这是我写的代码： -
package com.example.hp.applood;
import java.io.IOException;
import java.util.ArrayList;
public class aa extends AppCompatActivity {
int CONNECTION_TIMEOUT = 1000 * 15;
ProgressDialog progressDialog;
String SERVER_ADDRESS = "http://xxxxxxxxx/";
public aa(Context context) {
progressDialog = new ProgressDialog(context);
progressDialog.setCancelable(false);
progressDialog.setTitle("Processing..");
progressDialog.setMessage("Please wait");
}
ArrayList<User> userlist;
MyCustomAdapter dataAdapter = null;
Spinner s11 = (Spinner) findViewById(R.id.spinner);
Spinner s2 = (Spinner) findViewById(R.id.spinner2);
String bloodd = s11.getSelectedItem().toString();
String loc = s2.getSelectedItem().toString();
public void storeUserDataInBackground(User user, GetUserCallback userCallback) {
progressDialog.show();
new aaAsyncTask(user, userCallback).execute();
}
public void fetchUserDataInBackground(User user, GetUserCallback callback) {
progressDialog.show();
new aaAsyncTask(user, callback).execute();
}
public class aaAsyncTask extends AsyncTask<Void, Void, ArrayList<User>> {
User user;
GetUserCallback userCallback;
public aaAsyncTask(User user, GetUserCallback usercallback) {
this.user = user;
this.userCallback = usercallback;
}
protected ArrayList<User> doInBackground(Void... params) {
ArrayList<NameValuePair> dataToSend = new ArrayList<>();
dataToSend.add(new BasicNameValuePair("bloodtype", bloodd));
dataToSend.add(new BasicNameValuePair("location", loc));
HttpParams httpRequestParams = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpRequestParams, CONNECTION_TIMEOUT);
HttpConnectionParams.setSoTimeout(httpRequestParams, CONNECTION_TIMEOUT);
HttpClient client = new DefaultHttpClient(httpRequestParams);
HttpPost post = new HttpPost(SERVER_ADDRESS + "/Search.php");
ArrayList<User> userlist = null;
User returnedUser=null;
try {
post.setEntity(new UrlEncodedFormEntity(dataToSend));
HttpResponse httpResponse = client.execute(post);
HttpEntity entity = httpResponse.getEntity();
String result = EntityUtils.toString(entity);
JSONObject jObject = new JSONObject(result);
if (jObject.length() == 0) {
userlist = null;
Context context = getApplicationContext();
CharSequence text = "no available donor!";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
} else {
String resultt = EntityUtils.toString(entity);
JSONArray jsonArray = new JSONArray(resultt);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String fname = jsonObject.getString("firstname");
String lname = jsonObject.getString("lastname");
String blood = jsonObject.getString("blood");
String location = jsonObject.getString("location");
String email = jsonObject.getString("email");
String age = jsonObject.getString("age");
String password = jsonObject.getString("password");
String phone = jsonObject.getString("phone");
int agee = Integer.parseInt(age);
int phonee = Integer.parseInt(phone);
returnedUser = new User(fname, lname, blood, location, email, password, agee, phonee);
userlist.add(returnedUser);
}
}
} catch (Exception e) {
e.printStackTrace();
}
protected void onPostExecute(String content) {
progressDialog.dismiss();
displayCountryList(content);
}
}
}
private void displayCountryList(String response){
try {
dataAdapter = new MyCustomAdapter(this,
R.layout.listv, userlist);
ListView listView = (ListView) findViewById(R.id.listView);
listView.setAdapter(dataAdapter);
listView.setTextFilterEnabled(true);
}
catch (Exception e) {
e.printStackTrace();
}
}
protected void sendSMSMessage() {
Log.i("Send SMS", "");
TextView phone = (TextView)findViewById(R.id.textView33);
TextView name = (TextView)findViewById(R.id.textView31);
String aname= name.toString();
String txtMessage = "hello my name is "+aname+"and i need blood if you can donnate please fill the form in the app and call me";
String phoneNo = phone.getText().toString();
String message = txtMessage;
try {
SmsManager smsManager = SmsManager.getDefault();
smsManager.sendTextMessage(phoneNo, null, message, null, null);
Toast.makeText(getApplicationContext(), "SMS sent.", Toast.LENGTH_LONG).show();
}
catch (Exception e) {
Toast.makeText(getApplicationContext(), "SMS failed, please try again.", Toast.LENGTH_LONG).show();
e.printStackTrace();
}
}
class MyCustomAdapter extends ArrayAdapter<User> {
private ArrayList<User> userlist;
public MyCustomAdapter(Context context, int textViewResourceId,
ArrayList<User> userlist) {
super(context, textViewResourceId, userlist);
this.userlist = new ArrayList<User>();
this.userlist.addAll(userlist);
}
private class ViewHolder {
TextView name;
TextView phone;
TextView email;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
Log.v("ConvertView", String.valueOf(position));
if (convertView == null) {
LayoutInflater vi = (LayoutInflater)getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.listv, null);
holder = new ViewHolder();
holder.name = (TextView) convertView.findViewById(R.id.textView31);
holder.phone = (TextView) convertView.findViewById(R.id.textView33);
holder.email = (TextView) convertView.findViewById(R.id.textView34);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
User user = userlist.get(position);
holder.name.setText(user.getFirstname());
holder.phone.setText(user.getPhone());
holder.email.setText(user.getEmail());
return convertView;
}
}
}
在这个课程中，我试图获得一个ArrayList<User>用户是我创建的类，并用用户填充列表视图，但是应用程序总是崩溃，并且存储和获取的方法是2不使用后台用户，然后获取系统服务未解决问题请帮忙。
答案 0 :(得分：1)
哦不..你是想在doInBackground（）旁边显示吐司信息吗？请检查您的代码
Toast toast = Toast.makeText(context, text, duration);
toast.show();
所以这是Android的规则。您无法从后台线程触摸UI线程。 Toast消息出现在UI线程中，导致崩溃。请删除它。
答案 1 :(得分：0)
我认为问题在于响应Json尝试在onCreate（）中初始化 userList ;或者在将userList提供给listView之前添加null检查。
始终检查响应代码
if(httpResponce.getStatusLine().getStatusCode()==200){
HttpEntity entity = httpResponse.getEntity();
String result = EntityUtils.toString(entity);
}
HttpEntity entity = httpResponse.getEntity();
String result = EntityUtils.toString(entity);
希望这会有所帮助：）