java.lang.ClassCastException 上下文错误

Question

大家好，我是使用 Firebase Firestore 在 Android Studio 上开发完整应用程序的新手。我在 youtube 上关注带有 firestores 文档的视频，我想做的只是从我的“Anket”集合中获取所有文档，这是一个调查集合，并将它们列出在弹出屏幕上。感谢您的时间和友好的回答.MainFragmentActivity.java:public class MainFragmentActivity extends AppCompatActivity {    private static final String TAG = "MainActivity";    private SectionPageAdapter mSectionPageAdapter;    private ViewPager mViewPager;    FirebaseAuth mAuth = FirebaseAuth.getInstance();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main_fragment2);        Log.d(TAG,"onCreate:Starting");        mViewPager = findViewById(R.id.container);        setupViewPager(mViewPager);        mViewPager.setOffscreenPageLimit(4);        mSectionPageAdapter = new SectionPageAdapter(getSupportFragmentManager());        TabLayout tabLayout = findViewById(R.id.tabs);        tabLayout.setupWithViewPager(mViewPager);    }    private void setupViewPager(ViewPager viewPager){        SectionPageAdapter adapter = new SectionPageAdapter(getSupportFragmentManager());        adapter.addFragment(new ProfileFragment(), "Profile");        adapter.addFragment(new MessageFragment(), "Messages");        adapter.addFragment(new MatchFragment(), "Matches");        adapter.addFragment(new ShopFragment(), "Shop");        viewPager.setAdapter(adapter);    }    public void logoutUser(View view) {        mAuth.signOut();        Intent intent = new Intent (MainFragmentActivity.this, ChooseLoginRegistration.class);        startActivity(intent);        finish();        return;    }    public void openUpAnket (View view){        Intent intent = new Intent(MainFragmentActivity.this,Pop.class);        startActivity(intent);    }}Pop.javapublic class Pop extends Activity implements Serializable {private FirebaseFirestore surveyDb = FirebaseFirestore.getInstance();

Answer 1

AnketItemAdapter mAnketItemAdapter = new AnketItemAdapter(this ,mAnketList);

这里的this是指OnCompleteListener您创建的实例，而不是Activity（这是一个上下文）。试试Pop.this吧，这将引用外部 Activity 实例。