问题
MessagesActivity.java
package org.example.fbapp;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.facebook.android.AsyncFacebookRunner;
import com.facebook.android.Facebook;
import com.facebook.android.FacebookError;
import com.facebook.android.AsyncFacebookRunner.RequestListener;
import android.app.ListActivity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
public class MessagesActivity extends ListActivity {
// Your Facebook APP ID
private static String APP_ID = "549603678442054";
ListAdapter adapter;
// JSON Node names
private static final String TAG_DATA = "data";
private static final String TAG_MESSAGE = "message";
// data JSONArray
JSONArray data = null;
// Instance of Facebook Class
@SuppressWarnings("deprecation")
private Facebook facebook = new Facebook(APP_ID);
@SuppressWarnings("deprecation")
private AsyncFacebookRunner mAsyncRunner;
String FILENAME = "AndroidSSO_data";
private SharedPreferences mPrefs;
// Hashmap for ListView
ArrayList<HashMap<String, String>> messages = new ArrayList<HashMap<String, String>>();
private ListView lv;
ListView mylistview;
ArrayList<String> array_months;
ArrayAdapter<String> listAdapter;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.contacts_view);
mAsyncRunner = new AsyncFacebookRunner(facebook);
ListAdapter adapter = createAdapter();
setListAdapter(adapter);
}
/**
* Creates and returns a list adapter for the current list activity
*
* @return
*/
@SuppressWarnings("deprecation")
protected ListAdapter createAdapter()
{
mAsyncRunner.request("203153109726651/feed", new RequestListener() {
@Override
public void onComplete(String response, Object state) {
Log.d("GET POSTS", response);
String json = response;
try {
// Facebook Profile JSON data
JSONObject obj = new JSONObject(json);
JSONArray finalObj = obj.getJSONArray("data");
array_months = new ArrayList<String>();
for (int i = 0; i < finalObj.length(); i++) {
final String message = finalObj.getJSONObject(i)
.getString("message");
array_months.add(message);
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Name: " + message, Toast.LENGTH_LONG)
.show();
}
});
}
// Create a simple array adapter (of type string) with the test values
//ListAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, adapter);
adapter = new ArrayAdapter<String>(MessagesActivity.this,
android.R.layout.simple_list_item_1, array_months);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onIOException(IOException e, Object state) {
}
@Override
public void onFileNotFoundException(FileNotFoundException e,
Object state) {
}
@Override
public void onMalformedURLException(MalformedURLException e,
Object state) {
}
@Override
public void onFacebookError(FacebookError e, Object state) {
}
});
//setListAdapter(listAdapter);
return adapter;
}
}
FBAppActivity.java
package org.example.fbapp;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import com.facebook.android.AsyncFacebookRunner;
import com.facebook.android.AsyncFacebookRunner.RequestListener;
import com.facebook.android.DialogError;
import com.facebook.android.Facebook;
import com.facebook.android.Facebook.DialogListener;
import com.facebook.android.FacebookError;
@SuppressWarnings("deprecation")
public class FBAppActivity extends Activity {
// Your Facebook APP ID
private static String APP_ID = "549603678442054";
// JSON Node names
private static final String TAG_DATA = "data";
private static final String TAG_MESSAGE = "message";
// data JSONArray
JSONArray data = null;
// Instance of Facebook Class
private Facebook facebook = new Facebook(APP_ID);
private AsyncFacebookRunner mAsyncRunner;
String FILENAME = "AndroidSSO_data";
private SharedPreferences mPrefs;
// Hashmap for ListView
ArrayList<HashMap<String, String>> messages = new ArrayList<HashMap<String, String>>();
private ListView lv;
// Buttons
Button btnFbLogin;
Button btnFbGetProfile;
Button btnPostToWall;
Button btnShowAccessTokens;
Button btnFbLogout;
Button btnGetPost;
@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fbapp);
// facebook = new Facebook(APP_ID);
btnFbLogin = (Button) findViewById(R.id.btn_fblogin);
btnFbGetProfile = (Button) findViewById(R.id.btn_get_profile);
btnPostToWall = (Button) findViewById(R.id.btn_fb_post_to_wall);
btnShowAccessTokens = (Button) findViewById(R.id.btn_show_access_tokens);
btnFbLogout = (Button) findViewById(R.id.btn_logout);
btnGetPost = (Button) findViewById(R.id.btn_group_posts);
mAsyncRunner = new AsyncFacebookRunner(facebook);
/**
* Login button Click event
* */
btnFbLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d("Image Button", "button Clicked");
loginToFacebook();
}
});
/**
* Logout button Click event
* */
btnFbLogout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d("Logout Button", "button Clicked");
logoutFromFacebook();
}
});
/**
* Getting facebook Profile info
* */
btnFbGetProfile.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getProfileInformation();
}
});
/**
* Posting to Facebook Wall
* */
btnPostToWall.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
postToWall();
}
});
/**
* Get Posts from Group
* */
btnGetPost.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// getGroupPosts();
//getGPosts();
startActivity(new Intent(FBAppActivity.this, MessagesActivity.class));
}
});
/**
* Showing Access Tokens
* */
btnShowAccessTokens.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
showAccessTokens();
}
});
}
/**
* Function to login into facebook
* */
@SuppressWarnings("deprecation")
public void loginToFacebook() {
mPrefs = getPreferences(MODE_PRIVATE);
String access_token = mPrefs.getString("access_token", null);
long expires = mPrefs.getLong("access_expires", 0);
if (access_token != null) {
facebook.setAccessToken(access_token);
btnFbLogin.setVisibility(View.INVISIBLE);
// Making get profile button visible
btnFbGetProfile.setVisibility(View.VISIBLE);
// Making post to wall visible
btnPostToWall.setVisibility(View.VISIBLE);
// Making show access tokens button visible
btnShowAccessTokens.setVisibility(View.VISIBLE);
// Making logout button visible
btnFbLogout.setVisibility(View.VISIBLE);
// Making group posts button visible
btnGetPost.setVisibility(View.VISIBLE);
Log.d("FB Sessions", "" + facebook.isSessionValid());
}
if (expires != 0) {
facebook.setAccessExpires(expires);
}
if (!facebook.isSessionValid()) {
facebook.authorize(this, new String[] { "email", "publish_stream",
"user_groups" }, new DialogListener() {
@Override
public void onCancel() {
// Function to handle cancel event
}
@Override
public void onComplete(Bundle values) {
// Function to handle complete event
// Edit Preferences and update facebook acess_token
SharedPreferences.Editor editor = mPrefs.edit();
editor.putString("access_token", facebook.getAccessToken());
editor.putLong("access_expires",
facebook.getAccessExpires());
editor.commit();
// Making Login button invisible
btnFbLogin.setVisibility(View.INVISIBLE);
// Making logout Button visible
btnFbGetProfile.setVisibility(View.VISIBLE);
// Making post to wall visible
btnPostToWall.setVisibility(View.VISIBLE);
// Making show access tokens button visible
btnShowAccessTokens.setVisibility(View.VISIBLE);
// Making logout button visible
btnFbLogout.setVisibility(View.VISIBLE);
// Making group posts button visible
btnGetPost.setVisibility(View.VISIBLE);
}
@Override
public void onError(DialogError error) {
// Function to handle error
}
@Override
public void onFacebookError(FacebookError fberror) {
// Function to handle Facebook errors
}
});
}
}
@SuppressWarnings("deprecation")
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
facebook.authorizeCallback(requestCode, resultCode, data);
}
/**
* Get Profile information by making request to Facebook Graph API
* */
@SuppressWarnings("deprecation")
public void getProfileInformation() {
mAsyncRunner.request("me", new RequestListener() {
@Override
public void onComplete(String response, Object state) {
Log.d("Profile", response);
String json = response;
try {
// Facebook Profile JSON data
JSONObject profile = new JSONObject(json);
// getting name of the user
final String name = profile.getString("name");
// getting email of the user
final String email = profile.getString("email");
JSONObject birthday = profile.getJSONObject("location");
final String location = birthday.getString("name");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(
getApplicationContext(),
"Name: " + name + "\nEmail: " + email
+ "\nLocation: " + location,
Toast.LENGTH_LONG).show();
}
});
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onIOException(IOException e, Object state) {
}
@Override
public void onFileNotFoundException(FileNotFoundException e,
Object state) {
}
@Override
public void onMalformedURLException(MalformedURLException e,
Object state) {
}
@Override
public void onFacebookError(FacebookError e, Object state) {
}
});
}
/**
* Get Group Posts by making request to Facebook Graph API
* */
@SuppressWarnings("deprecation")
public void getGPosts() {
mAsyncRunner.request("203153109726651/feed", new RequestListener() {
@Override
public void onComplete(String response, Object state) {
Log.d("GET POSTS", response);
String json = response;
try {
// Facebook Profile JSON data
JSONObject obj = new JSONObject(json);
JSONArray finalObj = obj.getJSONArray("data");
for (int i = 0; i < finalObj.length(); i++) {
final String message = finalObj.getJSONObject(i)
.getString("message");
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_MESSAGE, message);
// adding HashList to ArrayList
messages.add(map);
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Name: " + message, Toast.LENGTH_LONG)
.show();
}
});
}
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onIOException(IOException e, Object state) {
}
@Override
public void onFileNotFoundException(FileNotFoundException e,
Object state) {
}
@Override
public void onMalformedURLException(MalformedURLException e,
Object state) {
}
@Override
public void onFacebookError(FacebookError e, Object state) {
}
});
ListAdapter adapter = new SimpleAdapter(FBAppActivity.this, messages,
R.layout.list_item,
new String[] { TAG_MESSAGE }, new int[] {
R.id.name });
//FBAppActivity.this.setListAdapter(adapter);
}
/**
* Function to post to facebook wall
* */
@SuppressWarnings("deprecation")
public void postToWall() {
// post on user's wall.
facebook.dialog(this, "feed", new DialogListener() {
@Override
public void onFacebookError(FacebookError e) {
}
@Override
public void onError(DialogError e) {
}
@Override
public void onComplete(Bundle values) {
}
@Override
public void onCancel() {
}
});
}
/**
* Function to show Access Tokens
* */
@SuppressWarnings("deprecation")
public void showAccessTokens() {
String access_token = facebook.getAccessToken();
Toast.makeText(getApplicationContext(),
"Access Token: " + access_token, Toast.LENGTH_LONG).show();
}
/**
* Function to Logout user from Facebook
* */
@SuppressWarnings("deprecation")
public void logoutFromFacebook() {
mAsyncRunner.logout(this, new RequestListener() {
@Override
public void onComplete(String response, Object state) {
Log.d("Logout from Facebook", response);
if (Boolean.parseBoolean(response) == true) {
runOnUiThread(new Runnable() {
@Override
public void run() {
// make Login button visible
btnFbLogin.setVisibility(View.VISIBLE);
// making all remaining buttons invisible
btnFbGetProfile.setVisibility(View.INVISIBLE);
btnPostToWall.setVisibility(View.INVISIBLE);
btnShowAccessTokens.setVisibility(View.INVISIBLE);
btnFbLogout.setVisibility(View.INVISIBLE);
btnGetPost.setVisibility(View.INVISIBLE);
}
});
}
}
@Override
public void onIOException(IOException e, Object state) {
}
@Override
public void onFileNotFoundException(FileNotFoundException e,
Object state) {
}
@Override
public void onMalformedURLException(MalformedURLException e,
Object state) {
}
@Override
public void onFacebookError(FacebookError e, Object state) {
}
});
}
/*
* @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the
* menu; this adds items to the action bar if it is present.
* getMenuInflater().inflate(R.menu.fbapp, menu); return true; }
*/
}
When i click on the button, the ListView opens but with no data i.e. Empty set.
Contacts_View.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView android:id="@android:id/empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Empty set"
/>
</LinearLayout>
What i mean here is that both the functions are identical.getGPosts() is called in the FBAppActivity whereas the createAdapter() is called in MessagesActivity.getGPosts() works but createAdapter() does not. Kindly help me understand why is this happening.
Basically i am trying to import posts from a facebook group. My Toast object is working fine from the getGPosts() [it is in the FBAppActivity class] function. This function getGPosts() is called on the button click.I verified that i am getting the data using the Toast object. Now i want to populate the data to a ListView. Which i am unable to do. I have tried various methods, but none has worked out for me.
回答1:
Because you're calling the setListAdapter(adapter) for implicit (Activity's) ListView in the onCreate(Bundle savedInstanceState) method and in the getGPosts() method you reference the correct (visible) ListView.
Simply change the mentioned call in the onCreate(Bundle savedInstanceState) method to:
myListView = getListView();
myListView.setAdapter(adapter);
And you should be fine! Good luck!
P.S. This solution will work if your ListActivity follows the following requirement:
your own view MUST contain a ListView object with the id "@android:id/list"
from Google's documentation
回答2:
As I see you are extending ListActivity. So below code must throw a NPE.
lv = (ListView)findViewById(R.id.list);
lv.setAdapter(adapter);
You should use below code at onComplete method instead;
setListAdapter(adapter);
or
getListView().setAdapter(adapter);
来源：https://stackoverflow.com/questions/19623353/listview-loads-with-no-data-android