我正在使用Listview来传递后端的值。我的问题是每当我运行我的代码时，我总是在getcount方法中得到arraylist的大小为零。 我有搜索但没有正确理解
任何人都可以帮助我吗朋友
我的Listview适配器类是
private class ListViewAdaptar extends BaseAdapter {
private LayoutInflater _inflater;
private List<Student_Location_Model> _list;
private Context _context;
String enroll_no;
String driver_id, hash;
//CharSequence[] show_data = {"Home Pick", "Home Drop", "School Pick", "School Drop", "Absent", "Other"};
CharSequence[] show_data1 = {"School Drop", "School Pick", "Home Drop", "Absent"};
String cat = "notselected";
String changed_cat, remark = "remark";
public ListViewAdaptar(Activity context, List<Student_Location_Model> lst) {
if (context != null && lst != null) {
this._context = context;
_list = lst;
_inflater = LayoutInflater.from(context);
}
}
@Override
public int getCount() {
return _list.size();
}
@Override
public Object getItem(int i) {
return _list.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public int getViewTypeCount() {
return getCount();
}
@Override
public View getView(final int position, View listItems, ViewGroup parent) {
final ViewHolder holder;
SharedPreferences sharedPreferences = _context.getSharedPreferences(_context.getString(R.string.BUS_DETAILS), Context.MODE_PRIVATE);
hash = sharedPreferences.getString(_context.getString(R.string.HASH), "");
driver_id = sharedPreferences.getString(_context.getString(R.string.DRIVER_ID), "");
// if (listItems == null) {
listItems = _inflater.inflate(R.layout.listview_adapter_design, null);
holder = new ViewHolder();
holder.txt_loc_id = (TextView) listItems.findViewById(R.id.location_id);
holder.txt_enroll_no = (TextView) listItems.findViewById(R.id.textview_student_enroll);
holder.txt_student_name = (TextView) listItems.findViewById(R.id.textview_student_name);
holder.select_data = (TextView) listItems.findViewById(R.id.select_data);
holder.checkbox_select_one = (CheckBox) listItems.findViewById(R.id.checkbox_select_one);
final Student_Location_Model locationModel = _list.get(position);
holder.txt_student_name.setText(locationModel.getStudent_name());
holder.txt_enroll_no.setText(locationModel.getEnroll_num());
holder.txt_loc_id.setText(locationModel.getLocation_name());
holder.checkbox_select_one.setChecked(locationModel.isItemCheck());
holder.select_data.setText(locationModel.getStudent_track_status());
holder.checkbox_select_one.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (((CheckBox) view).isChecked()) {
Student_Location_Model model = _list.get(position);
model.setItemCheck(true);
notifyDataSetChanged();
} else {
Student_Location_Model model = _list.get(position);
model.setItemCheck(false);
notifyDataSetChanged();
}
String selected_student = "";
for (int i = 0; i < _list.size(); i++) {
Student_Location_Model locationModel1 = _list.get(i);
if (locationModel1.isItemCheck()) {
selected_student = locationModel1.getEnroll_num() + " , " + selected_student;
}
}
checkbox_select_all.setChecked(false);
Log.e("String of Students :- ", selected_student);
selected_enroll_no.setText(selected_student);
}
});
if (holder.checkbox_select_one.isChecked()) {
SharedPreferences preferences = New_Student_Details_Location.this.getSharedPreferences(getString(R.string.LATEST_SELECTION), MODE_PRIVATE);
String new_selection = preferences.getString(getString(R.string.SELECTED_VALUE), "");
holder.select_data.setText(new_selection);
if (new_selection.equalsIgnoreCase("")) {
holder.select_data.setText("Select");
}
}
holder.select_data.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final AlertDialog.Builder builder;
builder = new AlertDialog.Builder(_context);
builder.setTitle("Select One");
builder.setSingleChoiceItems(show_data1, -1, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
switch (i) {
case 0:
cat = (String) show_data1[i];
break;
case 1:
cat = (String) show_data1[i];
//holder.select_data.setText(cat);
break;
case 2:
cat = (String) show_data1[i];
// holder.select_data.setText(cat);
break;
case 3:
cat = (String) show_data1[i];
// holder.select_data.setText(cat);
break;
}
}
});
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
/* if (cat.equalsIgnoreCase("Home Pick")) {
holder.select_data.setText(cat);
//newcat = holder.select_data.getText().toString();
changed_cat = cat.replace("Home Pick", "home_pickup");
enroll_no = holder.txt_enroll_no.getText().toString();
Toast.makeText(_context, "You have Selected " + cat, Toast.LENGTH_SHORT).show();
new BackgroundJob().execute();
cat = "notselected";
}*/
if (cat.equalsIgnoreCase("Home Drop")) {
holder.select_data.setText(cat);
//newcat = holder.select_data.getText().toString();
changed_cat = cat.replace("Home Drop", "home_drop");
enroll_no = holder.txt_enroll_no.getText().toString();
StyleableToast.makeText(_context, "You Selected " + cat, Toast.LENGTH_SHORT, R.style.StyledToast).show();
new BackgroundJob().execute();
cat = "notselected";
} else if (cat.equalsIgnoreCase("School Pick")) {
holder.select_data.setText(cat);
//newcat = holder.select_data.getText().toString();
changed_cat = cat.replace("School Pick", "school_pickup");
enroll_no = holder.txt_enroll_no.getText().toString();
StyleableToast.makeText(_context, "You Selected " + cat, Toast.LENGTH_SHORT, R.style.StyledToast).show();
new BackgroundJob().execute();
cat = "notselected";
} else if (cat.equalsIgnoreCase("School Drop")) {
holder.select_data.setText(cat);
//newcat = holder.select_data.getText().toString();
changed_cat = cat.replace("School Drop", "school_drop");
enroll_no = holder.txt_enroll_no.getText().toString();
StyleableToast.makeText(_context, "You Selected " + cat, Toast.LENGTH_SHORT, R.style.StyledToast).show();
new BackgroundJob().execute();
cat = "notselected";
} else if (cat.equalsIgnoreCase("Absent")) {
holder.select_data.setText(cat);
//newcat = holder.select_data.getText().toString();
changed_cat = cat.replace("Absent", "absent");
enroll_no = holder.txt_enroll_no.getText().toString();
StyleableToast.makeText(_context, "You Selected " + cat, Toast.LENGTH_SHORT, R.style.StyledToast).show();
new BackgroundJob().execute();
cat = "notselected";
}
/* else if (cat.equalsIgnoreCase("Other")) {
holder.select_data.setText(cat);
//newcat = holder.select_data.getText().toString();
changed_cat = cat.replace("Other", "other");
enroll_no = holder.txt_enroll_no.getText().toString();
AlertDialog.Builder builder1 = new AlertDialog.Builder(_context);
final EditText edt_remark = new EditText(_context);
builder1.setTitle("Reason");
builder1.setMessage("Please enter a valid reason");
builder1.setView(edt_remark);
builder1.setPositiveButton("SAVE", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
remark = edt_remark.getText().toString();
new BackgroundJob().execute();
}
});
builder1.show();
cat = "notselected";
}*/
else if (cat.equalsIgnoreCase("notselected")) {
StyleableToast.makeText(_context, "Please Select One", Toast.LENGTH_SHORT, R.style.StyledToast_one).show();
}
}
});
builder.setCancelable(false);
builder.show();
}
});
listItems.setTag(holder);
listItems.setTag(R.id.checkbox_select_one, holder.checkbox_select_one);
holder.checkbox_select_one.setTag(position);
return listItems;
}
@Override
public int getItemViewType(int position) {
return position;
}
private class ViewHolder {
TextView txt_loc_id;
TextView txt_enroll_no;
TextView txt_student_name;
TextView select_data;
CheckBox checkbox_select_one;
}
private class BackgroundJob extends AsyncTask<String, String, String> {
@Override
protected String doInBackground(String... strings) {
return JsonParser.makeHttpUrlConnectionRequest(API.Update_Student_Details, dataparams());
}
private List<NameValuePair> dataparams() {
ArrayList<NameValuePair> parameters = new ArrayList<>();
parameters.add(new BasicNameValuePair("hash", hash));
parameters.add(new BasicNameValuePair("driver_id", driver_id));
parameters.add(new BasicNameValuePair("enroll_num", enroll_no));
parameters.add(new BasicNameValuePair("track_status", changed_cat));
parameters.add(new BasicNameValuePair("remark", remark));
Log.e("Parematers", ":" + parameters);
return parameters;
}
@Override
protected void onPostExecute(String httpResponse) {
JSONObject responseParameters;
if (httpResponse == null) {
StyleableToast.makeText(_context, "No Internet Connection", Toast.LENGTH_SHORT, R.style.StyledToast_one).show();
} else {
try {
responseParameters = new JSONObject(httpResponse);
String status = responseParameters.getString("status");
if (status.equalsIgnoreCase("success")) {
StyleableToast.makeText(_context, "Saved Successfully.", Toast.LENGTH_SHORT, R.style.StyledToast).show();
} else {
StyleableToast.makeText(_context, "Status Already Updated", Toast.LENGTH_SHORT, R.style.StyledToast_one).show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
}
我的用于设置适配器的类
public class Student_Location_Model {
String location_id, location_name, enroll_num, student_name, student_track_status;
boolean isItemCheck;
public Student_Location_Model(String location_id, String location_name,
String enroll_num, String student_name,
boolean isItemCheck, String student_track_status) {
this.location_id = location_id;
this.location_name = location_name;
this.enroll_num = enroll_num;
this.student_name = student_name;
this.isItemCheck = isItemCheck;
this.student_track_status = student_track_status;
}
public String getStudent_track_status() {
return student_track_status;
}
public void setStudent_track_status(String student_track_status) {
this.student_track_status = student_track_status;
}
public boolean isItemCheck() {
return isItemCheck;
}
public void setItemCheck(boolean itemCheck) {
isItemCheck = itemCheck;
}
public String getLocation_id() {
return location_id;
}
public void setLocation_id(String location_id) {
this.location_id = location_id;
}
public String getLocation_name() {
return location_name;
}
public void setLocation_name(String location_name) {
this.location_name = location_name;
}
public String getEnroll_num() {
return enroll_num;
}
public void setEnroll_num(String enroll_num) {
this.enroll_num = enroll_num;
}
public String getStudent_name() {
return student_name;
}
public void setStudent_name(String student_name) {
this.student_name = student_name;
}
}