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我想将Facebook登录集成到我的应用程序,但当我尝试进入活动时,我的按钮是。为什么setReadPermissions呈现NullPointerException在Facebook登录在Android工作室
我跟着这个教程:http://alvarez.tech/login-facebook-en-android/
我的活动是这样的:
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
_THIS=this;
setContentView(R.layout.connexion_layout);
if(savedInstanceState!= null) return;
FrameLayout frameLayout = (FrameLayout)findViewById(R.id.fragment_container);
connexion0 = new connexion0Fragment();
connexion1 = new connexion1Fragment();
changeFragment(0);
connexionViaFacebook();
}
public void connexionViaFacebook(){
callbackManager = CallbackManager.Factory.create();
loginButton = (LoginButton) findViewById(R.id.loginButton);
loginButton.setReadPermissions(Arrays.asList("email"));
loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
@Override
public void onSuccess(LoginResult loginResult) {
goMainScreen();
}
@Override
public void onCancel() {
Toast.makeText(getApplicationContext(), R.string.cancel_login, Toast.LENGTH_SHORT).show();
}
@Override
public void onError(FacebookException error) {
Toast.makeText(getApplicationContext(), R.string.error_login, Toast.LENGTH_SHORT).show();
}
});
}
的错误是:
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.facebook.login.widget.LoginButton.setReadPermissions(java.util.List)' on a null object reference
谢谢你,它可以帮助 –