Could not initialize LoginButton Facebook-sdk for android

问题

im working on an android project an i want to put a Facebook Login feature, i added the Facebook sdk Correctly but i could not initialize LoginButton

**java.lang.NoClassDefFoundError: Could not initialize class       com.facebook.login.widget.LoginButton**
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:413)
at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:105)
at com.android.tools.idea.rendering.LayoutlibCallback.loadView(LayoutlibCallback.java:176)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:132)
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)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:400)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:332)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
at com.android.tools.idea.rendering.RenderService$5.compute(RenderService.java:708)
at com.android.tools.idea.rendering.RenderService$5.compute(RenderService.java:697)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:932)
at com.android.tools.idea.rendering.RenderService.createRenderSession(RenderService.java:697)
at com.android.tools.idea.rendering.RenderService.render(RenderService.java:816)
at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$6.run(AndroidDesignerEditorPanel.java:480)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:327)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at   java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

here is my AppManifest.xml :

<?xml version="1.0" encoding="utf-8"?>

<uses-permission android:name="android.permission.INTERNET"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

    <activity
        android:name=".helloActivity"
        android:label="@string/title_activity_hello" >
    </activity>

    <activity android:name="com.facebook.FacebookActivity"
        android:configChanges=
            "keyboard|keyboardHidden|screenLayout|screenSize|orientation"
        android:theme="@android:style/Theme.Translucent.NoTitleBar"
        android:label="@string/app_name" />
    <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/app_id"/>
</application>

I specified the App_id in Strings.xml. Thanks for help

回答1:

This is due to non-initialization of FacebookSdk before its usage. Just add below line:

FacebookSdk.sdkInitialize(mContext);

in case host of LoginButton is:
1.Activity- before setContentView(R.layout.activity_main)
2.Fragment- before inflater.inflate(R.layout.fragment_main, container, false)

Also don't forget to listen the callback in onActivityResult() in above cases to update the UI of LoginButton.

回答2:

I checked on latest SDK4.0.1, in that com.facebook.login.widget.LoginButton is available. But this was not found in facebook-android-sdk-3.17.1, there we have only com.facebook.widget.LoginButton available. Facebook didn't notified the developers or in their changelogs that LoginButton class moved to sub folder.

Very strange why facebook not updating correctly.. Even the doc for Android login is wrong!!

回答3:

Add this to you Manifest.xml

<meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/facebook_app_id" />
<meta-data android:name="com.facebook.sdk.ApplicationName" android:value="@string/app_name" />

来源：https://stackoverflow.com/questions/29316447/could-not-initialize-loginbutton-facebook-sdk-for-android