在选项卡布局中看不到我的 cardView
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【中文标题】在选项卡布局中看不到我的 cardView【英文标题】：can't see my cardView in tab layout 【发布时间】：2018-06-11 12:08:38 【问题描述】：我想在 Tablayout 的选项卡之一中显示 cardView 列表，但是当应用程序运行时选项卡显示为空白。我没有在互联网上得到解决方案。 cardView 列表应显示的选项卡之一中有四个选项卡，但模拟器显示空白活动。我没有在选项卡中获取任何类型的内容。
这是我的主要活动：
public class MainActivity extends AppCompatActivity
private ViewPagerAdapter pagerAdapter;
private ViewPager mViewPager;
private Toolbar toolbar;
private TabLayout tabLayout;
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
pagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(pagerAdapter);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener()
@Override
public void onTabSelected(TabLayout.Tab tab)
mViewPager.setCurrentItem(tab.getPosition());//setting current selected item over viewpager
switch (tab.getPosition())
case 0:
Log.e("TAG", "TAB1");
break;
case 1:
Log.e("TAG", "TAB2");
break;
case 2:
Log.e("TAG", "TAB3");
break;
@Override
public void onTabUnselected(TabLayout.Tab tab)
@Override
public void onTabReselected(TabLayout.Tab tab)
);
@Override
public boolean onCreateOptionsMenu(Menu menu)
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
@Override
public boolean onOptionsItemSelected(MenuItem item)
int id = item.getItemId();
if (id == R.id.action_settings)
return true;
return super.onOptionsItemSelected(item);
public static class PlaceholderFragment extends Fragment
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment()
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 = inflater.inflate(R.layout.fragment_main, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.recyclerView);
textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
*/
this is the fragment
public class SongsTab extends Fragment
RecyclerView recyclerView;
private ArrayList<songInfo> songs= new ArrayList<>();
songAdapter songAdapter;
MediaPlayer mediaPlayer;
SeekBar seekBar;
SeekBar seekBar2;
private int seekForwardTime = 5000;
private int seekBackwardTime = 5000;
Cursor cursor;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View v= inflater.inflate(R.layout.songs, container, false);
recyclerView =(RecyclerView)v.findViewById(R.id.recyclerView);
seekBar =(SeekBar)v.findViewById(R.id.seekBar);
songAdapter = new songAdapter(songs, getContext());
recyclerView.setAdapter(songAdapter);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
linearLayoutManager.getOrientation());
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.addItemDecoration(dividerItemDecoration);
mediaPlayer = new MediaPlayer();
songAdapter.setOnitemClickListener(new songAdapter.OnitemClickListener()
@Override
public void onItemclick(final songAdapter.ViewHolder holder, View v, songInfo obj, int position)
System.gc();
int songPath = cursor.getColumnIndex(MediaStore.Audio.Media.DATA);
cursor.moveToPosition(position);
final String filename = cursor.getString(songPath);
if (mediaPlayer.isPlaying())
// mediaPlayer.stop();
mediaPlayer.reset();
// mediaPlayer.release();
//mediaPlayer = null;
else try
/* Intent intent = new Intent( MainActivity.this, Main2Activity.class );
startActivity(intent);*/
try
mediaPlayer.setDataSource(filename);
catch (IOException e1)
e1.printStackTrace();
mediaPlayer.prepareAsync();
mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener()
@Override
public void onPrepared (MediaPlayer mp)
mp.start();
seekBar.setProgress(0);
seekBar.setMax(mediaPlayer.getDuration());
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener()
@Override
public void onProgressChanged(SeekBar seekBar, int i, boolean b)
mediaPlayer.seekTo(i);
@Override
public void onStartTrackingTouch(SeekBar seekBar)
@Override
public void onStopTrackingTouch(SeekBar seekBar)
);
// );
// mediaPlayer.prepareAsync();
);
catch(Exception e)
;
);
checkUserPermission();
return v;
private void checkUserPermission()
if(Build.VERSION.SDK_INT>=23)
if(ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.READ_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED)
requestPermissions(new String[]Manifest.permission.READ_EXTERNAL_STORAGE,123);
return;
loadSongs();
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults)
switch (requestCode)
case 123:
if (grantResults[0] == PackageManager.PERMISSION_GRANTED)
loadSongs();
else
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
Toast.makeText(getContext(), "Permission Denied", Toast.LENGTH_SHORT).show();
checkUserPermission();
break;
default:
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
private void loadSongs()
Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
String selection = MediaStore.Audio.Media.IS_MUSIC+"!=0";
cursor = getActivity().getContentResolver().query(uri,null,selection,null,null);
if(cursor != null)
if(cursor.moveToFirst())
do
String name = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE));
String artist = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST));
int songPath = cursor.getColumnIndex(MediaStore.Audio.Media.DATA);
songInfo s = new songInfo(name,artist,songPath);
songs.add(s);
while (cursor.moveToNext());
// cursor.close();
songAdapter = new songAdapter(songs, getActivity());
@Override
public void onDestroy()
// TODO Auto-generated method stub
super.onDestroy();
cursor.close();
/*
public void nextSong()
int currentPosition = mediaPlayer.getCurrentPosition();
// check if seekForward time is lesser than song duration
if(currentPosition + seekForwardTime <= mediaPlayer.getDuration())
// forward song
mediaPlayer.seekTo(currentPosition + seekForwardTime);
else
// forward to end position
mediaPlayer.seekTo(mediaPlayer.getDuration());
*/
public void play()
mediaPlayer.start();
this is xml mainactivity
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_content"
android:layout_
android:layout_
android:fitsSystemWindows="true"
tools:context="com.example.murarilal.musicmania.MainActivity">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_
android:layout_
android:paddingTop="@dimen/appbar_padding_top"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_
android:layout_
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/AppTheme.PopupOverlay">
</android.support.v7.widget.Toolbar>
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
android:layout_
android:layout_ />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/container"
android:layout_
android:layout_
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>
recycler view.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_
android:layout_>
<android.support.v7.widget.RecyclerView
android:layout_
android:layout_
android:id="@+id/recyclerView">
</android.support.v7.widget.RecyclerView>
<SeekBar
android:layout_
android:layout_
android:id="@+id/seekBar"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:layout_marginBottom="60dp"
android:layout_alignParentEnd="true" />
</RelativeLayout>
我几乎尝试了所有的解决方案，但我并没有摆脱这个问题。
【问题讨论】：
从 MainActivity 类调用片段。 ***.com/questions/37653037/… 【参考方案1】：我看不到您将片段放入 TabLayout 的部分。当 onTabSelected 事件触发时，您应该将 Fragment 放在选项卡中。如果没有，则选项卡只是空的。
【讨论】：
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