找不到 Android Facebook LoginButton 类

Question

我将 Facebook SDK (v3.21.1) 模块导入到 Android Studio (v1.0.2) 中，并尝试按照建议使用 com.facebook.widget.LoginButton 创建一个 LoginActivity in the documentation使用以下代码:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.facebook.widget.LoginButton
        android:id="@+id/authButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="30dp"
        />

</LinearLayout>

但是，Android Studio 中的渲染器说找不到 LoginButton 类:

找不到以下类:- com.facebook.widget.LoginButton

我确实知道该类存在，因为我可以打开该文件，并且它位于正确的位置:

我知道它存在，但为了向 Android Studio 证明它确实存在，我尝试按照渲染器中的建议创建一个类，但收到以下错误:

我也尝试过以下方法:

• 重新导入 Facebook SDK(删除/重新导入 Facebook 模块:删除物理文件等)
• 重新打开我的项目
• 重新打开 Android Studio
• 构建项目

没有任何作用。可笑的是连自动补全都能看到类:

编辑:我尝试在模拟器中运行应用程序，忽略渲染错误，应用程序崩溃并出现以下错误:

12-31 03:47:15.593    2824-2824/com.test.playground E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.test.playground, PID: 2824
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test.playground/com.test.playground.LoginActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class com.facebook.widget.LoginButton
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            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:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class com.facebook.widget.LoginButton
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:707)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
            at android.app.Activity.setContentView(Activity.java:1929)
            at com.test.playground.LoginActivity.onCreate(LoginActivity.java:15)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            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:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.ClassNotFoundException: Didn't find class "com.facebook.widget.LoginButton" on path: DexPathList[[zip file "/data/app/com.test.playground-2.apk"],nativeLibraryDirectories=[/data/app-lib/com.test.playground-2, /system/lib]]
            at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
            at android.view.LayoutInflater.createView(LayoutInflater.java:559)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:696)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
            at android.app.Activity.setContentView(Activity.java:1929)
            at com.test.playground.LoginActivity.onCreate(LoginActivity.java:15)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            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:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)

同样，类确实存在，只是 Android Studio 似乎找不到它。该类在 com.faceook.widget.LoginButton 下的项目目录中可见...我不知道我错过了什么。几个小时以来，我一直在努力解决这个问题，但没有任何效果。

Answer 1

对于那些仍然有问题的人，将 com.facebook.widget.LoginButton 更改为 com.facebook.login.widget.LoginButton 可能会有所帮助。