可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试):

问题:

I'm following this tutorial: Android Material Design Using Tabs

Infos:

Android API Level 21
Dependecies are added to graddle file compile 'com.android.support:appcompat-v7:23.0.1' and compile 'com.android.support:design:23.0.1' }

The method "findViewById" cannot be resolved. I tried to follow this answer Cannot resolve method 'findViewById(int)' in Fragment, but this AppCompatActivity use OnCreateBundle instead OnCreateView, then i can't get the View object...

What is wrong with this code ? I'm missing some import?

    package info.androidhive.materialtabs.activity;  import android.os.Bundle; import android.support.design.widget.TabLayout; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.Toolbar;  import java.util.ArrayList; import java.util.List;  import info.androidhive.materialtabs.R; import info.androidhive.materialtabs.fragments.OneFragment; import info.androidhive.materialtabs.fragments.ThreeFragment; import info.androidhive.materialtabs.fragments.TwoFragment;  public class MainActivity extends AppCompatActivity {      private Toolbar toolbar;     private TabLayout tabLayout;     private ViewPager viewPager;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          toolbar = (Toolbar) findViewById(R.id.toolbar);         setSupportActionBar(toolbar);          getSupportActionBar().setDisplayHomeAsUpEnabled(true);          viewPager = (ViewPager) findViewById(R.id.viewpager);         setupViewPager(viewPager);          tabLayout = (TabLayout) findViewById(R.id.tabs);         tabLayout.setupWithViewPager(viewPager);     }      private void setupViewPager(ViewPager viewPager) {         ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());         adapter.addFragment(new OneFragment(), "ONE");         adapter.addFragment(new TwoFragment(), "TWO");         adapter.addFragment(new ThreeFragment(), "THREE");         viewPager.setAdapter(adapter);     }      class ViewPagerAdapter extends FragmentPagerAdapter {         private final List<Fragment> mFragmentList = new ArrayList<>();         private final List<String> mFragmentTitleList = new ArrayList<>();          public ViewPagerAdapter(FragmentManager manager) {             super(manager);         }          @Override         public Fragment getItem(int position) {             return mFragmentList.get(position);         }          @Override         public int getCount() {             return mFragmentList.size();         }          public void addFragment(Fragment fragment, String title) {             mFragmentList.add(fragment);             mFragmentTitleList.add(title);         }          @Override         public CharSequence getPageTitle(int position) {             return mFragmentTitleList.get(position);         }     } }

This is the "Error" that Android Studio show but i got 0 erros in logevent window

回答1:

You appear to be running into the corrupt cache bug in Android Studio.

This happens to me a LOT when adding custom views with a custom namespace. If you added any custom views, this could be your issue.

To fix: File > Invalidate Caches / Restart

That should reindex everything and allow for auto-completion to work, as well, your findViewById() should work. I reviewed the code and do not see any errors.