我正在尝试使用 facebook 的“Hackbook”应用程序作为对我的编码的参考，这是一个片段而不是活动......但是我在第 64 行遇到错误，即：
mText = (TextView) getView().findViewById(R.id.txt);
日志猫：
05-20 17:47:34.741: W/dalvikvm(1766): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
05-20 17:47:34.761: E/AndroidRuntime(1766): FATAL EXCEPTION: main
05-20 17:47:34.761: E/AndroidRuntime(1766): java.lang.NullPointerException
05-20 17:47:34.761: E/AndroidRuntime(1766): at com.projectcaruso.naturalfamilyplaning.LoginFragment.init(LoginFragment.java:78)
05-20 17:47:34.761: E/AndroidRuntime(1766): at com.projectcaruso.naturalfamilyplaning.LoginFragment.onCreateView(LoginFragment.java:61)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1460)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:429)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.os.Handler.handleCallback(Handler.java:725)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.os.Handler.dispatchMessage(Handler.java:92)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.os.Looper.loop(Looper.java:137)
05-20 17:47:34.761: E/AndroidRuntime(1766): at android.app.ActivityThread.main(ActivityThread.java:5041)
05-20 17:47:34.761: E/AndroidRuntime(1766): at java.lang.reflect.Method.invokeNative(Native Method)
05-20 17:47:34.761: E/AndroidRuntime(1766): at java.lang.reflect.Method.invoke(Method.java:511)
05-20 17:47:34.761: E/AndroidRuntime(1766): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-20 17:47:34.761: E/AndroidRuntime(1766): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-20 17:47:34.761: E/AndroidRuntime(1766): at dalvik.system.NativeStart.main(Native Method)
片段：包com.projectcaruso.naturalfamilyplaning；
import org.json.JSONException;
import org.json.JSONObject;
import com.projectcaruso.naturalfamilyplaning.R;
import com.projectcaruso.naturalfamilyplaning.SessionEvents.AuthListener;
import com.projectcaruso.naturalfamilyplaning.SessionEvents.LogoutListener;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.facebook.android.AsyncFacebookRunner;
import com.facebook.android.Facebook;
import com.facebook.android.Util;
@SuppressWarnings("deprecation")
public class LoginFragment extends Fragment implements OnClickListener{
/*
* Your Facebook Application ID must be set before running this example See
* http://www.facebook.com/developers/createapp.php
*/
public static String APP_ID;
private LoginButton mLoginButton;
private TextView mText;
private ImageView mUserPic;
private Handler mHandler;
ProgressDialog dialog;
final static int AUTHORIZE_ACTIVITY_RESULT_CODE = 0;
final static int PICK_EXISTING_PHOTO_RESULT_CODE = 1;
String[] permissions = { "offline_access", "publish_stream", "user_photos", "publish_checkins",
"photo_upload" };
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (APP_ID == null) {
Util.showAlert(getActivity(), "Warning", "Facebook Applicaton ID must be "
+ "specified before running this example: see FbAPIs.java");
return;
}
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_login, null);
init();
mHandler = new Handler();
/*
* Source Tag: login_tag
*/
mLoginButton.init(getActivity(), AUTHORIZE_ACTIVITY_RESULT_CODE, Utility.mFacebook, permissions);
if (Utility.mFacebook.isSessionValid()) {
requestUserData();
}
return view;
}
private void init() {
mText = (TextView) getView().findViewById(R.id.txt);
mUserPic = (ImageView) getView().findViewById(R.id.user_pic);
APP_ID = getResources().getString(R.string.app_id);
// Create the Facebook Object using the app id.
Utility.mFacebook = new Facebook(APP_ID);
// Instantiate the asynrunner object for asynchronous api calls.
Utility.mAsyncRunner = new AsyncFacebookRunner(Utility.mFacebook);
mLoginButton = (LoginButton) getView().findViewById(R.id.login);
// restore session if one exists
SessionStore.restore(Utility.mFacebook, getActivity());
SessionEvents.addAuthListener(new FbAPIsAuthListener());
SessionEvents.addLogoutListener(new FbAPIsLogoutListener());
}
/*
* Request user name, and picture to show on the main screen.
*/
public void requestUserData() {
mText.setText("Fetching user name, profile pic...");
Bundle params = new Bundle();
params.putString("fields", "name, picture");
Utility.mAsyncRunner.request("me", params, new UserRequestListener());
}
/*
* Callback for fetching current user's name, picture, uid.
*/
public class UserRequestListener extends BaseRequestListener {
@Override
public void onComplete(final String response, final Object state) {
JSONObject jsonObject;
try {
jsonObject = new JSONObject(response);
final String picURL = jsonObject.getJSONObject("picture")
.getJSONObject("data").getString("url");
final String name = jsonObject.getString("name");
Utility.userUID = jsonObject.getString("id");
mHandler.post(new Runnable() {
@Override
public void run() {
mText.setText("Welcome " + name + "!");
mUserPic.setImageBitmap(Utility.getBitmap(picURL));
}
});
} catch (JSONException e) {
e.printStackTrace();
}
}
}
public class FbAPIsAuthListener implements AuthListener {
@Override
public void onAuthSucceed() {
requestUserData();
}
@Override
public void onAuthFail(String error) {
mText.setText("Login Failed: " + error);
}
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
/*
* The Callback for notifying the application when log out starts and
* finishes.
*/
public class FbAPIsLogoutListener implements LogoutListener {
@Override
public void onLogoutBegin() {
mText.setText("Logging out...");
}
@Override
public void onLogoutFinish() {
mText.setText("You have logged out! ");
mUserPic.setImageBitmap(null);
}
}
}
XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<!-- Facebook login -->
<ImageView
android:id="@+id/user_pic"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_marginRight="6dip" />
<TextView
android:id="@+id/txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/user_pic" />
<com.projectcaruso.naturalfamilyplaning.LoginButton
android:id="@+id/login"
android:src="@drawable/login_button"
android:layout_toRightOf="@id/user_pic"
android:layout_below="@id/txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</RelativeLayout>