java - 上下文在Fragment中返回null

Question

我一直很努力地在Fragment中获取空上下文。我已经阅读了所有与我相同的问题，但没有解决任何问题。我尝试了onAttach等等，但到目前为止没有任何效果。
我在这里遇到错误：


播放器= ExoPlayerFactory.newSimpleInstance（getActivity（））;


其中getActivity（）返回null

我将片段粘贴在这里，以便任何人可以看看并建议我该怎么做

public class Fragment1 extends Fragment {
 private Frag1LayoutBinding binding;
 private PlayerView playerView;
 private SimpleExoPlayer player;
 private Button button;

 private boolean playWhenReady = true;
 private int currentWindow = 0;
 private long playbackPosition = 0;


@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    binding = Frag1LayoutBinding.inflate(inflater, container, false);
    binding.button2.setText("Live");
    button = binding.button2.findViewById(R.id.button2);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            initializePlayer();
        }
    });
    return binding.getRoot();
}

private void initializePlayer() {
    player = ExoPlayerFactory.newSimpleInstance(getActivity());
    playerView.setPlayer(player);
    Uri uri = Uri.parse("https://www.radiantmediaplayer.com/media/bbb-360p.mp4");
    MediaSource mediaSource = buildMediaSource(uri);
}

private MediaSource buildMediaSource(Uri uri) {
    DataSource.Factory dataSourceFactory =
            new DefaultDataSourceFactory(getActivity(), "exoplayer-codelab");
    return new ProgressiveMediaSource.Factory(dataSourceFactory).createMediaSource(uri);
}

@Override
public void onDestroyView() {
    super.onDestroyView();
    binding = null;
}

@Override
public void onStart() {
    super.onStart();
    if(Util.SDK_INT >= 24) {
        initializePlayer();
    }
}

@Override
public void onResume() {
    super.onResume();
    hideSystemUi();
    if((Util.SDK_INT < 24 || player == null)) {
        initializePlayer();
    }
}

@Override
public void onPause() {
    super.onPause();
    if (Util.SDK_INT < 24) {
        releasePlayer();
    }
}

@Override
public void onStop() {
    super.onStop();
    if (Util.SDK_INT >= 24) {
        releasePlayer();
    }
}

private void releasePlayer() {
    if (player != null) {
        playWhenReady = player.getPlayWhenReady();
        playbackPosition = player.getCurrentPosition();
        currentWindow = player.getCurrentWindowIndex();
        player.release();
        player = null;
    }
}

@SuppressLint("InlinedApi")
private void hideSystemUi() {
    playerView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE
            | View.SYSTEM_UI_FLAG_FULLSCREEN
            | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
            | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
            | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
}

我得到的错误是


java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'void com.google.android.exoplayer2.ui.PlayerView.setPlayer（com.google.android.exoplayer2.Player）'
在com.example.tv_1.Fragment1.initializePlayer（Fragment1.java:58）
在com.example.tv_1.Fragment1.onStart（Fragment1.java:79）

Answer 1

您忘了找到playerView，这意味着方法initializePlayer中将崩溃

playerView.setPlayer(player);