活动中的午餐片段时崩溃

Question

I'm building media player and i want to lunch fragment to control actions like play/pause when user play audio file but it didn't work and throw this exception:

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mediaplayer, PID: 1092
java.lang.IllegalStateException: Activity has been destroyed
    at androidx.fragment.app.FragmentManagerImpl.enqueueAction(FragmentManagerImpl.java:1566)
    at androidx.fragment.app.BackStackRecord.commitInternal(BackStackRecord.java:317)
    at androidx.fragment.app.BackStackRecord.commit(BackStackRecord.java:282)
    at com.example.mediaplayer.MainActivity.doActionToFile(MainActivity.java:126)
    at com.example.mediaplayer.RecyclerViewAdapter$FileLayoutHolder.onClick(RecyclerViewAdapter.java:68)

this is code i use to lunch the fragment from static method in mainActivity (this method is called when use click on audio item):

AudioPlayerFragment player = AudioPlayerFragment.newInstance();
           FragmentActivity fragmentActivity = new FragmentActivity();
           FragmentManager manager = fragmentActivity.getSupportFragmentManager();
           FragmentTransaction transaction = manager.beginTransaction();
           transaction.add(R.id.fragment_container,player);
           transaction.addToBackStack(null);
           transaction.commit();

and this is AudioPlayerFragment class:

public class AudioPlayerFragment extends Fragment {
    public AudioPlayerFragment(){}

    public static AudioPlayerFragment newInstance(){return new AudioPlayerFragment();}

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.audio_control_layout, container, false);
        return view;
    }
}

this is main activity layout witch i use Framelayout to be fragment's container:

    <?xml version="1.0" encoding="utf-8"?>

<androidx.viewpager.widget.ViewPager 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/pager"
    android:layout_height="match_parent"
    android:layout_width="match_parent">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <FrameLayout
        android:id="@+id/fragment_container"
        android:name="SimpleFragment"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout="@layout/audio_control_layout">
    </FrameLayout>

</androidx.viewpager.widget.ViewPager>

and this is audio_control_layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <ToggleButton
        android:id="@+id/tb_love"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_margin="@dimen/space16"
        android:textOff=""
        android:textOn=""
        android:button="@drawable/toggle_button"
        android:background="@null"/>
    <LinearLayout
        android:id="@+id/ll_bottom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_alignParentBottom="true"
        android:padding="@dimen/space16"
        android:weightSum="5">
        <ImageButton
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:src="@drawable/ic_repeat"
            android:background="@null"/>
        <ImageButton
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:src="@drawable/ic_backward"
            android:background="@null"/>
        <ImageButton
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:src="@drawable/ic_play"
            android:background="@null"/>

        <ImageButton
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:src="@drawable/ic_forward"
            android:background="@null"/>

        <ImageButton
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:src="@drawable/ic_shuffle"
            android:background="@null"/>
    </LinearLayout>
    <RelativeLayout
        android:id="@+id/rl_progress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/ll_bottom"
        android:layout_margin="@dimen/space16">
        <TextView
            android:id="@+id/tv_current_time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true"
            android:text="2:01"
            android:textSize="14sp"
            android:textColor="@color/colorTextGrey"/>
        <TextView
            android:id="@+id/tv_full_time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:text="3:47"
            android:textSize="14sp"
            android:textColor="@color/colorTextGrey" />
        <ProgressBar
            android:layout_width="match_parent"
            android:layout_height="@dimen/space8"
            android:layout_toLeftOf="@id/tv_full_time"
            android:layout_toRightOf="@id/tv_current_time"
            android:layout_marginLeft="@dimen/space16"
            android:layout_marginRight="@dimen/space16"
            android:layout_centerVertical="true"
            android:progressBackgroundTint="#E9E9E9"
            android:progress="50"
            android:indeterminate="false"
            style="@style/Widget.AppCompat.ProgressBar.Horizontal"
            android:progressDrawable="@drawable/progress_bar"/>
    </RelativeLayout>
    <TextView
        android:id="@+id/tv_artist"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@id/rl_progress"
        android:layout_centerHorizontal="true"
        android:text="by From First to Last "
        android:textSize="14sp"
        android:textColor="@color/colorTextGrey" />
    <TextView
        android:id="@+id/tv_song"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@id/tv_artist"
        android:layout_marginBottom="@dimen/space8"
        android:layout_centerHorizontal="true"
        android:text="Make War"
        android:textSize="18sp"
        android:textColor="@color/colorTextDark" />
  <!--  <androidx.viewpager.widget.ViewPager
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/pager_audio"
        android:layout_height="match_parent"
        android:layout_width="match_parent" >-->

    <ImageView
        android:layout_above="@id/tv_song"
        android:layout_below="@id/tb_love"
        android:layout_marginTop="@dimen/space16"
        android:layout_marginBottom="@dimen/space16"
        android:src="@drawable/album2"
        android:id="@+id/iv_cover"
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:layout_gravity="center"/>
    <!--</androidx.viewpager.widget.ViewPager>-->

</RelativeLayout>

it is right to use fragment or use another activity? what do normal music player use to control over this actions activity or fragment?

Answer 1

You can call this.getSupportFragmentManager(); in the doActionToFile method since the frameLayout is already a part of your mainActivity no need to instantiate a new activity. You need to use the contextualized manager this is probably the main cause of the crash.

If you want to create a new activity you need to use the normal lifecycle methods, I would suggest using first Intent and creating a custom Activity class that does the Fragment transaction in the onCreate or onResume method of the activity. Activity appears destroyed because it does not exist. Also maybe you can try using a DialogFragment so you don't require creating a whole activity.