私のアンドロイドアプリでFacebookのログインが機能していません

Question

私は自分のアプリでFacebookのログインを実装しようとしていますが、いつでも私のアプリを起動するとクラッシュします。私はfacebook developerサイトに従っています。ここに私のコードです。

MainActivity.java

package com.algor7.samplelogin; 
... 
public class MainActivity extends Activity { 

private LoginButton loginButton; 
private CallbackManager callbackManager; 
private AccessTokenTracker accessTokenTracker; 
private AccessToken accessToken; 
private ProfileTracker profileTracker; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    FacebookSdk.sdkInitialize(this.getApplicationContext()); 
    callbackManager = CallbackManager.Factory.create(); 

    accessTokenTracker = new AccessTokenTracker() { 
     @Override 
     protected void onCurrentAccessTokenChanged(
       AccessToken oldAccessToken, 
       AccessToken currentAccessToken) { 
      // Set the access token using 
      // currentAccessToken when it's loaded or set. 
     } 
    }; 
    // If the access token is available already assign it. 
    accessToken = AccessToken.getCurrentAccessToken(); 

    profileTracker = new ProfileTracker() { 
     @Override 
     protected void onCurrentProfileChanged(
       Profile oldProfile, 
       Profile currentProfile) { 
      // App code 
     } 
    }; 

    loginButton.findViewById(R.id.login_button); 
    loginButton.setReadPermissions("email"); 
    loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() { 
     @Override 
     public void onSuccess(LoginResult loginResult) { 
      // App code 
     } 

     @Override 
     public void onCancel() { 
      // App code 
     } 

     @Override 
     public void onError(FacebookException exception) { 
      // App code 
     } 
    }); 

} 

@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    super.onActivityResult(requestCode, resultCode, data); 
    callbackManager.onActivityResult(requestCode, resultCode, data); 
} 

@Override 
public void onDestroy() { 
    super.onDestroy(); 
    accessTokenTracker.stopTracking(); 
    profileTracker.stopTracking(); 
} 

} 

activity_main.xml

<RelativeLayout 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:gravity="center" 
tools:context=".MainActivity"> 

<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" /> 

</RelativeLayout> 

のstrings.xml

<resources> 
<string name="app_name">SampleLogin</string> 
<string name="facebook_app_id">4932151xxxxxxxx</string> 
<string name="fb_login_protocol_scheme">fb4932151xxxxxxxx</string> 

AndroidManifest.xmlを

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.algor7.samplelogin" > 

<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" > 

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

    <activity 
     android:name=".MainActivity" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 

    <activity 
     android:name="com.facebook.CustomTabActivity" 
     android:exported="true"> 
     <intent-filter> 
      <action android:name="android.intent.action.VIEW" /> 
      <category android:name="android.intent.category.DEFAULT" /> 
      <category android:name="android.intent.category.BROWSABLE" /> 
      <data android:scheme="@string/fb_login_protocol_scheme" /> 
     </intent-filter> 
    </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" /> 

</application> 

build.gradle（プロジェクト:)

buildscript { 
repositories { 
    mavenCentral() 
} 
dependencies { 
    classpath 'com.android.tools.build:gradle:1.3.0' 

    // NOTE: Do not place your application dependencies here; they belong 
    // in the individual module build.gradle files 
} 
} 

allprojects { 
    repositories { 
    jcenter() 
    } 
} 

build.gradle（モジュール：アプリ）

apply plugin: 'com.android.application' 

android { 
compileSdkVersion 23 
buildToolsVersion "23.0.3" 

defaultConfig { 
    applicationId "com.algor7.samplelogin" 
    minSdkVersion 17 
    targetSdkVersion 23 
    versionCode 1 
    versionName "1.0" 
} 
buildTypes { 
    release { 
     minifyEnabled false 
     proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' 
    } 
} 
} 

dependencies { 
compile fileTree(dir: 'libs', include: ['*.jar']) 
compile 'com.android.support:appcompat-v7:24.0.0-alpha2' 
compile 'com.facebook.android:facebook-android-sdk:[4,5)' 
} 

Logcat：

--------- beginning of crash 
05-16 15:28:57.915 2478-2478/? E/AndroidRuntime﹕ FATAL EXCEPTION: main 
Process: com.algor7.samplelogin, PID: 2478 
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.algor7.samplelogin/com.algor7.samplelogin.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View com.facebook.login.widget.LoginButton.findViewById(int)' on a null object reference 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) 
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
     at android.app.ActivityThread.-wrap11(ActivityThread.java) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:148) 
     at android.app.ActivityThread.main(ActivityThread.java:5417) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View com.facebook.login.widget.LoginButton.findViewById(int)' on a null object reference 
     at com.algor7.samplelogin.MainActivity.onCreate(MainActivity.java:54) 
     at android.app.Activity.performCreate(Activity.java:6251) 
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
     at android.app.ActivityThread.-wrap11(ActivityThread.java) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:148) 
     at android.app.ActivityThread.main(ActivityThread.java:5417) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

HELしてくださいこの問題を解決するために私に教えてください。前もって感謝します！代わりに

loginButton.findViewById(R.id.login_button); 

使用

findViewById(R.id.login_button); 

の

Answer 1

問題はloginButtonがnullであることを意味は何

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View com.facebook.login.widget.LoginButton.findViewById(int)' on a null object reference 
    at com.algor7.samplelogin.MainActivity.onCreate(MainActivity.java:54) 

です。 loginButton内のビューlogin_buttonがまだ初期化されていないことを確認しようとしています。代わりにアクティビティ内のビューを見つける必要があります。

Answer 2

Try to do like this: 





public class MainActivity extends Activity { 
    private CallbackManager mfbCallbackManager; 
    private LoginManager mfbLoginManager; 
    Override 
     protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 

      FacebookSdk.sdkInitialize(getApplicationContext()); 
      setContentView(R.layout. activity_main); 
    mfbCallbackManager = CallbackManager.Factory.create(); 
      mfbLoginManager = LoginManager.getInstance(); 
      mfbLoginManager.registerCallback(mfbCallbackManager, new FacebookCallback<LoginResult>() { 

       @Override 
       public void onSuccess(LoginResult fbLoginResult) { 

        GraphRequest fbGraphRequest = GraphRequest.newMeRequest(fbLoginResult.getAccessToken(), new GraphRequest.GraphJSONObjectCallback() { 

         @Override 
         public void onCompleted(JSONObject object, GraphResponse response) { 
          Profile fbProfile = Profile.getCurrentProfile(); 
          String email = null, gender = null, dob = null; 
          try { 
           email = object.getString("email"); 
           gender = object.getString("gender"); 
           dob = object.getString("birthday"); 
          } catch (JSONException e) { 
           AppUtil.writeLog(TAG, e.getMessage()); 
          } 
          mCustomer = new Customer(); 
          try { 
           mCustomer.setCustFbId(fbProfile.getId()); 
           mCustomer.setCustName(fbProfile.getName()); 
           mCustomer.setCustFbiImageUrl(fbProfile.getProfilePictureUri(Constants.FB_PROFILE_PIC_WIDTH, Constants.FB_PROFILE_PIC_HEIGHT).toString()); 
           mCustomer.setCustEmail(email); 
           mCustomer.setCustGender(gender); 
           mCustomer.setCustType(Constants.CUSTOMER_ROLE); 
           mCustomer.setCustDob(dob); 
          } catch (NullPointerException e) { 
           AppUtil.writeLog(TAG, e.getMessage()); 
          } 

          loginWithFb(); 
         } 
        }); 

        Bundle parameters = new Bundle(); 
        parameters.putString("fields", "gender, age_range, email, birthday"); 
        fbGraphRequest.setParameters(parameters); 
        fbGraphRequest.executeAsync(); 

    } 

    private void loginWithFb() { 
      EndpointInterface apiService = AppUtil.getRetrofitInstance().create(EndpointInterface.class); 
      Call<LoginResp> call = apiService.loinWithFacebook(
        mCustomer.getCustFbId(), 
        mCustomer.getCustName(), 
        mCustomer.getCustType(), 
        mCustomer.getCustFbiImageUrl(), 
        mCustomer.getCustEmail(), 
        mCustomer.getCustDob(), 
        mCustomer.getCustGender(), 
        mAppPreferences.getString(Constants.SETTINGS_GCM_ID, ""), 
        IS_PUSH_ENABLED 
      ); 

final ProgressDialog dialog; 
     dialog = new ProgressDialog(LoginActivity.this); 
     dialog.setMessage(getString(R.string.fb_login_wait_msg)); 
     dialog.setCanceledOnTouchOutside(false); 
     dialog.show(); 

     call.enqueue(new Callback<LoginResp>() { 
      @Override 
      public void onResponse(Call<LoginResp> call, Response<LoginResp> response) { 
       mCustomer.setCustId(response.body().getCustId()); 
       mCustomer.setIsNew(response.body().getIsNew()); 

       SharedPreferences.Editor preferenceEditor = mAppPreferences.edit(); 
       preferenceEditor.putString(Constants.SETTINGS_OBJ_CUSTOMER, new Gson().toJson(mCustomer)); 
       preferenceEditor.putBoolean(Constants.SETTINGS_IS_LOGGED_IN, true); 
       preferenceEditor.apply(); 

       dialog.dismiss(); 
       startActivity(new Intent(LoginActivity.this, HomeActivity.class)); 
       finish(); 
      } 

      @Override 
      public void onFailure(Call<LoginResp> call, Throwable t) { 
       dialog.dismiss(); 
       Toast.makeText(LoginActivity.this, R.string.server_error + t.getMessage(), Toast.LENGTH_LONG).show(); 
      } 
     }); 
    } 

Answer 3

アクティビティではなくフラグメントでログインする必要があります。私が間違っていないならば、facebook docはあなたにフラグメントにログインボタンを置くように頼みます。 Then set up the button in your UI by adding it to a fragment and update your activity to use your fragment.