Solve some Sonarlint warnings

app/src/main/java/org/schabi/newpipe/local/dialog/PlaylistDialog.java

@@ -9,15 +9,20 @@ import android.view.Window;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.DialogFragment;
+import androidx.fragment.app.FragmentManager;
 
 import org.schabi.newpipe.NewPipeDatabase;
 import org.schabi.newpipe.database.stream.model.StreamEntity;
 import org.schabi.newpipe.local.playlist.LocalPlaylistManager;
+import org.schabi.newpipe.player.Player;
 import org.schabi.newpipe.util.StateSaver;
 
 import java.util.List;
+import java.util.Objects;
 import java.util.Queue;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
 import io.reactivex.rxjava3.disposables.Disposable;
@@ -131,13 +136,13 @@ public abstract class PlaylistDialog extends DialogFragment implements StateSave
      * @param context        context used for accessing the database
      * @param streamEntities used for crating the dialog
      * @param onExec         execution that should occur after a dialog got created, e.g. showing it
-     * @return Disposable
+     * @return the disposable that was created
      */
     public static Disposable createCorrespondingDialog(
             final Context context,
             final List<StreamEntity> streamEntities,
-            final Consumer<PlaylistDialog> onExec
-    ) {
+            final Consumer<PlaylistDialog> onExec) {
+
         return new LocalPlaylistManager(NewPipeDatabase.getInstance(context))
                 .hasPlaylists()
                 .observeOn(AndroidSchedulers.mainThread())
@@ -147,4 +152,30 @@ public abstract class PlaylistDialog extends DialogFragment implements StateSave
                                 : PlaylistCreationDialog.newInstance(streamEntities))
                 );
     }
+
+    /**
+     * Creates a {@link PlaylistAppendDialog} when playlists exists,
+     * otherwise a {@link PlaylistCreationDialog}. If the player's play queue is null or empty, no
+     * dialog will be created.
+     *
+     * @param player          the player from which to extract the context and the play queue
+     * @param fragmentManager the fragment manager to use to show the dialog
+     * @return the disposable that was created
+     */
+    public static Disposable showForPlayQueue(
+            final Player player,
+            @NonNull final FragmentManager fragmentManager) {
+
+        final List<StreamEntity> streamEntities = Stream.of(player.getPlayQueue())
+                .filter(Objects::nonNull)
+                .flatMap(playQueue -> Objects.requireNonNull(playQueue).getStreams().stream())
+                .map(StreamEntity::new)
+                .collect(Collectors.toList());
+        if (streamEntities.isEmpty()) {
+            return Disposable.empty();
+        }
+
+        return PlaylistDialog.createCorrespondingDialog(player.getContext(), streamEntities,
+                dialog -> dialog.show(fragmentManager, "PlaylistDialog"));
+    }
 }