导航抽屉的自定义适配器

Question

我有一个使用ArrayAdapter 的导航抽屉，如documentation 所示。我想为每个导航抽屉项目设置ImageView 图标，所以我需要创建一个自定义适配器来使用，但我不确定如何做到这一点。我在下面运行的内容不会导致应用程序崩溃，但导航抽屉打开时是空的，里面什么都没有。你能帮帮我吗？提前致谢！

到目前为止，我为自定义适配器所做的工作：

public class CustomAdapter extends ArrayAdapter
{
    private final Context context;

    public CustomAdapter(Context context)
    {
       super(context, R.layout.drawer_list_item);
       this.context = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View v = inflater.inflate(R.layout.drawer_list_item, parent, false);
        TextView textViewHome = (TextView) v.findViewById(R.id.drawerHomeTextView);
        ImageView imageViewHome = (ImageView) v.findViewById(R.id.drawerHomeImage);
        TextView textViewList = (TextView) v.findViewById(R.id.drawerListTextView);
        ImageView imageViewList = (ImageView) v.findViewById(R.id.drawerListImage);

        return v;
    }
}

在MainActivity中设置抽屉：

mDrawerList = (ListView) findViewById(R.id.leftDrawer);

mDrawerList.setAdapter(new CustomAdapter(this));

使用的ListView：

<ListView android:id="@+id/leftDrawer"
    android:layout_width="240dp"
    android:layout_height="match_parent"
    android:layout_gravity="left"
    android:choiceMode="singleChoice"
    android:divider="@android:color/transparent"
    android:dividerHeight="0dp"
    android:background="#111"/>

drawer_list_item.xml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content"
    android:layout_width="match_parent">

    <RelativeLayout
        android:id="@+id/drawerRelativeLayoutHome"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/drawerHomeImage"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_centerVertical="true"
            android:paddingStart="4dp"
            android:paddingEnd="4dp"
            android:paddingLeft="4dp"
            android:src="@drawable/ic_menu_home"/>

        <TextView
            android:id="@+id/drawerHomeTextView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@+id/drawerHomeImage"
            android:layout_toEndOf="@+id/drawerHomeImage"
            android:background="@drawable/background_activated"
            android:paddingLeft="4dp"
            android:paddingRight="4dp"
            android:paddingTop="12dp"
            android:paddingBottom="12dp"
            android:text="Home"
            android:textSize="20sp"/>
    </RelativeLayout>

    <RelativeLayout
        android:id="@+id/drawerRelativeLayoutList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/drawerRelativeLayoutHome">

        <!-- same as above, but ic_menu_archive as drawable, and "List" as text -->

    </RelativeLayout>

</RelativeLayout>

Answer 1

对于您的自定义适配器：

public class NavDrawerAdapter extends ArrayAdapter<NavDrawerItem>
{
    private final Context context;
    private final int layoutResourceId;
    private NavDrawerItem data[] = null;

    public NavDrawerAdapter(Context context, int layoutResourceId, NavDrawerItem [] data)
    {
        super(context, layoutResourceId, data);
        this.context = context;
        this.layoutResourceId = layoutResourceId;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        LayoutInflater inflater = ((Activity) context).getLayoutInflater();

        View v = inflater.inflate(layoutResourceId, parent, false);

        ImageView imageView = (ImageView) v.findViewById(R.id.navDrawerImageView);
        TextView textView = (TextView) v.findViewById(R.id.navDrawerTextView);

        NavDrawerItem choice = data[position];

        imageView.setImageResource(choice.icon);
        textView.setText(choice.name);

        return v;
    }
}

对于NavDrawerItem：

public class NavDrawerItem
{
    public int icon;
    public String name;

    public NavDrawerItem(int icon, String name)
    {
        this.icon = icon;
        this.name = name;
    }
}

对于drawer_list_item.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:background="?android:attr/activatedBackgroundIndicator"
    android:minHeight="?android:attr/listPreferredItemHeightSmall"
    android:padding ="10dp">

    <ImageView
        android:id="@+id/navDrawerImageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:paddingRight="10dp"/>

    <TextView
       android:id="@+id/navDrawerTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_toRightOf="@+id/navDrawerImageView"
        android:paddingRight="10dp"
        android:textAppearance="?android:attr/textAppearanceListItemSmall"/>

</RelativeLayout>

在MainActivity.java 中，实例化NavDrawerItem 对象的数组，并为每个对象使用适当的drawable 和名称，然后在设置适配器时传递此数组，如下所示：

mDrawerList.setAdapter(new YourAdapter(this, R.layout.drawer_list_item, yourArray));

Answer 2

更新
1) 我没有看到要在您的代码中显示的数据源 - 您没有在构造函数或任何其他方式中传递它
2) 在getView() 中，您应该为您的视图设置值
3) 为了提高效率，如果不是null，您必须重新使用convertView
4) 最后 - 为您的 CustomAdapter 覆盖以下方法：

    @Override
    public int getViewTypeCount() {
   ...
    }


    @Override
    public int getItemViewType(int position) {
   ...
    }

    @Override
    public int getCount() {
    ...
    }

    @Override
    public YOUR_ITEM_TYPE getItem(int position) {
    ...
    }

    @Override
    public long getItemId(int position) {
    ...
    }

    @Override
    public boolean hasStableIds() {
    ...
    }

    @Override
    public boolean isEmpty() {
    ...
    }

    @Override
    public boolean areAllItemsEnabled() {
    ...
    }

    @Override
    public boolean isEnabled(int position) {
    ...
    }