如何实现两级DrawerLayout

Question

我正在尝试实现两级DrawerLayout.作为基准,我正在使用http://developer.android.com/training/implementing-navigation/nav-drawer.html上的Google星球示例.所以我想扩展这个例子,这样从行星列表中选择一个行星,用行星上的城市列表替换行星列表(除了地球以外大多空白 - 我仍在充实我的数据: - )).

我想我可以采取三种方法: -

1. 替换ListView
2. 保留ListView,但替换其ArrayAdapter
3. 保留ListView和ArrayAdapter,但替换适配器的数据

所以尝试选项3(这是最好的方法吗？),在我的DrawerItemClickListener中,我执行以下操作...

arrayAdapter.clear(); 
arrayAdapter.addAll(arrayListOfCities);
arrayAdapter.notifyDataSetChanged(); 
mDrawerList.invalidateViews();
mDrawerList.forceLayout();
mDrawerList.refreshDrawableState();

但它似乎没有用,即行星列表不会被城市列表所取代.

我的方法是否正确？如果是,我如何让列表刷新？

Answer 1

替换ListView

真的没有必要.

保留ListView,但替换其ArrayAdapter

这将是最容易实现的.首先,将以下字符串数组(城市名称)添加到res/values/strings.xml:

<string-array name="mercury_array">
    <item>Undiscovered City 1 (Mercury)</item>
    <item>Undiscovered City 2 (Mercury)</item>
    <item>Undiscovered City 3 (Mercury)</item>
    <item>Undiscovered City 4 (Mercury)</item>
</string-array>
<string-array name="venus_array">
    <item>Undiscovered City 1 (Venus)</item>
    <item>Undiscovered City 2 (Venus)</item>
    <item>Undiscovered City 3 (Venus)</item>
    <item>Undiscovered City 4 (Venus)</item>
</string-array>
<string-array name="earth_array">
    <item>New York</item>
    <item>Hong Kong</item>
    <item>New Delhi</item>
    <item>London</item>
</string-array>
<string-array name="mars_array">
    <item>Undiscovered City 1 (Mars)</item>
    <item>Undiscovered City 2 (Mars)</item>
    <item>Undiscovered City 3 (Mars)</item>
    <item>Undiscovered City 4 (Mars)</item>
</string-array>
<string-array name="jupiter_array">
    <item>Undiscovered City 1 (Jupiter)</item>
    <item>Undiscovered City 2 (Jupiter)</item>
    <item>Undiscovered City 3 (Jupiter)</item>
    <item>Undiscovered City 4 (Jupiter)</item>
</string-array>
<string-array name="saturn_array">
    <item>Undiscovered City 1 (Saturn)</item>
    <item>Undiscovered City 2 (Saturn)</item>
    <item>Undiscovered City 3 (Saturn)</item>
    <item>Undiscovered City 4 (Saturn)</item>
</string-array>
<string-array name="uranus_array">
    <item>Undiscovered City 1 (Uranus)</item>
    <item>Undiscovered City 2 (Uranus)</item>
    <item>Undiscovered City 3 (Uranus)</item>
    <item>Undiscovered City 4 (Uranus)</item>
</string-array>
<string-array name="neptune_array">
    <item>Undiscovered City 1 (Neptune)</item>
    <item>Undiscovered City 2 (Neptune)</item>
    <item>Undiscovered City 3 (Neptune)</item>
    <item>Undiscovered City 4 (Neptune)</item>
</string-array>

创建方法loadContentList(int)在MainActivity.这是在主菜单点击项目时调用的方法:

private void loadContentList(int position) {

    setTitle(mPlanetTitles[position]);

    String[] content;

    switch(position) {
    case 0:
            content = getResources().getStringArray(R.array.mercury_array);
            break;
    case 1:
            content = getResources().getStringArray(R.array.venus_array);
            break;
    case 2:
            content = getResources().getStringArray(R.array.earth_array);
            break;
    case 3:
            content = getResources().getStringArray(R.array.mars_array);
            break;
    case 4:
            content = getResources().getStringArray(R.array.jupiter_array);
            break;
    case 5:
            content = getResources().getStringArray(R.array.saturn_array);
            break;
    case 6:
            content = getResources().getStringArray(R.array.uranus_array);
            break;
    case 7:
            content = getResources().getStringArray(R.array.neptune_array);
            break;
    default:
            content = getResources().getStringArray(R.array.neptune_array);     
}

    // Change ListView's adapter    
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, content));

    // Change OnItemClickListener // CityItemClickListener is defined below
    mDrawerList.setOnItemClickListener(new CityItemClickListener());
}

由于我们想要在点击行星项目时更新ListView,我们将更改DrawerItemClickListener的方法体并调用新添加的loadContentList(int):

/* The click listner for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        //selectItem(position);
        loadContentList(position);
    }
}

单击一个城市时,我们将需要另一个OnItemClickListener来更改片段.:

private class CityItemClickListener implements ListView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

        // This is the method that was being called on planet click 
        // in the original example. Implementation of it is up to you
        selectItem(position);
    }
}

保留ListView和ArrayAdapter,但替换适配器的数据

定义ArrayAdapter:

private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;    
---------> private ArrayAdapter<String> mAdapter;     

在MainActivity的onCreate(Bundle)中:

ArrayList<String> planetList = new ArrayList<String>();

planetList.addAll(Arrays.asList(mPlanetTitles));

mAdapter = new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, planetList);

// set up the drawer's list view with items
mDrawerList.setAdapter(mAdapter);      

我们必须传递一个ArrayList以避免UnsupportedOperationException在调用时mAdapter.clear().

更改loadContentList(int)为以下内容:

private void loadContentList2(int position) {

    setTitle(mPlanetTitles[position]);

    String[] content;

    switch(position) {

        ....
        ....
    }

    ArrayList<String> cityList = new ArrayList<String>();

    cityList.addAll(Arrays.asList(content));

    mAdapter.clear();

    mAdapter.addAll(cityList);

    // update
    mAdapter.notifyDataSetChanged();        

    // Change on item click listener
    mDrawerList.setOnItemClickListener(new CityItemClickListener());

}

CityItemClickListener和DrawerItemClickListener将保持原样.唯一的变化是:我们没有在行星列表项目上创建新的ArrayAdapter点击.

您需要找出一种方法(可能是一个按钮),以便用户从城市视图返回到行星列表.

我还建议您查看ExpandableListView.它可以更优雅地解决您的问题.