我的构建成功完成，但应用崩溃。有人会像我的代码中那样编写有关如何使用Viewpager和Fragments将Firebase Auth与Android Studio中的Facebook Login链接的教程吗？我的应用程序中需要一个滑块。
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activitenter code herey_main);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
enter code here
mViewPager.setAdapter(mSectionsPagerAdapter);
mAuth = FirebaseAuth.getInstance();
// Initialize Facebook Login button
mCallbackManager = CallbackManager.Factory.create();
LoginButton loginButton = findViewById(R.id.login_button);
//Here problem start
loginButton.setReadPermissions("email", "public_profile");
loginButton.registerCallback(mCallbackManager, new
FacebookCallback<LoginResult>() {
@Override
enter code here
public void onSuccess(LoginResult loginResult) {
Log.d(TAG, "facebook:onSuccess:" + loginResult);
handleFacebookAccessToken(loginResult.getAccessToken());
}
@Override
public void onCancel() {
Log.d(TAG, "facebook:onCancel");
// ...
}
@Override
public void onError(FacebookException error) {
Log.d(TAG, "facebook:onError", error);
// ...
}
});
// ...
}
@Override
public void onStart() {
super.onStart();
// Check if user is signed in (non-null) and update UI accordingly.
FirebaseUser currentUser = mAuth.getCurrentUser();
if(currentUser != null){
updateUI();
}
}
private void updateUI() {
Toast.makeText(MainActivity.this, "You are logged in!" ,
Toast.LENGTH_LONG).show();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// Pass the activity result back to the Facebook SDK
mCallbackManager.onActivityResult(requestCode, resultCode, data);
}
private void handleFacebookAccessToken(AccessToken token) {
Log.d(TAG, "handleFacebookAccessToken:" + token);
AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken());
mAuth.signInWithCredential(credential)
.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
// Sign in success, update UI with the signed-in user's information
Log.d(TAG, "signInWithCredential:success");
FirebaseUser user = mAuth.getCurrentUser();
updateUI();
} else {
// If sign in fails, display a message to the user.
Log.w(TAG, "signInWithCredential:failure", task.getException());
Toast.makeText(MainActivity.this, "Authentication failed."[enter image description here][1],
Toast.LENGTH_SHORT).show();
}
// ...
}
});
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = null;
switch (getArguments().getInt(ARG_SECTION_NUMBER)) {
case 1:
rootView = inflater.inflate(R.layout.fragment_main, container, false);
break;
case 2:
rootView = inflater.inflate(R.layout.fragment_second, container, false);
break;
}
return rootView;
}
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
@Override
public int getCount() {
// Show 2 total pages.
return 2;`enter code here`
}
}
没有片段的应用程序完美运行。有人知道为什么吗？
这是例外：
2019-01-19 11：13：05.129 8439-8439 / jimmy.jimmyfindgymbuddyptl.com.myapplication E / AndroidRuntime：FATAL EXCEPTION：main流程：jimmy.jimmyfindgymbuddyptl.com.myapplication，PID：8439java.lang.RuntimeException：无法启动活动ComponentInfo {jimmy.jimmyfindgymbuddyptl.com.myapplication / jimmy.jimmyfindgymbuddyptl.com.myapplication.MainActivity}：java.lang.NullPointerException：尝试调用虚拟方法'void com.facebook.login。对空对象引用的widget.LoginButton.setReadPermissions（java.lang.String []）'在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2646）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2707）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1460）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:154）在android.app.ActivityThread.main（ActivityThread.java:6077）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:866）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:756）原因：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'void com.facebook.login.widget.LoginButton.setReadPermissions（java.lang.String []）'在jimmy.jimmyfindgymbuddyptl.com.myapplication.MainActivity.onCreate（MainActivity.java:92）在android.app.Activity.performCreate（Activity.java:6662）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1118）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2599）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2707）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1460）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:154）在android.app.ActivityThread.main（ActivityThread.java:6077）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:866）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:756）。
此按钮位于xml中：
<com.facebook.login.widget.LoginButton android:id="@+id/login_button"
android:layout_width="190dp" android:layout_height="wrap_content"
android:layout_above="@+id/textView7" android:layout_alignParentStart="true"
android:layout_marginStart="95dp" android:layout_marginBottom="6dp" />
[您似乎正在对Firebase Auth使用较旧的方法。使用Firebase Auth SDK已有最新更新，新方法非常简单且代码最少。请参阅此处以获取更多详细信息https://firebase.google.com/docs/auth/android/firebaseui
这是设置Facebook身份验证提供程序和启动身份验证意图的方法。您需要为Callaback处理和UI自定义添加单独的逻辑（如果适用），上述逻辑也可以在上述docs链接上获得。请检查一次，希望这将减少您的代码并解决此问题。
// Choose authentication providers
List<AuthUI.IdpConfig> providers = Arrays.asList(
new AuthUI.IdpConfig.FacebookBuilder().build());
// Create and launch sign-in intent
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setAvailableProviders(providers)
.build(),
RC_SIGN_IN);
我在完全相同的位置有一个类似的错误。不知道这是否对您有帮助，但是我忘记将我的内容视图设置为resources / layout文件夹中的facebook活动。
即
在onCreate方法中...
setContentView(R.layout.activity_facebook);
我希望这会有所帮助。
您可以使用Firebase Facebook身份验证。请查看https://firebase.google.com/docs/auth/android/facebook-login中的文档