remark"))
d.setRemark(object.getString("remark"));
d.setLastBlooddonation(object.getString("lastBlooddonation"));
donorsList.add(d);
Log.d("do in backgroung",Integer.toString(count++));
}
return true;
}
} catch(Exception e)
{
Log.d("---////////////---", e.toString());
}
return false;
}
public void onPostExecute(Boolean result)
{
dialog.cancel();
adapter.notifyDataSetChanged();
if(result == false)
Toast.makeText(getApplicationContext(), "Unable to fetch data from server", Toast.LENGTH_LONG).show();
//DisplatToast(s);
//btn1.setText(s);
}
}
private void DisplayToast(String msg)
{
Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show();
}
}
和错误是
01-21 02:48:58.553: E/AndroidRuntime(1343): FATAL EXCEPTION: main
01-21 02:48:58.553: E/AndroidRuntime(1343): Process: com.example.serverlogin, PID: 1343
01-21 02:48:58.553: E/AndroidRuntime(1343): java.lang.NullPointerException
01-21 02:48:58.553: E/AndroidRuntime(1343): at com.example.serverlogin.DonorAdapter.getView(DonorAdapter.java:62)
问题出在哪里请有人帮助我。我非常感谢所有人。我是Android新手。
谢谢.....错误消失 – user3651256 2015-01-21 08:19:22
请upvote并标记为正确 – 2015-01-21 08:19:46