Android 中使用 ArrayAdapter 进行自定义过滤

使用 ArrayAdapter 进行自定义过滤是 Android 开发中常见的需求之一。ArrayAdapter 是 Android 提供的一个适配器类，用于将数据源与界面进行绑定。在某些情况下，我们可能需要对数据源进行自定义过滤，以便根据用户的输入来动态显示匹配的结果。本文将介绍如何在 Android 中使用 ArrayAdapter 进行自定义过滤，并提供一个案例代码来演示。

java
public class CustomArrayAdapter extends ArrayAdapter implements Filterable {
    private ArrayList mData;
    private ArrayList mFilteredData;
    public CustomArrayAdapter(Context context, int resource, ArrayList data) {
        super(context, resource, data);
        mData = data;
        mFilteredData = new ArrayList<>(data);
    }
    @Override
    public Filter getFilter() {
        return new Filter() {
            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                FilterResults results = new FilterResults();
                ArrayList filteredList = new ArrayList<>();
                if (constraint == null || constraint.length() == 0) {
                    filteredList.addAll(mData);
                } else {
                    String filterPattern = constraint.toString().toLowerCase().trim();
                    for (String item : mData) {
                        if (item.toLowerCase().contains(filterPattern)) {
                            filteredList.add(item);
                        }
                    }
                }
                results.values = filteredList;
                results.count = filteredList.size();
                return results;
            }
            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                mFilteredData.clear();
                mFilteredData.addAll((ArrayList) results.values);
                notifyDataSetChanged();
            }
        };
    }
    @Override
    public String convertResultToString(Object resultValue) {
        return (String) resultValue;
    }
    @Override
    public int getCount() {
        return mFilteredData.size();
    }
    @Override
    public String getItem(int position) {
        return mFilteredData.get(position);
    }
}

xml
    android:id="@+id/autoCompleteTextView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

java
public class MainActivity extends AppCompatActivity {
    private AutoCompleteTextView mAutoCompleteTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ArrayList cities = new ArrayList<>();
        cities.add("北京");
        cities.add("上海");
        cities.add("广州");
        cities.add("深圳");
        cities.add("杭州");
        CustomArrayAdapter adapter = new CustomArrayAdapter(this, android.R.layout.simple_dropdown_item_1line, cities);
        mAutoCompleteTextView = findViewById(R.id.autoCompleteTextView);
        mAutoCompleteTextView.setAdapter(adapter);
    }
}