java.lang.NullPointerException：参数'applicationId'不能为空 - 使用 PARSE facebook 登录

Question

我正在尝试使用解析facebook登录功能，并从参考本教程解析facebook集成开始。我正在使用一个LoginActivity，它将调用ParseFacebookUtils.logIn（permissions，LoginActivity.this，new LogInCallback（），但我得到了以下异常

02-07 14:22:16.485  29990-29990/prototype.quest.cashquest E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: prototype.quest.cashquest, PID: 29990
java.lang.NullPointerException: Argument 'applicationId' cannot be null
        at com.facebook.internal.Validate.notNull(Validate.java:29)
        at com.facebook.Session.<init>(Session.java:281)
        at com.facebook.Session.<init>(Session.java:270)
        at com.facebook.Session$Builder.build(Session.java:1822)
        at com.parse.FacebookAuthenticationProvider.authenticate(FacebookAuthenticationProvider.java:116)
        at com.parse.ParseUser.authenticateAsync(ParseUser.java:1500)
        at com.parse.ParseUser.logInWithAsync(ParseUser.java:1520)
        at com.parse.ParseUser.logInWithAsync(ParseUser.java:1309)
        at com.parse.ParseFacebookUtils.logInInBackground(ParseFacebookUtils.java:478)
        at com.parse.ParseFacebookUtils.logIn(ParseFacebookUtils.java:545)
        at prototype.quest.cashquest.LoginActivity.onLoginClick(LoginActivity.java:143)
        at prototype.quest.cashquest.LoginActivity$1.onClick(LoginActivity.java:117)
        at android.view.View.performClick(View.java:4654)
        at android.view.View$PerformClick.run(View.java:19438)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:146)
        at android.app.ActivityThread.main(ActivityThread.java:5487)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
        at dalvik.system.NativeStart.main(Native Method)

这是我的登录活动：

public class LoginActivity extends Activity {
private Dialog progressDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Button login = (Button) findViewById(R.id.fb);
    login.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            onLoginClick(v);
            // Starts an intent for the sign up activity
        }
    });
    // Check if there is a currently logged in user
    // and it's linked to a Facebook account.
    ParseUser currentUser = ParseUser.getCurrentUser();
    if ((currentUser != null) && ParseFacebookUtils.isLinked(currentUser)) {
        // Go to the user info activity
        showUserDetailsActivity();
    }
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    ParseFacebookUtils.finishAuthentication(requestCode, resultCode, data);
}
public void onLoginClick(View v) {
    progressDialog = ProgressDialog.show(LoginActivity.this, "", "Logging in...", true);
    List<String> permissions = Arrays.asList("public_profile");
    ParseFacebookUtils.logIn(permissions, LoginActivity.this, new LogInCallback() {
        @Override
        public void done(ParseUser user, ParseException err) {
            progressDialog.dismiss();
            if (user == null) {
                Log.d("Facebook_login", "Uh oh. The user cancelled the Facebook login.");
            } else if (user.isNew()) {
                Log.d("Facebook_login", "User signed up and logged in through Facebook!");
                showUserDetailsActivity();
            } else {
                Log.d("Facebook_login", "User logged in through Facebook!");
                showUserDetailsActivity();
            }
        }
    });
}
private void showUserDetailsActivity() {
    Intent intent = new Intent(LoginActivity.this, MainActivity.class);
    startActivity(intent);
  }
}

以下是登录活动使用的main.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="100dp"
    android:gravity="center"
    android:text="@string/login"
    android:textSize="18sp" />
<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="100dp"
    android:id="@+id/fb"
    android:text="@string/com_facebook_loginview_log_in_button"
    android:textColor="@color/com_facebook_loginview_text_color"
    android:textSize="@dimen/com_facebook_loginview_text_size"
    android:textStyle="bold"
    android:background="@drawable/com_facebook_button_blue"
    android:drawableLeft="@drawable/com_facebook_inverse_icon"
    android:drawablePadding="@dimen/com_facebook_likebutton_compound_drawable_padding"
    android:paddingLeft="@dimen/com_facebook_loginview_padding_left"
    android:paddingTop="@dimen/com_facebook_loginview_padding_top"
    android:paddingRight="@dimen/com_facebook_loginview_padding_right"
    android:paddingBottom="@dimen/com_facebook_loginview_padding_bottom"
    android:onClick="onLoginClick"/>
 </LinearLayout>

这是一件显而易见的事情：

            <activity android:name="com.facebook.LoginActivity"
        android:label="@string/app_name" />
    <meta-data android:name="com.facebook.sdk.ApplicationId"
        android:value="my_facebook_id"/>

我不知道例外的原因，如果有人能告诉我这个可能出了什么问题，那将是非常有帮助的

我试着通过引用关于application_id不能为null的帖子进行在线研究，但情况对他们来说非常不同，所以我想发布一个新的问题，谢谢

Answer 1

我得到了答案，，这有点奇怪，但只需将"my_app_id"放在string.xml中并通过manifest.xml中的该字符串引用它就解决了问题，，，