android - 从 Activity 返回后 Listview 不更新

Question

I have the following class and for some reason, when menu item1 is selected, I launch a new Activity.当 Activity 返回时，它调用 onActivityResult() 并在该函数内我试图刷新我的 ListView。不幸的是，出于某种奇怪的原因，它没有更新列表。有谁知道如何解决这个问题？当我通过调试器运行它并在 onActivityResult() 中设置断点时，它确实在 Activity 关闭后正确地命中了函数。 “m_Adapter.notifyDataSetChange()”这一行似乎什么也没做。

public class RestaurantZoom extends Activity {
    private ArrayList<FoodItem> m_FoodItems;
    private Context m_Context;
    private FoodItemAdapter m_Adapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        m_Context = this;
        super.onCreate(savedInstanceState);
        setContentView(R.layout.foodchooser);

        TextView tvName = (TextView) findViewById(R.id.txtTitleShow);

        m_FoodItems = ((ArrayList<FoodItem>) this.getIntent()
                .getSerializableExtra("FoodItems"));
        tvName.setText(this.getIntent().getExtras().getString("RestaurantName"));

        ListView lv = (ListView) findViewById(R.id.listView1);
        m_Adapter = new FoodItemAdapter(this, R.layout.row, m_FoodItems);
        lv.setAdapter(m_Adapter);
        // lv.setBackgroundResource(R.drawable.arbys_logo_small);
        // lv.setCacheColorHint(0);

        lv.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView av, View v, int index, long arg) {
                FoodItem fi = (FoodItem) av.getAdapter().getItem(index);

                Intent i = new Intent(m_Context, ItemZoom.class);
                i.putExtra("FoodItem", fi);
                try {
                    startActivity(i);
                } catch (Exception e) {
                    Exception ex = e;
                }
            }
        });

        // SetCheckedItems(this);
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        SetCheckedItems(menu);
        return super.onPrepareOptionsMenu(menu);
    }

    private void SetCheckedItems(Menu c) {
        MenuItem itemBad = c.findItem(R.id.item2);
        MenuItem itemGood = c.findItem(R.id.item3);

        String PrefFile = getString(R.string.prefname);
        SharedPreferences settings = getSharedPreferences(PrefFile, 0);
        boolean BadChecked = settings.getBoolean("BadChecked", false);
        boolean GoodChecked = settings.getBoolean("GoodChecked", false);
        itemBad.setChecked(BadChecked);
        itemGood.setChecked(GoodChecked);

        // ListView lv = (ListView) findViewById(R.id.listView1);
        // m_Adapter = new FoodItemAdapter(this, R.layout.row,
        // m_FoodItems);
        // lv.setAdapter(m_Adapter);
        m_Adapter.notifyDataSetChanged();

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.options_menu, menu);
        return true;        
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        m_Adapter.notifyDataSetChanged();

        /*ListView lv = (ListView) findViewById(R.id.listView1);

        m_Adapter = new FoodItemAdapter(this, R.layout.row, m_FoodItems);
        lv.setAdapter(m_Adapter);
        ((BaseAdapter) lv.getAdapter()).notifyDataSetChanged();
        lv.invalidate();*/
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle item selection
        switch (item.getItemId()) {
        case R.id.item1:
            Intent i = new Intent(m_Context, Options.class);

            try {
                // startActivity(i);
                startActivityForResult(i, 1);
            } catch (Exception e) {
                Exception ex = e;
            }
            return true;
        case R.id.item2:
            if (item.isChecked())
                item.setChecked(false);
            else
                item.setChecked(true);
            String PrefFile = getString(R.string.prefname);
            SharedPreferences settings = getSharedPreferences(PrefFile, 0);
            SharedPreferences.Editor editor = settings.edit();
            editor.putBoolean("BadChecked", item.isChecked());
            editor.commit();
            m_Adapter.notifyDataSetChanged();
            return true;
        case R.id.item3:
            if (item.isChecked())
                item.setChecked(false);
            else
                item.setChecked(true);
            String PrefFile2 = getString(R.string.prefname);
            SharedPreferences settings2 = getSharedPreferences(PrefFile2, 0);
            SharedPreferences.Editor editor2 = settings2.edit();
            editor2.putBoolean("GoodChecked", item.isChecked());
            editor2.commit();
            m_Adapter.notifyDataSetChanged();
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }
}

编辑

这是我的自定义适配器的代码:

public class FoodItemAdapter extends ArrayAdapter<FoodItem> {
    private ArrayList<FoodItem> m_items;
    private Context m_Context;

    public FoodItemAdapter(Context context, int textViewResourceId,
            ArrayList<FoodItem> items) {
        super(context, textViewResourceId, items);
        this.m_items = items;
        m_Context = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View v = convertView;
        if (v == null) {
            LayoutInflater vi = (LayoutInflater) m_Context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = vi.inflate(R.layout.row, null);
        }

        FoodItem fi = m_items.get(position);
        //if (fi != null) {
            TextView tvTop = (TextView) v.findViewById(R.id.txtTextTop);
            TextView tvBottom = (TextView) v.findViewById(R.id.txtTextBottom);
            ImageView iv = (ImageView) v.findViewById(R.id.imgIcon);
            LinearLayout lv = (LinearLayout) v.findViewById(R.id.loMainLayout);
            String PrefFile = m_Context.getString(R.string.prefname);
            SharedPreferences settings = m_Context.getSharedPreferences(PrefFile, 0);

            boolean BadChecked = settings.getBoolean("BadChecked", false);
            boolean GoodChecked = settings.getBoolean("GoodChecked", false);
            int SpinnerValue1 = settings.getInt("Spinner1Value", 0);
            int SpinnerValue2 = settings.getInt("Spinner2Value", 0);
            float NutValue1 = settings.getFloat("NutValue1", 200f);
            float NutValue2 = settings.getFloat("NutValue2", 100f);
            float BaseValue = 0.0f;
            boolean BadHighlighted = false;
            boolean GoodHighlighted = false;

            if (BadChecked)
            {
                if (SpinnerValue1 == 0)
                    BaseValue = fi.GetCalories();
                if (SpinnerValue1 == 1)
                    BaseValue = fi.GetFat();
                if (SpinnerValue1 == 2)
                    BaseValue = fi.GetSatFat();
                if (SpinnerValue1 == 3)
                    BaseValue = fi.GetTransFat();
                if (SpinnerValue1 == 4)
                    BaseValue = fi.GetFat();
                if (SpinnerValue1 == 5)
                    BaseValue = fi.GetCholesterol();
                if (SpinnerValue1 == 6)
                    BaseValue = fi.GetSodium();
                if (SpinnerValue1 == 7)
                    BaseValue = fi.GetCarbs();              
                if (SpinnerValue1 == 8)
                    BaseValue = fi.GetSugar();
                if (SpinnerValue1 == 9)
                    BaseValue = fi.GetProtein();
                if (BaseValue >= NutValue1) {
                    lv.setBackgroundColor(0xff440000);
                    BadHighlighted=true;
                }
            }
            if (GoodChecked)
            {
                if (SpinnerValue2 == 0)
                    BaseValue = fi.GetCalories();
                if (SpinnerValue2 == 1)
                    BaseValue = fi.GetFat();
                if (SpinnerValue2 == 2)
                    BaseValue = fi.GetSatFat();
                if (SpinnerValue2 == 3)
                    BaseValue = fi.GetTransFat();
                if (SpinnerValue2 == 4)
                    BaseValue = fi.GetFat();
                if (SpinnerValue2 == 5)
                    BaseValue = fi.GetCholesterol();
                if (SpinnerValue2 == 6)
                    BaseValue = fi.GetSodium();
                if (SpinnerValue2 == 7)
                    BaseValue = fi.GetCarbs();              
                if (SpinnerValue2 == 8)
                    BaseValue = fi.GetSugar();
                if (SpinnerValue2 == 9)
                    BaseValue = fi.GetProtein();
                if (BaseValue <= NutValue2) {
                    lv.setBackgroundColor(0xff004400);
                    GoodHighlighted=true;
                }
                if ((BaseValue <= NutValue2) && (BadHighlighted))
                    lv.setBackgroundColor(0xff552200);
            }
            if (!BadChecked && !GoodChecked)
            {
                lv.setBackgroundColor(0xff000000);
            }
            if (GoodHighlighted == false && BadHighlighted==false)
            {
                lv.setBackgroundColor(0xff000000);
            }
            //lv.setBackgroundColor(0xffff0000);
            tvTop.setText(fi.GetFoodItem());

            String QuickView = "<b>Calories:</b> " + (new DecimalFormat("#.#")).format(fi.GetCalories());
            QuickView = QuickView + "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b>Fat:</b> " + (new DecimalFormat("#.#")).format(fi.GetFat()) + "g";
            QuickView = QuickView + "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b>Carbs:</b> " + (new DecimalFormat("#.#")).format(fi.GetCarbs()) + "g";
            tvBottom.setText(Html.fromHtml(QuickView));

            if (!fi.GetFoodIcon().equals(""))
            {
                if (fi.GetFoodIcon().equals("hamburger_icon"))
                {
                    iv.setImageResource(R.drawable.hamburger_icon);
                }
                if (fi.GetFoodIcon().equals("chicken_icon"))
                {
                    iv.setImageResource(R.drawable.chicken_icon);
                }
                if (fi.GetFoodIcon().equals("fish_icon"))
                {
                    iv.setImageResource(R.drawable.fish_icon);
                }
                if (fi.GetFoodIcon().equals("fries_icon"))
                {
                    iv.setImageResource(R.drawable.fries_icon);
                }
                if (fi.GetFoodIcon().equals("salad_icon"))
                {
                    iv.setImageResource(R.drawable.salad_icon);
                }
                if (fi.GetFoodIcon().equals("onion_rings_icon"))
                {
                    iv.setImageResource(R.drawable.onion_rings_icon);
                }
                if (fi.GetFoodIcon().equals("soft_drink_icon"))
                {
                    iv.setImageResource(R.drawable.soft_drink_icon);
                }
                if (fi.GetFoodIcon().equals("drink_icon"))
                {
                    iv.setImageResource(R.drawable.soft_drink_icon);
                }
                if (fi.GetFoodIcon().equals("milkshake_icon"))
                {
                    iv.setImageResource(R.drawable.milkshake_icon);
                }
                if (fi.GetFoodIcon().equals("cake_icon"))
                {
                    iv.setImageResource(R.drawable.cake_icon);
                }
                if (fi.GetFoodIcon().equals("breakfast_icon"))
                {
                    iv.setImageResource(R.drawable.bacon_eggs_icon);
                }
                if (fi.GetFoodIcon().equals("hotdog_icon"))
                {
                    iv.setImageResource(R.drawable.hotdog_icon);
                }
                if (fi.GetFoodIcon().equals("root_beer_float_icon"))
                {
                    iv.setImageResource(R.drawable.root_beer_float_icon);
                }
                if (fi.GetFoodIcon().equals("slush_icon"))
                {
                    iv.setImageResource(R.drawable.slush_icon);
                }
                if (fi.GetFoodIcon().equals("wing_icon"))
                {
                    iv.setImageResource(R.drawable.wing_icon);
                }
                if (fi.GetFoodIcon().equals("ice_cream_cone_icon"))
                {
                    iv.setImageResource(R.drawable.ice_cream_cone_icon);
                }
                if (fi.GetFoodIcon().equals("ice_cream_icon"))
                {
                    iv.setImageResource(R.drawable.ice_cream_cone_icon);
                }
                if (fi.GetFoodIcon().equals("smoothie_icon"))
                {
                    iv.setImageResource(R.drawable.smoothie_icon);
                }
                if (fi.GetFoodIcon().equals("sub_icon"))
                {
                    iv.setImageResource(R.drawable.sub_icon);
                }
                if (fi.GetFoodIcon().equals("sandwich_icon"))
                {
                    iv.setImageResource(R.drawable.sandwich_icon);
                }
                if (fi.GetFoodIcon().equals("soup_icon"))
                {
                    iv.setImageResource(R.drawable.soup_icon);
                }
                if (fi.GetFoodIcon().equals("potato_chips_icon"))
                {
                    iv.setImageResource(R.drawable.potato_chips_icon);
                }
                if (fi.GetFoodIcon().equals("pizza_icon"))
                {
                    iv.setImageResource(R.drawable.pizza_icon);
                }
                if (fi.GetFoodIcon().equals("taco_icon"))
                {
                    iv.setImageResource(R.drawable.taco_icon);
                }
                if (fi.GetFoodIcon().equals("burrito_icon"))
                {
                    iv.setImageResource(R.drawable.burrito_icon);
                }
                if (fi.GetFoodIcon().equals("nachos_icon"))
                {
                    iv.setImageResource(R.drawable.nachos_icon);
                }
                if (fi.GetFoodIcon().equals("noodles_icon"))
                {
                    iv.setImageResource(R.drawable.noodles_icon);
                }
                if (fi.GetFoodIcon().equals("tomato_icon"))
                {
                    iv.setImageResource(R.drawable.tomato_icon);
                }
                if (fi.GetFoodIcon().equals("beef_icon"))
                {
                    iv.setImageResource(R.drawable.beef_icon);
                }
            } else {
                iv.setVisibility(View.INVISIBLE);
            }
        //}
        return v;
    }
}

Answer 1

notifyDataSetChanged() 只是告诉适配器通知 View 重新加载其内容...

Notifies the attached View that the underlying data has been changed and it should refresh itself.

您需要在调用此之前更新适配器，否则 View 只会从适配器重新加载相同的数据。