我一直在为 AutoCompleteTextView 创建自定义 ArrayAdapter 时遇到困难，尽管在 Internet 上找到以下代码，但仍会出现此类错误：
所以对于那些和我有同样问题的人，我建议使用 BaseAdapter 来代替 AutoCompleteTextView。
【问题讨论】：
标签： android android-arrayadapter baseadapter autocompletetextview
以下是我使用 ArrayAdapter 的工作代码。
假设来自 Web 服务的响应数据如下所示：
[
{
"id": "1",
"name": "Information Technology"
},
{
"id": "2",
"name": "Human Resources"
},
{
"id": "3",
"name": "Marketing and PR"
},
{
"id": "4",
"name": "Research and Developement"
}
]
然后在您的 Android 客户端中：
部门类：
public class Department {
public int id;
public String name;
}
自定义适配器类：
public class DepartmentArrayAdapter extends ArrayAdapter<Department> {
private final Context mContext;
private final List<Department> mDepartments;
private final List<Department> mDepartmentsAll;
private final int mLayoutResourceId;
public DepartmentArrayAdapter(Context context, int resource, List<Department> departments) {
super(context, resource, departments);
this.mContext = context;
this.mLayoutResourceId = resource;
this.mDepartments = new ArrayList<>(departments);
this.mDepartmentsAll = new ArrayList<>(departments);
}
public int getCount() {
return mDepartments.size();
}
public Department getItem(int position) {
return mDepartments.get(position);
}
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
try {
if (convertView == null) {
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(mLayoutResourceId, parent, false);
}
Department department = getItem(position);
TextView name = (TextView) convertView.findViewById(R.id.textView);
name.setText(department.name);
} catch (Exception e) {
e.printStackTrace();
}
return convertView;
}
@Override
public Filter getFilter() {
return new Filter() {
@Override
public String convertResultToString(Object resultValue) {
return ((Department) resultValue).name;
}
@Override
protected FilterResults performFiltering(CharSequence constraint) {
FilterResults filterResults = new FilterResults();
List<Department> departmentsSuggestion = new ArrayList<>();
if (constraint != null) {
for (Department department : mDepartmentsAll) {
if (department.name.toLowerCase().startsWith(constraint.toString().toLowerCase())) {
departmentsSuggestion.add(department);
}
}
filterResults.values = departmentsSuggestion;
filterResults.count = departmentsSuggestion.size();
}
return filterResults;
}
@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
mDepartments.clear();
if (results != null && results.count > 0) {
// avoids unchecked cast warning when using mDepartments.addAll((ArrayList<Department>) results.values);
for (Object object : (List<?>) results.values) {
if (object instanceof Department) {
mDepartments.add((Department) object);
}
}
notifyDataSetChanged();
} else if (constraint == null) {
// no filter, add entire original list back in
mDepartments.addAll(mDepartmentsAll);
notifyDataSetInvalidated();
}
}
};
}
}
主要活动：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAutoCompleteTextView = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);
mAutoCompleteTextView.setThreshold(1);
new DepartmentRequest().execute();
}
private class DepartmentRequest extends AsyncTask<Void, Void, JSONArray> {
@Override
protected JSONArray doInBackground(Void... voids) {
OkHttpJsonArrayRequest request = new OkHttpJsonArrayRequest();
try {
return request.get("http://...");
} catch (IOException | JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(JSONArray jsonArray) {
super.onPostExecute(jsonArray);
if (jsonArray != null && jsonArray.length() > 0) {
Gson gson = new Gson();
Department[] departments = gson.fromJson(jsonArray.toString(), Department[].class);
mDepartmentList = Arrays.asList(departments);
mDepartmentArrayAdapter = new DepartmentArrayAdapter(mContext, R.layout.simple_text_view, mDepartmentList);
mAutoCompleteTextView.setAdapter(mDepartmentArrayAdapter);
}
}
}
private class OkHttpJsonArrayRequest {
OkHttpClient client = new OkHttpClient();
// HTTP GET REQUEST
JSONArray get(String url) throws IOException, JSONException {
Request request = new Request.Builder()
.url(url)
.build();
Response response = client.newCall(request).execute();
return new JSONArray(response.body().string());
}
}
截图如下：
希望这会有所帮助！
【讨论】：
自定义 BaseAdapter 类
public class ObjectAdapter extends BaseAdapter implements Filterable {
private Context context;
private ArrayList<Object> originalList;
private ArrayList<Object> suggestions = new ArrayList<>();
private Filter filter = new CustomFilter();
/**
* @param context Context
* @param originalList Original list used to compare in constraints.
*/
public ObjectAdapter(Context context, ArrayList<Object> originalList) {
this.context = context;
this.originalList = originalList;
}
@Override
public int getCount() {
return suggestions.size(); // Return the size of the suggestions list.
}
@Override
public Object getItem(int position) {
return suggestions.get(position).getCountryName();
}
@Override
public long getItemId(int position) {
return 0;
}
/**
* This is where you inflate the layout and also where you set what you want to display.
* Here we also implement a View Holder in order to recycle the views.
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = LayoutInflater.from(context);
ViewHolder holder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.adapter_autotext,
parent,
false);
holder = new ViewHolder();
holder.autoText = (TextView) convertView.findViewById(R.id.autoText);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.autoText.setText(suggestions.get(position).getCountryName());
return convertView;
}
@Override
public Filter getFilter() {
return filter;
}
private static class ViewHolder {
TextView autoText;
}
/**
* Our Custom Filter Class.
*/
private class CustomFilter extends Filter {
@Override
protected FilterResults performFiltering(CharSequence constraint) {
suggestions.clear();
if (originalList != null && constraint != null) { // Check if the Original List and Constraint aren't null.
for (int i = 0; i < originalList.size(); i++) {
if (originalList.get(i).getCountryName().toLowerCase().contains(constraint)) { // Compare item in original list if it contains constraints.
suggestions.add(originalList.get(i)); // If TRUE add item in Suggestions.
}
}
}
FilterResults results = new FilterResults(); // Create new Filter Results and return this to publishResults;
results.values = suggestions;
results.count = suggestions.size();
return results;
}
@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
if (results.count > 0) {
notifyDataSetChanged();
} else {
notifyDataSetInvalidated();
}
}
}
}
主要活动类
public class MainActivity extends AppCompatActivity{
private SGetCountryListAdapter countryAdapter;
private ArrayList<SGetCountryList> countryList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
country = (AutoCompleteTextView) findViewById(R.id.country);
countryAdapter = new SGetCountryListAdapter(getApplicationContext(),
ConnectionParser.SGetCountryList);
country.setAdapter(countryAdapter);
country.setThreshold(1);
}
}
下拉布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/autoText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="16dp"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:textColor="@color/black" />
</LinearLayout>
我的原始列表有来自网络服务的数据，所以我们假设它已经有数据。当然，您可以通过添加更多视图来自定义下拉菜单，只是不要忘记更新适配器以合并新视图。
【讨论】：