Android ListFragment不会填充
所以我正在构建一个应用程序来获取此页面中的数据：http://api.androidhive.info/contacts/并将其放入此片段中的列表视图中。我正在使用ListFragment。我最难将所有内容编译，特别是在oncreateview（）中返回视图时。我收到了这个错误：
我通常可以阅读logcat并了解我需要查看的位置，但我查看第299行，这是一个评论部分......应用程序开始加载进度轮但很快崩溃之前填充之前来自URI的一系列联系人。我对logcat试图告诉我的内容感到困惑。有人可以向我解释我应该采取哪个方向？
这是我的MainActivity：
public class MainActivity extends Activity {
// Within which the entire activity is enclosed
DrawerLayout mDrawerLayout;
// ListView represents Navigation Drawer
ListView mDrawerList;
// ActionBarDrawerToggle indicates the presence of Navigation Drawer in the action bar
ActionBarDrawerToggle mDrawerToggle;
// Title of the action bar
String mTitle="";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = (String) getTitle();
// Getting reference to the DrawerLayout
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.drawer_list);
// Getting reference to the ActionBarDrawerToggle
mDrawerToggle = new ActionBarDrawerToggle( this,
mDrawerLayout,
R.drawable.ic_drawer,
R.string.drawer_open,
R.string.drawer_close){
/** Called when drawer is closed */
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
invalidateOptionsMenu();
}
/** Called when a drawer is opened */
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle("Select Option");
invalidateOptionsMenu();
}
};
// Setting DrawerToggle on DrawerLayout
mDrawerLayout.setDrawerListener(mDrawerToggle);
// Creating an ArrayAdapter to add items to the listview mDrawerList
ArrayAdapter<String> adapter = new ArrayAdapter<String>(
getBaseContext(),
R.layout.drawer_list_item ,
getResources().getStringArray(R.array.options)
);
// Setting the adapter on mDrawerList
mDrawerList.setAdapter(adapter);
// Enabling Home button
getActionBar().setHomeButtonEnabled(true);
// Enabling Up navigation
getActionBar().setDisplayHomeAsUpEnabled(true);
// Setting item click listener for the listview mDrawerList
mDrawerList.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// Getting an array of options
String[] options = getResources().getStringArray(R.array.options);
//Currently selected option
mTitle = options[position];
if(mTitle.equalsIgnoreCase("Home")){
// Creating a fragment object
Fragment fragment = new AppMain();
// Creating a Bundle object
Bundle data = new Bundle();
// Setting the index of the currently selected item of mDrawerList
data.putInt("position", position);
// Setting the position to the fragment
fragment.setArguments(data);
// Getting reference to the FragmentManager
FragmentManager fragmentManager = getFragmentManager();
// Creating a fragment transaction
FragmentTransaction ft = fragmentManager.beginTransaction();
// Adding a fragment to the fragment transaction
ft.replace(R.id.content_frame, fragment);
// Committing the transaction
ft.commit();
// Closing the drawer
mDrawerLayout.closeDrawer(mDrawerList);
}
else if(mTitle.equalsIgnoreCase("Map")){
// Creating a fragment object
Fragment fragment = new MapFragment();
// Creating a Bundle object
Bundle data = new Bundle();
// Setting the index of the currently selected item of mDrawerList
data.putInt("position", position);
// Setting the position to the fragment
fragment.setArguments(data);
// Getting reference to the FragmentManager
FragmentManager fragmentManager = getFragmentManager();
// Creating a fragment transaction
FragmentTransaction ft = fragmentManager.beginTransaction();
// Adding a fragment to the fragment transaction
ft.replace(R.id.content_frame, fragment);
// Committing the transaction
ft.commit();
// Closing the drawer
mDrawerLayout.closeDrawer(mDrawerList);
}
//its possible to create a series of these and then
//initialize objects within the fragments programmably.
//DrawerOptions need to be removed to make things work
else if(mTitle.equalsIgnoreCase("ATO")){
// Creating a fragment object
Fragment fragment = new ATO();
// Creating a Bundle object
Bundle data = new Bundle();
// Setting the index of the currently selected item of mDrawerList
data.putInt("position", position);
// Setting the position to the fragment
fragment.setArguments(data);
// Getting reference to the FragmentManager
FragmentManager fragmentManager = getFragmentManager();
// Creating a fragment transaction
FragmentTransaction ft = fragmentManager.beginTransaction();
// Adding a fragment to the fragment transaction
ft.replace(R.id.content_frame, fragment);
// Committing the transaction
ft.commit();
// Closing the drawer
mDrawerLayout.closeDrawer(mDrawerList);
// Closing the drawer
mDrawerLayout.closeDrawer(mDrawerList);
}
else{
}
}
});
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
mDrawerToggle.syncState();
}
/** Handling the touch event of app icon */
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
return super.onOptionsItemSelected(item);
}
/*
* I commented out this section below because I don't see us using it.
* It does nothing more than show a little button which says "settings"
* in the top right corner of the bar. If you want to enable it, de-comment
* and then look at the main.xml within the menu folder and de-commnent there.
* Also have to go to the Strings.xml file under values and de-comment.
*/
/** Called whenever we call invalidateOptionsMenu() */
@Override
// public boolean onPrepareOptionsMenu(Menu menu) {
// // If the drawer is open, hide action items related to the content view
// boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
//
// menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
// return super.onPrepareOptionsMenu(menu);
// }
//
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
这是我的ATO课程，我遇到了很多麻烦：
public class ATO extends ListFragment {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://api.androidhive.info/contacts/";
// JSON Node names
private static final String TAG_CONTACTS = "contacts";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
private static final String TAG_ADDRESS = "address";
private static final String TAG_GENDER = "gender";
private static final String TAG_PHONE = "phone";
private static final String TAG_PHONE_MOBILE = "mobile";
private static final String TAG_PHONE_HOME = "home";
private static final String TAG_PHONE_OFFICE = "office";
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
// Retrieving the currently selected item number
int position = getArguments().getInt("position");
// List of options
String[] options = getResources().getStringArray(R.array.options);
// Creating view correspoding to the fragment
View v = inflater.inflate(R.layout.ato, container, false);
// Getting reference to the TextView of the Fragment
TextView tv = (TextView) v.findViewById(R.id.textView1);
String words = "Home of the app";
// Setting currently selected river name in the TextView
tv.setText(words);
// Updating the action bar title
getActivity().getActionBar().setTitle(options[position]);
// Calling async task to get json
new GetContacts().execute();
return v;
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(getActivity());
//
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CONTACTS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String email = c.getString(TAG_EMAIL);
String address = c.getString(TAG_ADDRESS);
String gender = c.getString(TAG_GENDER);
// Phone node is JSON Object
JSONObject phone = c.getJSONObject(TAG_PHONE);
String mobile = phone.getString(TAG_PHONE_MOBILE);
String home = phone.getString(TAG_PHONE_HOME);
String office = phone.getString(TAG_PHONE_OFFICE);
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_ID, id);
contact.put(TAG_NAME, name);
contact.put(TAG_EMAIL, email);
contact.put(TAG_PHONE_MOBILE, mobile);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
SimpleAdapter adapter = new SimpleAdapter(getActivity(), contactList,
R.layout.list_item, new String[] { TAG_NAME, TAG_EMAIL,
TAG_PHONE_MOBILE }, new int[] { R.id.name,
R.id.email, R.id.mobile });
setListAdapter(adapter);
}
}
/*
* {
"contacts": [
{
"id": "c200",
"name": "Ravi Tamada",
"email": "ravi@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c201",
"name": "Johnny Depp",
"email": "johnny_depp@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c202",
"name": "Leonardo Dicaprio",
"email": "leonardo_dicaprio@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c203",
"name": "John Wayne",
"email": "john_wayne@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c204",
"name": "Angelina Jolie",
"email": "angelina_jolie@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "female",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c205",
"name": "Dido",
"email": "dido@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "female",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c206",
"name": "Adele",
"email": "adele@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "female",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c207",
"name": "Hugh Jackman",
"email": "hugh_jackman@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c208",
"name": "Will Smith",
"email": "will_smith@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c209",
"name": "Clint Eastwood",
"email": "clint_eastwood@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c2010",
"name": "Barack Obama",
"email": "barack_obama@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c2011",
"name": "Kate Winslet",
"email": "kate_winslet@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "female",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
},
{
"id": "c2012",
"name": "Eminem",
"email": "eminem@gmail.com",
"address": "xx-xx-xxxx,x - street, x - country",
"gender" : "male",
"phone": {
"mobile": "+91 0000000000",
"home": "00 000000",
"office": "00 000000"
}
}
]
}
*/
}
非常感谢任何和所有帮助！
编辑：这是ATO.class的固定类：
package com.example.fratslidemenu;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.zip.Inflater;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ListFragment;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ATO extends ListFragment {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://api.androidhive.info/contacts/";
// JSON Node names
private static final String TAG_CONTACTS = "contacts";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
private static final String TAG_ADDRESS = "address";
private static final String TAG_GENDER = "gender";
private static final String TAG_PHONE = "phone";
private static final String TAG_PHONE_MOBILE = "mobile";
private static final String TAG_PHONE_HOME = "home";
private static final String TAG_PHONE_OFFICE = "office";
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
// Retrieving the currently selected item number
int position = getArguments().getInt("position");
// List of options
String[] options = getResources().getStringArray(R.array.options);
// Creating view correspoding to the fragment
View v = inflater.inflate(R.layout.ato, container, false);
// Updating the action bar title
getActivity().getActionBar().setTitle(options[position]);
// Calling async task to get json
new GetContacts().execute();
return v;
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(getActivity());
//
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CONTACTS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String email = c.getString(TAG_EMAIL);
String address = c.getString(TAG_ADDRESS);
String gender = c.getString(TAG_GENDER);
// Phone node is JSON Object
JSONObject phone = c.getJSONObject(TAG_PHONE);
String mobile = phone.getString(TAG_PHONE_MOBILE);
String home = phone.getString(TAG_PHONE_HOME);
String office = phone.getString(TAG_PHONE_OFFICE);
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_ID, id);
contact.put(TAG_NAME, name);
contact.put(TAG_EMAIL, email);
contact.put(TAG_PHONE_MOBILE, mobile);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
SimpleAdapter adapter = new SimpleAdapter(getActivity(), contactList,
R.layout.list_item, new String[] { TAG_NAME, TAG_EMAIL,
TAG_PHONE_MOBILE }, new int[] { R.id.name,
R.id.email, R.id.mobile });
setListAdapter(adapter);
}
}
}
2 个答案:
答案 0 :(得分：0)
您不会在任何地方初始化contactList。更改声明以创建ArrayList的实例：
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
或在代码使用前将其初始化为代码。
答案 1 :(得分：0)
祝你新年快乐2014年
请实例化声明的
ArrayList<HashMap<String, String>> contactList;
如果您检查了您的代码，则忘记添加行
contactList = new ArrayList<HashMap<String, String>>();
在使用之前请有一个特定的对象。希望它能解决你的问题
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