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朋友們，我有一個按鈕facebook集成錯誤點擊，它總是返回NullPointerException異常，我不知道爲什麼？請建議我正確的結果......Facebook的整合在Android的
代碼：
package com.ex.softZilla;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.ImageButton;
import android.util.AttributeSet;
import android.graphics.Color;
import com.ex.softZilla.BaseRequestListener;
import com.ex.softZilla.SessionEvents.AuthListener;
import com.ex.softZilla.SessionEvents.LogoutListener;
import com.ex.softZilla.Facebook.DialogListener;
public class SettingActivity extends Activity{
final String APP_ID = "172619129456913";
String bytesSent;
HttpClient httpclient;
int count1;
// List with parameters and their values
List<NameValuePair> nameValuePairs;
LoginButton mLoginButton;
TextView mText;
Facebook mFacebook;
AsyncFacebookRunner mAsyncRunner;
AlertDialog.Builder alertNetwork;
private Facebook mFb;
private Handler mHandler;
private SessionListener mSessionListener = new SessionListener();
private String[] mPermissions;
private Activity mActivity;
Button btn_facebook;
Button btn_twitter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.more_setting);
btn_facebook = (Button)findViewById(R.id.btn_More_setting_facebook);
btn_twitter = (Button)findViewById(R.id.btn_more_setting_twitter);
btn_facebook.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
alertNetwork = new AlertDialog.Builder(SettingActivity.this);
ConnectivityManager connMgr = (ConnectivityManager)
SettingActivity.this.getSystemService(getApplicationContext().CONNECTIVITY_SERVICE);
/* final android.net.NetworkInfo wifi =
connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
final android.net.NetworkInfo mobile =
connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);*/
/*if(!wifi.isAvailable()||mobile.isAvailable()){
alertNetwork.setTitle("Network Error.");
alertNetwork.setMessage("Please check your network connection.");
alertNetwork.setNeutralButton("Ok",null);
alertNetwork.show();
this.onDestroy();
}*/
if (APP_ID == null) {
Util.showAlert(SettingActivity.this, "Warning", "Facebook Applicaton ID must be " +
"specified before running this example: see Example.java");
}
Display display = getWindowManager().getDefaultDisplay();
int width = display.getWidth();
int height = display.getHeight();
System.out.println("Width:"+width);
System.out.println("Height:"+height);
// setContentView(R.layout.facebookviewlarge);
mText = (TextView) SettingActivity.this.findViewById(R.id.txt);
mFacebook = new Facebook(APP_ID);
mAsyncRunner = new AsyncFacebookRunner(mFacebook);
SessionStore.restore(mFacebook, SettingActivity.this);
SessionEvents.addAuthListener(new SampleAuthListener());
SessionEvents.addLogoutListener(new SampleLogoutListener());
//login class is calling here
// mLoginButton.init(SettingActivity.this, mFacebook);
//mLoginButton.
if (mFb.isSessionValid()) {
SessionEvents.onLogoutBegin();
AsyncFacebookRunner asyncRunner = new AsyncFacebookRunner(mFb);
asyncRunner.logout(getApplicationContext(), new LogoutRequestListener());
} else {
mFb.authorize(mActivity, mPermissions,
new LoginDialogListener());
}
}
/*Intent intent = new Intent(SettingActivity.this,Example.class);
startActivity(intent);*/
});
btn_twitter.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent(SettingActivity.this,TwitterViewController.class);
startActivity(intent);
}
});
}
class SampleAuthListener implements AuthListener {
public void onAuthSucceed() {
mText.setText("You have logged in! ");
mFacebook.dialog(SettingActivity.this, "feed", new SampleDialogListener());
}
public void onAuthFail(String error) {
mText.setText("Login Failed: " + error);
}
}
class SampleLogoutListener implements LogoutListener {
public void onLogoutBegin() {
mText.setText("Logging out...");
}
public void onLogoutFinish() {
mText.setText("You have logged out! ");
}
}
class SampleRequestListener extends BaseRequestListener {
public void onComplete(final String response) {
try {
// process the response here: executed in background thread
Log.d("Facebook-Example", "Response: " + response.toString());
JSONObject json = Util.parseJson(response);
final String name = json.getString("name");
// then post the processed result back to the UI thread
// if we do not do this, an runtime exception will be generated
// e.g. "CalledFromWrongThreadException: Only the original
// thread that created a view hierarchy can touch its views."
SettingActivity.this.runOnUiThread(new Runnable() {
public void run() {
mText.setText("Hello there, " + name + "!");
}
});
} catch (JSONException e) {
Log.w("Facebook-Example", "JSON Error in response");
} catch (FacebookError e) {
Log.w("Facebook-Example", "Facebook Error: " + e.getMessage());
}
}
}
class WallPostRequestListener extends BaseRequestListener {
public void onComplete(final String response) {
Log.d("Facebook-Example", "Got response: " + response);
String message = "<empty>";
try {
JSONObject json = Util.parseJson(response);
message = json.getString("message");
} catch (JSONException e) {
Log.w("Facebook-Example", "JSON Error in response");
} catch (FacebookError e) {
Log.w("Facebook-Example", "Facebook Error: " + e.getMessage());
}
final String text = "Your Wall Post: " + message;
SettingActivity.this.runOnUiThread(new Runnable() {
public void run() {
mText.setText(text);
//postTotalShare();
}
});
}
}
class SampleDialogListener extends BaseDialogListener {
public void onComplete(Bundle values) {
final String postId = values.getString("post_id");
if (postId != null) {
Log.d("Facebook-Example", "Dialog Success! post_id=" + postId);
mAsyncRunner.request(postId, new WallPostRequestListener());
}
}
}
class SessionListener implements AuthListener, LogoutListener {
public void onAuthSucceed() {
//setImageResource(R.drawable.logout_button);
SessionStore.save(mFb, getApplicationContext());
}
public void onAuthFail(String error) {
}
public void onLogoutBegin() {
}
public void onLogoutFinish() {
SessionStore.clear(getApplicationContext());
//setImageResource(R.drawable.login_button);
}
}
public void init(final Activity activity, final Facebook fb) {
init(activity, fb, new String[] {});
}
public void init(final Activity activity, final Facebook fb,
final String[] permissions) {
mActivity = activity;
mFb = fb;
mPermissions = permissions;
mHandler = new Handler();
// setBackgroundColor(Color.TRANSPARENT);
// setAdjustViewBounds(true);
//setImageResource(fb.isSessionValid() ?
//R.drawable.logout_button :
//R.drawable.login_button);
//drawableStateChanged();
SessionEvents.addAuthListener(mSessionListener);
SessionEvents.addLogoutListener(mSessionListener);
}
private final class LoginDialogListener implements DialogListener {
public void onComplete(Bundle values) {
SessionEvents.onLoginSuccess();
}
public void onFacebookError(FacebookError error) {
SessionEvents.onLoginError(error.getMessage());
}
public void onError(DialogError error) {
SessionEvents.onLoginError(error.getMessage());
}
public void onCancel() {
SessionEvents.onLoginError("Action Canceled");
}
}
private class LogoutRequestListener extends BaseRequestListener {
public void onComplete(String response) {
// callback should be run in the original thread,
// not the background thread
mHandler.post(new Runnable() {
public void run() {
SessionEvents.onLogoutFinish();
}
});
}
}
}
錯誤：
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): FATAL EXCEPTION: main
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): java.lang.NullPointerException
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at com.ex.softZilla.Facebook.startSingleSignOn(Facebook.java:221)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at com.ex.softZilla.Facebook.authorize(Facebook.java:190)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at com.ex.softZilla.Facebook.authorize(Facebook.java:114)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at com.ex.softZilla.SettingActivity$1.onClick(SettingActivity.java:127)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at android.view.View.performClick(View.java:2408)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at android.view.View$PerformClick.run(View.java:8816)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at android.os.Handler.handleCallback(Handler.java:587)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at android.os.Handler.dispatchMessage(Handler.java:92)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at android.os.Looper.loop(Looper.java:123)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at android.app.ActivityThread.main(ActivityThread.java:4627)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at java.lang.reflect.Method.invokeNative(Native Method)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at java.lang.reflect.Method.invoke(Method.java:521)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-05 15:35:05.351: ERROR/AndroidRuntime(6175): at dalvik.system.NativeStart.main(Native Method)
錯誤發生在哪裏？什麼是堆棧跟蹤？請考慮修剪代碼的牆，只有相關的位。 – 2011-05-05 09:47:37
這可能是一個非常簡單的問題。您只需提供堆棧跟蹤，然後修改代碼即可。 – 2011-05-05 09:49:22
您似乎有兩個Facebook變量，mFacebook和mFb。如果你初始化一個而使用另一個仍然爲空，這可能是原因嗎？ – harism 2011-05-05 09:52:59