Question

你好我的ListView有一个非常奇怪的故障：当我滚动时，列表的残像保持静止，就像视图出现两次一样，通常具有透明背景滚动而另一个保持静止静态，你看到另一个后面。这是它的外观：

我尝试做的是按照本教程实现字母列表视图：http://www.brightec.co.uk/ideas/android-listview-alphabet-scroller 它工作正常，然后我想提取代码并将其放在一个片段中，但它以相反的顺序显示，所以我按照这篇文章：Horizontal LinearLayout displaying components in reverse order并用RelativeLayout替换原始的LinearLayout，并且它在启动时表现得很奇怪。这是片段的xml代码：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/contacts_root"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <LinearLayout
        android:id="@+id/sideIndex"
        android:layout_width="40dip"
        android:layout_alignParentRight="true"
        android:layout_height="fill_parent"
        android:gravity="center_horizontal"
        android:orientation="vertical" >
    </LinearLayout>

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_marginRight="40dip"
        android:layout_alignParentLeft="true"
        android:layout_height="match_parent"
        android:fastScrollEnabled="true"
        android:cacheColorHint="@android:color/transparent"/>
</RelativeLayout>

这是我的活动代码：

public class MainActivity extends GlActivity {
    IconTextMenu menu;

    private GestureDetector mGestureDetector;

    public void setmGestureDetector(GestureDetector mGestureDetector) {
        this.mGestureDetector = mGestureDetector;
    }

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

        Log.d("DEBUG", "MainActivity.onCreate()");
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.main_fragment, new ContactsFragment());
        fragmentTransaction.commit();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (mGestureDetector.onTouchEvent(event)) {
            return true;
        } else {
            return false;
        }
    }

    @Override
    protected @Nullable @LayoutRes Integer getLayoutResource() {
        return R.layout.activity_main;
    }

    @Override
    protected void initializeData() {
        super.initializeData();

        menu = new IconTextMenu();
        menu.add(new IconTextMenuEntry(R.drawable.icon_import_export, R.string.import_export));
        menu.add(new IconTextMenuEntry(R.drawable.icon_tag, R.string.manage_tags));
        menu.add(new IconTextMenuEntry(R.drawable.icon_settings, R.string.settings));
    }

    @Override
    protected void initializeComponents() {
        super.initializeComponents();

        UiBuilder builder = new UiBuilder(this);
        builder.buildDrawerMenu(R.id.main_menu, menu);
        builder.buildToolbar(R.id.main_toolbar, R.id.main_drawer);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                ((DrawerLayout) findViewById(R.id.main_drawer)).openDrawer(GravityCompat.START);
                return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

我的片段代码：

public class ContactsFragment extends Fragment {
    MainActivity context;
    ListView listView;
    private AlphabetListAdapter adapter = new AlphabetListAdapter();
    private List<Object[]> alphabet = new ArrayList<Object[]>();
    private HashMap<String, Integer> sections = new HashMap<String, Integer>();
    private int sideIndexHeight;
    private static float sideIndexX;
    private static float sideIndexY;
    private int indexListSize;

    private class SideIndexGestureListener extends GestureDetector.SimpleOnGestureListener {
        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            // we know already coordinates of first touch
            // we know as well a scroll distance
            sideIndexX = sideIndexX - distanceX;
            sideIndexY = sideIndexY - distanceY;

            // when the user scrolls within our side index
            // we can show for every position in it a proper
            // item in the country list
            if (sideIndexX >= 0 && sideIndexY >= 0) {
                displayListItem();
            }

            return super.onScroll(e1, e2, distanceX, distanceY);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        this.context = (MainActivity) context;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        Log.d("DEBUG", "ContactsFragment.onCreateView()");
        View rootView = inflater.inflate(R.layout.activity_main_fragment_contacts, container, false);
        return rootView;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        context.setmGestureDetector(new GestureDetector(context, new SideIndexGestureListener()));
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        listView = (ListView) view.findViewById(android.R.id.list);

        List<String> countries = populateCountries();
        Collections.sort(countries);

        List rows = new ArrayList();
        int start = 0;
        int end = 0;
        String previousLetter = null;
        Object[] tmpIndexItem = null;
        Pattern numberPattern = Pattern.compile("[0-9]");

        for (String country : countries) {
            String firstLetter = country.substring(0, 1);

            // Group numbers together in the scroller
            if (numberPattern.matcher(firstLetter).matches()) {
                firstLetter = "#";
            }

            // If we've changed to a new letter, add the previous letter to the alphabet scroller
            if (previousLetter != null && !firstLetter.equals(previousLetter)) {
                end = rows.size() - 1;
                tmpIndexItem = new Object[3];
                tmpIndexItem[0] = previousLetter.toUpperCase(Locale.UK);
                tmpIndexItem[1] = start;
                tmpIndexItem[2] = end;
                alphabet.add(tmpIndexItem);

                start = end + 1;
            }

            // Check if we need to add a header row
            if (!firstLetter.equals(previousLetter)) {
                rows.add(new AlphabetListAdapter.Section(firstLetter));
                sections.put(firstLetter, start);
            }

            // Add the country to the list
            rows.add(new AlphabetListAdapter.Item(country));
            previousLetter = firstLetter;
        }

        if (previousLetter != null) {
            // Save the last letter
            tmpIndexItem = new Object[3];
            tmpIndexItem[0] = previousLetter.toUpperCase(Locale.UK);
            tmpIndexItem[1] = start;
            tmpIndexItem[2] = rows.size() - 1;
            alphabet.add(tmpIndexItem);
        }

        adapter.setRows(rows);
        listView.setAdapter(adapter);

        updateList();
    }

    private List<String> populateCountries() {
        List<String> countries = new ArrayList<>();
        countries.add("Afghanistan");
        countries.add("Albania");
        countries.add("Bahrain");
        countries.add("Bangladesh");
        countries.add("Cambodia");
        countries.add("Cameroon");
        countries.add("Denmark");
        countries.add("Djibouti");
        countries.add("East Timor");
        countries.add("Ecuador");
        countries.add("Fiji");
        countries.add("Finland");
        countries.add("Gabon");
        countries.add("Georgia");
        countries.add("Haiti");
        countries.add("Holy See");
        countries.add("Iceland");
        countries.add("India");
        countries.add("Jamaica");
        countries.add("Japan");
        countries.add("Pakistan");
        countries.add("Palau");
        countries.add("Qatar");
        countries.add("Romania");
        countries.add("Russia");
        countries.add("Saint Kitts and Nevis");
        countries.add("Saint Lucia");
        countries.add("Taiwan");
        countries.add("Tajikistan");
        countries.add("Uganda");
        countries.add("Ukraine");
        countries.add("Vanuatu");
        countries.add("Venezuela");
        countries.add("Yemen");
        countries.add("Zambia");
        countries.add("Zimbabwe");
        countries.add("0");
        countries.add("2");
        countries.add("9");
        return countries;
    }

    public void displayListItem() {
        LinearLayout sideIndex = (LinearLayout) getView().findViewById(R.id.sideIndex);
        sideIndexHeight = sideIndex.getHeight();
        // compute number of pixels for every side index item
        double pixelPerIndexItem = (double) sideIndexHeight / indexListSize;

        // compute the item index for given event position belongs to
        int itemPosition = (int) (sideIndexY / pixelPerIndexItem);

        // get the item (we can do it since we know item index)
        if (itemPosition < alphabet.size()) {
            Object[] indexItem = alphabet.get(itemPosition);
            int subitemPosition = sections.get(indexItem[0]);

            listView.setSelection(subitemPosition);
        }
    }

    public void updateList() {
        LinearLayout sideIndex = (LinearLayout) getView().findViewById(R.id.sideIndex);
        sideIndex.removeAllViews();
        indexListSize = alphabet.size();
        if (indexListSize < 1) {
            return;
        }

        int indexMaxSize = (int) Math.floor(sideIndex.getHeight() / 20);
        int tmpIndexListSize = indexListSize;
        while (tmpIndexListSize > indexMaxSize) {
            tmpIndexListSize = tmpIndexListSize / 2;
        }
        double delta;
        if (tmpIndexListSize > 0) {
            delta = indexListSize / tmpIndexListSize;
        } else {
            delta = 1;
        }

        TextView tmpTV;
        for (double i = 1; i <= indexListSize; i = i + delta) {
            Object[] tmpIndexItem = alphabet.get((int) i - 1);
            String tmpLetter = tmpIndexItem[0].toString();

            tmpTV = new TextView(context);
            tmpTV.setText(tmpLetter);
            tmpTV.setGravity(Gravity.CENTER);
            tmpTV.setTextSize(15);
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT, 1);
            tmpTV.setLayoutParams(params);
            sideIndex.addView(tmpTV);
        }

        sideIndexHeight = sideIndex.getHeight();

        sideIndex.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                // now you know coordinates of touch
                sideIndexX = event.getX();
                sideIndexY = event.getY();

                // and can display a proper item it country list
                displayListItem();

                return false;
            }
        });
    }
}

Android ListView滚动故障

0 个答案: