android finalizer永远不会结束并收集旧对象，这正常吗？

Question

我的简单活动有一个包含14个项目(流派)的列表视图。当我运行应用程序时，我得到了快照，内存中正常有1个GenreSelectionActivity和14个流派。然后我转到其他活动并返回，有2个GenreSelectionActivity和28个流派。其中一半是红色的，意思是finalizerReference。然后做同样的导航，它变成了3- 42，以此类推。终结器的行为正常吗？

我尝试在销毁时调用"System.exit(0)“，旧的活动被清除了，但在转换时出现了一个恼人的黑屏。

public class GenreSelectionActivity extends Activity  {

    Activity activity;
    ListView listViewGenre;
    GenreList genreList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.genre_list);
        activity = this;

        createGenrePlayButton();

        listViewGenre = (ListView) findViewById(R.id.listGenre);

        JSONObject jsonResponseGenres = s.readInternalStoragePrivate(Constants.GENRE_FILE_NAME, getApplicationContext());
        JsonResolver jsonResolver = new JsonResolver();
        genreList = jsonResolver.getGenreListWithPhasesFromJson(jsonResponseGenres);

        final GenreCircularAdapter genreCircularAdapter = new GenreCircularAdapter(activity, R.layout.genre_row, genreList);
        listViewGenre.setAdapter(genreCircularAdapter);
        listViewGenre.setSelectionFromTop(genreCircularAdapter.MIDDLE, 0);
    }


    public void createGenrePlayButton() {

        ImageView genrePlayButton = (ImageView) findViewById(R.id.genrePlayButton);

        genrePlayButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(final View view) {
                Intent questPage = new Intent(activity, QuestionManagerActivity.class);
                questPage.putExtra("genre_name", "pop");
                Phase selectedPhaseData = new Phase();
                selectedPhaseData.setHighScore(0);
                questPage.putExtra("selected_phase_data", selectedPhaseData);
                activity.startActivity(questPage);
                activity.finish();
                //System.exit(0);
            }
        });
    }
}

这是我使用的适配器：

public class GenreCircularAdapter extends ArrayAdapter<Genre> {

    private GenreList genreList;
    private Activity activity;
    LayoutInflater inflater;

    public static final int HALF_MAX_VALUE = Constants.GENRE_CIRCULAR_LISTVIEW_SIZE / 2;
    public final int MIDDLE;

    public GenreCircularAdapter(Activity activity, int resource, GenreList genreList) {
        super(activity, resource, genreList);
        this.genreList = genreList;
        this.activity = activity;
        inflater = LayoutInflater.from(activity);
        MIDDLE = HALF_MAX_VALUE - HALF_MAX_VALUE % genreList.size();
    }

    @Override
    public int getCount() {
        return Constants.GENRE_CIRCULAR_LISTVIEW_SIZE;
    }

    @Override
    public Genre getItem(int position) {
        return genreList.get(position % genreList.size());
    }

    @Override
    public long getItemId(int position) {
        return genreList.get(position % genreList.size()).getId();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        final ViewHolder genreRowHolder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.genre_row, parent, false);

            genreRowHolder = new ViewHolder();
            genreRowHolder.attachChildViews(convertView);
            convertView.setTag(genreRowHolder);
        } else 
            genreRowHolder = (ViewHolder) convertView.getTag();

        Genre genre = getItem(position);
        genreRowHolder.genreName.setText(genre.getName());

        try {
            int genreImageResID = activity.getResources().getIdentifier(String.valueOf("genre_" + genre.getId()), "drawable", activity.getPackageName());

            genreRowHolder.genreImageView.setImageDrawable(activity.getResources().getDrawable(genreImageResID));
            genreRowHolder.genreImageView.setColorFilter(0x96064e66, PorterDuff.Mode.SRC_ATOP);
        } catch (Exception e){
            Log.e("img_not_found", "genre_" + genre.getId() + " - " + getClass().getSimpleName());
        }

        return convertView;
    }

    private static class ViewHolder {
        public TextView genreName;
        public ImageView genreImageView;
        public ImageView genreLockImageView;

        public void attachChildViews (View convertView) {
            genreName = (TextView) convertView.findViewById(R.id.genreName);
            genreImageView = (ImageView) convertView.findViewById(R.id.genreImageView);
            genreLockImageView = (ImageView) convertView.findViewById(R.id.genreLockImage);
        }
    }
}

Answer 1

我没有发现问题所在。我试过这个变通方法，现在看起来没什么问题。

@Override
protected void onDestroy() {

    // remove all content view
    ((FrameLayout)findViewById(android.R.id.content)).removeAllViews();

    // empty arraylist
    genreList.clear();
    genreList.trimToSize();

    // call garbage collector (it may not effect anything)
    Runtime.getRuntime().gc();
    System.gc();
    System.runFinalization();
}