java - 尽管设置了必要的属性，列表项也不会保持选中状态

Question

我试图让 ListView 中的所选项目在选择时保持突出显示，但由于某种原因，当所选项目不在 View 中时，它不会这样做。例如。当我选择项目 4 时，该列表项确实会突出显示，但当我滚动列表时，它不会保持突出显示状态，然后其他项目会随机突出显示。即使当我返回到第 4 项时，该项目也不再突出显示。我真的不明白为什么会发生这种情况。可以采取什么措施来解决这个问题？所有相关帮助将不胜感激。

fragment_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/fragmentmain">

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerVertical="false"
        android:layout_centerHorizontal="true"
        android:choiceMode="singleChoice"/>
</LinearLayout>

MainListAdapter.java

public class MainListAdapter extends BaseAdapter implements Filterable {

    private List<Main> mData;
    private List<Main> mFilteredData;
    private LayoutInflater mInflater;
    private ItemFilter mFilter;

    public MainListAdapter (List<Main> data, Context context) {
        mData = data;
        mFilteredData = new ArrayList(mData);
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return mFilteredData.size();
    }

    @Override
    public Main getItem(int position) {
        return mFilteredData.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

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

        ViewHolder holder;
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_item, parent, false);
            holder = new ViewHolder();

            holder.title = (TextView) convertView.findViewById(R.id.item);
            holder.description = (TextView) convertView.findViewById(R.id.item_description);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        Main main = getItem(position);
        holder.title.setText(main.getContinent());
        holder.description.setText(main.getDescription());
        if (main.isSelected()) {
            convertView.setBackgroundColor(Color.parseColor("#1C3F96"));
            holder.title.setTextColor(Color.parseColor("#FFFFFF"));
            holder.description.setTextColor(Color.parseColor("#FFFFFF"));
        } else {
            convertView.setBackgroundColor(Color.TRANSPARENT);
            holder.title.setTextColor(Color.parseColor("#FFFFFF"));
            holder.description.setTextColor(Color.parseColor("#B5B5B5"));
        }

        holder.title.setText(mFilteredData.get(position).getContinent());
        holder.description.setText(mFilteredData.get(position).getDescription());

        return convertView;
    }

    @Override
    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ItemFilter();
        }
        return mFilter;
    }

    /**
     * View holder
     */
    static class ViewHolder {
        private TextView title;
        private TextView description;
    }

    /**
     * Filter for filtering list items
     */
    /**
     * <p>An array filter constrains the content of the array adapter with
     * a prefix. Each item that does not start with the supplied prefix
     * is removed from the list.</p>
     */
    private class ItemFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();

            if (TextUtils.isEmpty(constraint)) {
                results.count = mData.size();
                results.values = new ArrayList(mData);
            } else {
                //Create a new list to filter on
                List<Main> resultList = new ArrayList<Main>();
                for (Main str : mData) {
                    if (str.getContinent().toLowerCase().contains(constraint.toString().toLowerCase())) {
                        resultList.add(str);
                    }
                }
                results.count = resultList.size();
                results.values = resultList;
            }
            return results;
        }

        /**
         * Runs on ui thread
         * @param constraint the constraint used for the result
         * @param results the results to display
         */
        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            if (results.count == 0) {
                mFilteredData.clear();
                notifyDataSetInvalidated();
            } else {
                mFilteredData = (ArrayList<Main>)results.values;
                notifyDataSetChanged();
            }
        }
    }
}

Main.java(在“数据”包中)

public class Main {
    public Main(){}

    private String continent;
    private String description;
    private boolean selected;

    public String getContinent(){
        return continent;
    }

    public void setContinent(String continent){
        this.continent = continent;
    }

    public String getDescription(){
        return description;
    }

    public void setDescription(String description){
        this.description = description;
    }

    private int _id;
    public void getID(int _id){
        this._id = _id;
    }

    public int setID(){
        return _id;
    }

    public boolean isSelected() {
        return selected;
    }

    public void setSelected(boolean selected) {
        this.selected = selected;
    }
}

MainActivity.java

public class MainActivity extends ActionBarActivity {

    private boolean mTwoPane;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        FragmentMain newFragment = new FragmentMain();
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.master_container, newFragment);
        transaction.commit();

        if (findViewById(R.id.detail_container) != null) {
            mTwoPane = true;

        }
    }

    @Override
    protected void onNewIntent(Intent intent) {
        handleIntent(intent);
    }

    private void handleIntent(Intent intent) {

        if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
            String query = intent.getStringExtra(SearchManager.QUERY);
            //use the query to search your data somehow
        }
    }
}

FragmentMain.java

public class FragmentMain extends ListFragment implements SearchView.OnQueryTextListener {
    private MainListAdapter mAdapter;

    public FragmentMain() {
        // Required empty constructor
    }

    /**
     * Whether or not the activity is in two-pane mode, i.e. running on a tablet
     * device.
     */
    public boolean mTwoPane;

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

        //Tell the system to call onCreateOptionsMenu
        setHasOptionsMenu(true);
        initialize(view);
        return view;
    }

    List<Main> list = new ArrayList<>();
    private void initialize(View view) {
        String[] items = getActivity().getResources().getStringArray(R.array.items);
        String[] itemDescriptions = getActivity().getResources().getStringArray(R.array.item_descriptions);
        for (int n = 0; n < items.length; n++){
            Main world = new Main();
            world.setID();
            world.setContinent(items[n]);
            world.setDescription(itemDescriptions[n]);
            list.add(world);
        }

        mAdapter = new MainListAdapter(list, getActivity());
        setListAdapter(mAdapter);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        View v = getView();

        mTwoPane = getActivity().findViewById(R.id.detail_container) != null;


        ListView lv = (ListView)v.findViewById(android.R.id.list);
        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // get the adapter, then get the name from the adapter at that position
                MainListAdapter adapter = (MainListAdapter) parent.getAdapter();
                Main main = adapter.getItem(position);

                if (mTwoPane) {
                    setItemNormal();
                    View rowView = view;
                    setItemSelected(rowView);


                Fragment newFragment;
                switch (position) {
                    case 0:
                        newFragment = new Fragment0();
                        break;
                    case 1:
                        newFragment = new Fragment1();
                        break;
                    case 2:
                        newFragment = new Fragment2();
                        break;
                    case 3:
                        newFragment = new Fragment3();
                        break;
                    case 4:
                        newFragment = new Fragment4();
                        break;
                    case 5:
                        newFragment = new Fragment5();
                        break;
                    case 6:
                        newFragment = new Fragment6();
                        break;
                    case 7:
                        newFragment = new Fragment7();
                        break;
                    case 8:
                        newFragment = new Fragment8();
                        break;
                    case 9:
                        newFragment = new Fragment9();
                        break;
                    case 10:
                        newFragment = new Fragment10();
                        break;
                    case 11:
                        newFragment = new Fragment11();
                        break;
                    case 12:
                        newFragment = new Fragment12();
                        break;
                    case 13:
                        newFragment = new Fragment13();
                        break;
                    case 14:
                        newFragment = new Fragment14();
                        break;
                    case 15:
                        newFragment = new Fragment15();
                        break;
                    case 16:
                        newFragment = new Fragment16();
                        break;
                    case 17:
                        newFragment = new Fragment17();
                        break;
                    case 18:
                        newFragment = new Fragment18();
                        break;
                    case 19:
                        newFragment = new Fragment19();
                        break;
                    case 20:
                        newFragment = new Fragment20();
                        break;
                    default:
                        newFragment = new Fragment0();
                }
                MainActivity activity = (MainActivity) view.getContext();
                FragmentTransaction transaction = activity.getSupportFragmentManager().beginTransaction();
                transaction.setCustomAnimations(R.anim.fade_out, R.anim.fade_in);
                transaction.replace(R.id.detail_container, newFragment);
                transaction.commit();
                } else {
                    Intent intent;
                    if (main.equals(view.getResources().getString(R.string.item0))) {
                        intent = new Intent(getActivity(), Activity0.class);
                    } else if (main.equals(view.getResources().getString(R.string.item1))) {
                        intent = new Intent(getActivity(), Activity1.class);
                    } else if (main.equals(view.getResources().getString(R.string.item2))) {
                        intent = new Intent(getActivity(), Activity2.class);
                    } else if (main.equals(view.getResources().getString(R.string.item3))) {
                        intent = new Intent(getActivity(), Activity3.class);
                    } else if (main.equals(view.getResources().getString(R.string.item4))) {
                        intent = new Intent(getActivity(), Activity4.class);
                    } else if (main.equals(view.getResources().getString(R.string.item5))) {
                        intent = new Intent(getActivity(), Activity5.class);
                    } else if (main.equals(view.getResources().getString(R.string.item6))) {
                        intent = new Intent(getActivity(), Activity6.class);
                    } else if (main.equals(view.getResources().getString(R.string.item7))) {
                        intent = new Intent(getActivity(), Activity7.class);
                    } else if (main.equals(view.getResources().getString(R.string.item8))) {
                        intent = new Intent(getActivity(), Activity8.class);
                    } else if (main.equals(view.getResources().getString(R.string.item9))) {
                        intent = new Intent(getActivity(), Activity9.class);
                    } else if (main.equals(view.getResources().getString(R.string.item10))) {
                        intent = new Intent(getActivity(), Activity10.class);
                    } else if (main.equals(view.getResources().getString(R.string.item11))) {
                        intent = new Intent(getActivity(), Activity11.class);
                    } else if (main.equals(view.getResources().getString(R.string.item12))) {
                        intent = new Intent(getActivity(), Activity12.class);
                    } else if (main.equals(view.getResources().getString(R.string.item13))) {
                        intent = new Intent(getActivity(), Activity13.class);
                    } else if (main.equals(view.getResources().getString(R.string.item14))) {
                        intent = new Intent(getActivity(), Activity14.class);
                    } else if (main.equals(view.getResources().getString(R.string.item15))) {
                        intent = new Intent(getActivity(), Activity15.class);
                    } else if (main.equals(view.getResources().getString(R.string.item16))) {
                        intent = new Intent(getActivity(), Activity16.class);
                    } else if (main.equals(view.getResources().getString(R.string.item17))) {
                        intent = new Intent(getActivity(), Activity17.class);
                    } else if (main.equals(view.getResources().getString(R.string.item18))) {
                        intent = new Intent(getActivity(), Activity18.class);
                    } else if (main.equals(view.getResources().getString(R.string.item19))) {
                        intent = new Intent(getActivity(), Activity19.class);
                    } else if (main.equals(view.getResources().getString(R.string.item20))) {
                        intent = new Intent(getActivity(), Activity20.class);
                    } else {
                        intent = new Intent(getActivity(), Activity0.class);
                    }
                    startActivity(intent);
                }
            }

            public void setItemSelected(View view) {
                View rowView = view;
                view.setBackgroundColor(Color.parseColor("#1C3F96"));

                TextView tv0 = (TextView) rowView.findViewById(R.id.item);
                tv0.setTextColor(Color.parseColor("#FFFFFF"));

                TextView tv1 = (TextView) rowView.findViewById(R.id.item_description);
                tv1.setTextColor(Color.parseColor("#FFFFFF"));
            }

            public void setItemNormal() {
                for (int i = 0; i < getListView().getChildCount(); i++) {
                    View v = getListView().getChildAt(i);
                    v.setBackgroundColor(Color.TRANSPARENT);

                    TextView tv0 = ((TextView) v.findViewById(R.id.item));
                    tv0.setTextColor(Color.WHITE);

                    TextView tv1 = ((TextView) v.findViewById(R.id.item_description));
                    tv1.setTextColor(Color.parseColor("#B5B5B5"));
                }
            }
        });

        super.onActivityCreated(savedInstanceState);
    }

    @Override
    public void onPrepareOptionsMenu(Menu menu) {
        MenuItem searchViewMenuItem = menu.findItem(R.id.action_search);
        SearchView mSearchView = (SearchView) MenuItemCompat.getActionView(searchViewMenuItem);

        int searchImgId0 = android.support.v7.appcompat.R.id.search_button;
        ImageView v0 = (ImageView) mSearchView.findViewById(searchImgId0);
        v0.setImageResource(R.drawable.ic_action_search_light);

        int searchImgId1 = android.support.v7.appcompat.R.id.search_close_btn;
        ImageView v1 = (ImageView) mSearchView.findViewById(searchImgId1);
        v1.setImageResource(R.drawable.ic_action_content_clear_light);

        super.onPrepareOptionsMenu(menu);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        // Set up search view
        inflater.inflate(R.menu.menu_main, menu);
        MenuItem item = menu.findItem(R.id.action_search);
        SearchView searchView = (SearchView) MenuItemCompat.getActionView(item);
        searchView.setIconifiedByDefault(true);
        searchView.clearAnimation();
        searchView.setOnQueryTextListener(this);
    }

    @Override
    public boolean onQueryTextSubmit(String newText) {
        return false;
    }

    @Override
    public boolean onQueryTextChange(String newText) {
        mAdapter.getFilter().filter(newText);
        return false;
    }
}

list_item.xml

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:minHeight="?android:attr/listPreferredItemHeight"
    android:gravity="center_vertical"
    android:baselineAligned="false"
    android:paddingStart="12dp"
    android:paddingEnd="12dp"
    xmlns:android="http://schemas.android.com/apk/res/android">

        <TextView android:id="@+id/item"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:ellipsize="marquee"
            android:fadingEdge="horizontal"
            android:textColor="?android:attr/textColorPrimary" />

        <TextView android:id="@+id/item_description"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/item"
            android:layout_alignStart="@id/item"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:textColor="?android:attr/textColorSecondary" />
</RelativeLayout>

更新屏幕截图 2015 年 7 月 31 日

Answer 1

Android ListView 在滚动时重用其 View 。您需要在项目对象中存储有关所选项目的信息，并检查在 getView 中是否选择了该项目。

如果选择了setItemSelected，则调用setItemNormal，否则调用setItemNormal。这样，您将在滚动列表时更新每个项目的选定状态。

编辑

@Override
public Main getItem(int position) {
    return mFilteredData.get(position);
}

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

    ViewHolder holder;
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.list_item, parent, false);
        holder = new ViewHolder();

        holder.title = (TextView) convertView.findViewById(R.id.item);
        holder.description = (TextView) convertView.findViewById(R.id.item_description);

        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    Main main = getItem(position);
    holder.title.setText(main.getContinent());
    holder.description.setText(main.getDescription());
    if (main.isSelected()) {
        convertView.setBackgroundColor(Color.parseColor("#1C3F96"));
        holder.title.setTextColor(Color.parseColor("#FFFFFF"));
        holder.description.setTextColor(Color.parseColor("#FFFFFF"));
    } else {
        convertView.setBackgroundColor(Color.TRANSPARENT);
        holder.title.setTextColor(Color.parseColor("#FFFFFF"));
        holder.description.setTextColor(Color.parseColor("#B5B5B5"));
    }

    return convertView;
}

在您的onItemClick内:

...
switch (position) {
    case 0:
        newFragment = new Fragment0();
        break;
    case 1:
        newFragment = new Fragment1();
        break;
    // etc..
    default:
        newFragment = new Fragment0();
}