我尝试用facebook SDK测试登录.

所以我添加编译’com.facebook.@L_403_0@:facebook-android-sdk:4.0.0′.

然后添加FacebookSdk.sdkInitialize(getApplicationContext());
到MainActivity.java

但是当我补充

@H_301_9@<com.facebook.login.widget.LoginButton android:id="@+id/login_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:layout_marginTop="30dp" android:layout_marginBottom="30dp" />`

我有以下错误：

@H_301_9@Rendering Problems The following classes could not be instantiated: com.facebook.login.widget.LoginButton (Open Class,Show Exception) Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE Exception Details java.lang.NoClassDefFoundError: Could not initialize class com.facebook.login.widget.LoginButton at java.lang.reflect.Constructor.newInstance(Constructor.java:422) at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:806) at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64) at android.view.LayoutInflater.rInflate(LayoutInflater.java:782) at android.view.LayoutInflater.inflate(LayoutInflater.java:504) at android.view.LayoutInflater.inflate(LayoutInflater.java:385) Copy stack to clipboard