Question

在Xamarin中，我遇到使用AutoCompleteTextView的自定义适配器时遇到问题。

这是我的代码：

private void SetupAutoCompleteTextViewWithCustomAdapter()
{
    List<CustomItem> customItems = new List<CustomItem>();

    CustomItem customItem = new CustomItem();
    customItem.Heading = "TestHeading";
    customItem.SubHeading = "TestSubHeading";
    customItems.Add(customItem);

    customItem = new CustomItem();
    customItem.Heading = "TestHeading 2";
    customItem.SubHeading = "TestSubHeading 2";
    customItems.Add(customItem);

    customItem = new CustomItem();
    customItem.Heading = "TestHeading 3";
    customItem.SubHeading = "TestSubHeading 3";
    customItems.Add(customItem);

    AutoCompleteTextView AutoCompleteTextViewWithCustomAdapter = (AutoCompleteTextView) FindViewById(Resource.Id.AutoCompleteTextView);
    AutoCompleteTextViewWithCustomAdapter.Adapter = new CustomAdapter (this, customItems);

}

这是我的自定义适配器：

public class CustomAdapter : BaseAdapter<CustomItem> {
    List<CustomItem> items;
    Activity context;
    public CustomAdapter(Activity context, List<CustomItem> items)
        : base()
    {
        this.context = context;
        this.items = items;
    }
    public override long GetItemId(int position)
    {
        return position;
    }
    public override CustomItem this[int position]
    {
        get { return items[position]; }
    }
    public override int Count
    {
        get { return items.Count; }
    }
    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        var item = items[position];

        View view = convertView;
        if (view == null) // no view to re-use, create new
            view = context.LayoutInflater.Inflate(Resource.Layout.CustomView, null);
        view.FindViewById<TextView>(Resource.Id.TextViewMapHeading).Text = item.Heading;
        view.FindViewById<TextView> (Resource.Id.TextViewMapHeading).TextSize = 20;
        view.FindViewById<TextView>(Resource.Id.TextViewItem).Text = item.SubHeading;
        view.FindViewById<ImageView>(Resource.Id.Image).SetImageResource(item.ImageResourceId);

        return view;
    }
}

这是我的自定义项目类：

public class CustomItem
{
    public string Heading { get; set; }
    public string SubHeading { get; set; }
    public int ImageResourceId { get; set; }
}

这是我的CustomView布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:padding="8dp">
    <LinearLayout
        android:id="@+id/Text"
        android:orientation="vertical"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingLeft="10dip">
        <TextView
            android:id="@+id/TextViewMapHeading"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:textSize="28sp" />
        <TextView
            android:id="@+id/TextViewItem"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:autoLink="all" />
    </LinearLayout>
    <ImageView
        android:id="@+id/Image"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:padding="5dp"
        android:src="@drawable/icon"
        android:visibility="invisible"
        android:layout_alignParentRight="true" />
</RelativeLayout>

以下是我收到的错误：

java.lang.ClassCastException：simplemapdemo.CustomAdapter不能强制转换为android.widget.Filterable

我可以帮忙解决这个问题吗？

提前致谢

Answer 1

由于用于Adapter的{{1}}必须是实现AutoCompleteTextView界面，因此请修改您的Filterable，如下所示：

CustomAdapter

您可以参考public class CustomAdapter extends BaseAdapter<CustomItem> implements Filterable { ArrayFilter mFilter; ... // please override other method in BaseAdatper as your need ... @Override public Filter getFilter() { if (mFilter == null) { mFilter = new ArrayFilter(); } return mFilter; } // you can modify the custom Filter used for AutoCompleteTextView as your need private class ArrayFilter extends Filter { @Override protected FilterResults performFiltering(CharSequence prefix) { FilterResults results = new FilterResults(); if (mOriginalValues == null) { synchronized (mLock) { mOriginalValues = new ArrayList<T>(mObjects); } } if (prefix == null || prefix.length() == 0) { ArrayList<T> list; synchronized (mLock) { list = new ArrayList<T>(mOriginalValues); } results.values = list; results.count = list.size(); } else { String prefixString = prefix.toString().toLowerCase(); ArrayList<T> values; synchronized (mLock) { values = new ArrayList<T>(mOriginalValues); } final int count = values.size(); final ArrayList<T> newValues = new ArrayList<T>(); for (int i = 0; i < count; i++) { final T value = values.get(i); final String valueText = value.toString().toLowerCase(); // First match against the whole, non-splitted value if (valueText.startsWith(prefixString)) { newValues.add(value); } else { final String[] words = valueText.split(" "); final int wordCount = words.length; // Start at index 0, in case valueText starts with space(s) for (int k = 0; k < wordCount; k++) { if (words[k].startsWith(prefixString)) { newValues.add(value); break; } } } } results.values = newValues; results.count = newValues.size(); } return results; } @Override protected void publishResults(CharSequence constraint, FilterResults results) { //noinspection unchecked mObjects = (List<T>) results.values; if (results.count > 0) { notifyDataSetChanged(); } else { notifyDataSetInvalidated(); } } } }的源代码。

ClassCastException使用AutoCompleteTextView的自定义适配器

1 个答案: