AutoCompleteTextView 在做搜索功能时常常被应用到，它的好处是根据用户输入的信息实现后缀信息的提示功能。
此控件通常的用法是
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_dropdown_item_1line, COUNTRIES);
AutoCompleteTextView textView = (AutoCompleteTextView) findViewById(R.id.edit);
textView.setAdapter(adapter);
其中 adapter 可以任意构造， COUNTRIES 是数据源，如 COUNTTRIES＝["aaaaa","bbbbbb","cccccc"], 那么当在框中输入a时，则AutoCompleteTextView 自动提示aaaaa，这种根据数据源的值来提示做起来很是简单，略过。
下面讲一下自定义匹配规则的提示，假如现在有这么一个需求，根据输入城市的拼音，来提示相对应的城市列表，这样就不能按上述方式来做了，因为你输入的信息并不是数据源的信息，所以你必须得自定义匹配规则来找出对应的城市提示，思路是这样的：先把所有的城市及对应的拼音放在一个Hashtable里，然后自己实现一个 Adapter 来加载这些数据源，当用户输入每一个拼音字符时，需实时监听到（系统主动监听），然后去Hashtable里找到对应的城市设置到Adapter里，这样在控件的下拉列表中就可以看到所需的城市列表提示，我贴一段 Adapter代码供大家参考一下，定义了一个SearchCityAdapter extends BaseAdapter implements Filterable,其中Filterable接口主要是用来实现自定义匹配规则的，它定义了getFilter()方法
public Filter getFilter() {
if (mFilter == null) {
mFilter = new CityArrayFilter();
}
return mFilter;
}
此方法是为了得到一个过滤器，也就是自定义匹配规则的过滤器即CityArrayFilter，它的实现是
/**
* <p>An array filter constrains the content of the array adapter with
* a prefix. Each item that does not start with the supplied prefix
* is removed from the list.</p>
*/
private class CityArrayFilter extends Filter {
/**
* The method is called when receive softkeybord entry's char
*/
@Override
protected FilterResults performFiltering(CharSequence prefix) {
if(Log.DEBUG.get()) {
Log.i(tag, "CityArrayFilter : performFiltering >>>>>>>>>>> prefix = "+prefix);
}
FilterResults results = new FilterResults();
if (mOriginalValues == null) {
synchronized (mLock) {
mOriginalValues = new ArrayList<T>(mObjects);
}
}
if (prefix == null || prefix.length() == 0) {
synchronized (mLock) {
ArrayList<T> list = new ArrayList<T>(mOriginalValues);
results.values = list;
results.count = list.size();
}
} else {
String prefixString = prefix.toString().toLowerCase();
final ArrayList<T> values = mOriginalValues;
final int count = values.size();
final ArrayList<T> newValues = new ArrayList<T>(count);
final Enumeration enumeration = ChooseCityActivity.ht.keys();
String key;
String[] keyPart;
while(enumeration.hasMoreElements()) {
key = (String)enumeration.nextElement();
keyPart = key.split("-");
Log.i(tag, ">>>>>>>>>>>>>>>>>>> prefixString = "+prefixString+" key = "+key);
if(prefixString.length() == 1 && keyPart[1].startsWith(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
} else if (prefixString.length() == 2) {
if(keyPart[2].equals(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
if(newValues.size() == 0 && keyPart[1].startsWith(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
} else if (prefixString.length() == 3) {
if(keyPart[0].equals(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
if(newValues.size() == 0 && keyPart[1].startsWith(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
}
}
/*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;
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) {
if(Log.DEBUG.get()) {
Log.i(tag, "CityArrayFilter : publishResults >>>>>>>>>>> results.values = "+results.values);
}
mObjects = (List<T>) results.values;
if (results.count > 0) {
notifyDataSetChanged();
} else {
notifyDataSetInvalidated();
}
}
}
while()里是匹配规则，FilterResults 装的是匹配后的城市，最终它将作为 getView() 的数据源显示在AutoCompleteTextView 的下拉列表里，prefix 指的是监听到的用户输入的拼音字符，通过这个字符去Hashtable里查找对应的城市，具体描述请看看下面的Adapter的完整代码
public class SearchCityAdapter<T> extends BaseAdapter implements Filterable {
private static final String tag = Log.getTag(SearchCityAdapter.class);
/**
* Contains the list of objects that represent the data of this ArrayAdapter.
* The content of this list is referred to as "the array" in the documentation.
*/
private List<T> mObjects;
/**
* Lock used to modify the content of {@link #mObjects}. Any write operation
* performed on the array should be synchronized on this lock. This lock is also
* used by the filter (see {@link #getFilter()} to make a synchronized copy of
* the original array of data.
*/
private final Object mLock = new Object();
/**
* The resource indicating what views to inflate to display the content of this
* array adapter.
*/
private int mResource;
/**
* The resource indicating what views to inflate to display the content of this
* array adapter in a drop down widget.
*/
private int mDropDownResource;
/**
* If the inflated resource is not a TextView, {@link #mFieldId} is used to find
* a TextView inside the inflated views hierarchy. This field must contain the
* identifier that matches the one defined in the resource file.
*/
private int mFieldId = 0;
/**
* Indicates whether or not {@link #notifyDataSetChanged()} must be called whenever
* {@link #mObjects} is modified.
*/
private boolean mNotifyOnChange = true;
private Context mContext;
private ArrayList<T> mOriginalValues;
private CityArrayFilter mFilter;
private LayoutInflater mInflater;
/**
* Constructor
*
* @param context The current context.
* @param textViewResourceId The resource ID for a layout file containing a TextView to use when
* instantiating views.
*/
public SearchCityAdapter(Context context, int textViewResourceId) {
init(context, textViewResourceId, 0, new ArrayList<T>());
}
/**
* Constructor
*
* @param context The current context.
* @param resource The resource ID for a layout file containing a layout to use when
* instantiating views.
* @param textViewResourceId The id of the TextView within the layout resource to be populated
*/
public SearchCityAdapter(Context context, int resource, int textViewResourceId) {
init(context, resource, textViewResourceId, new ArrayList<T>());
}
/**
* Constructor
*
* @param context The current context.
* @param textViewResourceId The resource ID for a layout file containing a TextView to use when
* instantiating views.
* @param objects The objects to represent in the ListView.
*/
public SearchCityAdapter(Context context, int textViewResourceId, T[] objects) {
init(context, textViewResourceId, 0, Arrays.asList(objects));
}
/**
* Constructor
*
* @param context The current context.
* @param resource The resource ID for a layout file containing a layout to use when
* instantiating views.
* @param textViewResourceId The id of the TextView within the layout resource to be populated
* @param objects The objects to represent in the ListView.
*/
public SearchCityAdapter(Context context, int resource, int textViewResourceId, T[] objects) {
init(context, resource, textViewResourceId, Arrays.asList(objects));
}
/**
* Constructor
*
* @param context The current context.
* @param textViewResourceId The resource ID for a layout file containing a TextView to use when
* instantiating views.
* @param objects The objects to represent in the ListView.
*/
public SearchCityAdapter(Context context, int textViewResourceId, List<T> objects) {
init(context, textViewResourceId, 0, objects);
}
/**
* Constructor
*
* @param context The current context.
* @param resource The resource ID for a layout file containing a layout to use when
* instantiating views.
* @param textViewResourceId The id of the TextView within the layout resource to be populated
* @param objects The objects to represent in the ListView.
*/
public SearchCityAdapter(Context context, int resource, int textViewResourceId, List<T> objects) {
init(context, resource, textViewResourceId, objects);
}
/**
* Adds the specified object at the end of the array.
*
* @param object The object to add at the end of the array.
*/
public void add(T object) {
if (mOriginalValues != null) {
synchronized (mLock) {
mOriginalValues.add(object);
if (mNotifyOnChange) notifyDataSetChanged();
}
} else {
mObjects.add(object);
if (mNotifyOnChange) notifyDataSetChanged();
}
}
/**
* Adds the specified Collection at the end of the array.
*
* @param collection The Collection to add at the end of the array.
*/
public void addAll(Collection<? extends T> collection) {
if (mOriginalValues != null) {
synchronized (mLock) {
mOriginalValues.addAll(collection);
if (mNotifyOnChange) notifyDataSetChanged();
}
} else {
mObjects.addAll(collection);
if (mNotifyOnChange) notifyDataSetChanged();
}
}
/**
* Adds the specified items at the end of the array.
*
* @param items The items to add at the end of the array.
*/
public void addAll(T ... items) {
if (mOriginalValues != null) {
synchronized (mLock) {
for (T item : items) {
mOriginalValues.add(item);
}
if (mNotifyOnChange) notifyDataSetChanged();
}
} else {
for (T item : items) {
mObjects.add(item);
}
if (mNotifyOnChange) notifyDataSetChanged();
}
}
/**
* Inserts the specified object at the specified index in the array.
*
* @param object The object to insert into the array.
* @param index The index at which the object must be inserted.
*/
public void insert(T object, int index) {
if (mOriginalValues != null) {
synchronized (mLock) {
mOriginalValues.add(index, object);
if (mNotifyOnChange) notifyDataSetChanged();
}
} else {
mObjects.add(index, object);
if (mNotifyOnChange) notifyDataSetChanged();
}
}
/**
* Removes the specified object from the array.
*
* @param object The object to remove.
*/
public void remove(T object) {
if (mOriginalValues != null) {
synchronized (mLock) {
mOriginalValues.remove(object);
}
} else {
mObjects.remove(object);
}
if (mNotifyOnChange) notifyDataSetChanged();
}
/**
* Remove all elements from the list.
*/
public void clear() {
if (mOriginalValues != null) {
synchronized (mLock) {
mOriginalValues.clear();
}
} else {
mObjects.clear();
}
if (mNotifyOnChange) notifyDataSetChanged();
}
/**
* Sorts the content of this adapter using the specified comparator.
*
* @param comparator The comparator used to sort the objects contained
* in this adapter.
*/
public void sort(Comparator<? super T> comparator) {
Collections.sort(mObjects, comparator);
if (mNotifyOnChange) notifyDataSetChanged();
}
/**
* {@inheritDoc}
*/
@Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
mNotifyOnChange = true;
}
/**
* Control whether methods that change the list ({@link #add},
* {@link #insert}, {@link #remove}, {@link #clear}) automatically call
* {@link #notifyDataSetChanged}. If set to false, caller must
* manually call notifyDataSetChanged() to have the changes
* reflected in the attached view.
*
* The default is true, and calling notifyDataSetChanged()
* resets the flag to true.
*
* @param notifyOnChange if true, modifications to the list will
* automatically call {@link
* #notifyDataSetChanged}
*/
public void setNotifyOnChange(boolean notifyOnChange) {
mNotifyOnChange = notifyOnChange;
}
private void init(Context context, int resource, int textViewResourceId, List<T> objects) {
mContext = context;
mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mResource = mDropDownResource = resource;
mObjects = objects;
mFieldId = textViewResourceId;
for (T t : objects) {
Log.i(tag, ">>>>>>>>>>>>> t = "+t);
}
}
/**
* Returns the context associated with this array adapter. The context is used
* to create views from the resource passed to the constructor.
*
* @return The Context associated with this adapter.
*/
public Context getContext() {
return mContext;
}
/**
* {@inheritDoc}
*/
public int getCount() {
return mObjects.size();
}
/**
* {@inheritDoc}
*/
public T getItem(int position) {
return mObjects.get(position);
}
/**
* Returns the position of the specified item in the array.
*
* @param item The item to retrieve the position of.
*
* @return The position of the specified item.
*/
public int getPosition(T item) {
return mObjects.indexOf(item);
}
/**
* {@inheritDoc}
*/
public long getItemId(int position) {
return position;
}
/**
* {@inheritDoc}
*/
public View getView(int position, View convertView, ViewGroup parent) {
return createViewFromResource(position, convertView, parent, mResource);
}
private View createViewFromResource(int position, View convertView, ViewGroup parent,
int resource) {
View view;
TextView text;
if (convertView == null) {
view = mInflater.inflate(resource, parent, false);
} else {
view = convertView;
}
try {
if (mFieldId == 0) {
// If no custom field is assigned, assume the whole resource is a TextView
text = (TextView) view;
} else {
// Otherwise, find the TextView field within the layout
text = (TextView) view.findViewById(mFieldId);
}
} catch (ClassCastException e) {
Log.e("SearchCityAdapter", "You must supply a resource ID for a TextView");
throw new IllegalStateException(
"SearchCityAdapter requires the resource ID to be a TextView", e);
}
T item = getItem(position);
Log.i(tag, ">>>>>>>>>>>>>> position = "+position+" item = "+item);
if (item instanceof CharSequence) {
text.setText((CharSequence)item);
} else {
text.setText(item.toString());
}
return view;
}
/**
* <p>Sets the layout resource to create the drop down views.</p>
*
* @param resource the layout resource defining the drop down views
* @see #getDropDownView(int, android.view.View, android.view.ViewGroup)
*/
public void setDropDownViewResource(int resource) {
this.mDropDownResource = resource;
}
/**
* {@inheritDoc}
*/
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
return createViewFromResource(position, convertView, parent, mDropDownResource);
}
/**
* Creates a new ArrayAdapter from external resources. The content of the array is
* obtained through {@link android.content.res.Resources#getTextArray(int)}.
*
* @param context The application's environment.
* @param textArrayResId The identifier of the array to use as the data source.
* @param textViewResId The identifier of the layout used to create views.
*
* @return An ArrayAdapter<CharSequence>.
*/
public static ArrayAdapter<CharSequence> createFromResource(Context context,
int textArrayResId, int textViewResId) {
CharSequence[] strings = context.getResources().getTextArray(textArrayResId);
return new ArrayAdapter<CharSequence>(context, textViewResId, strings);
}
/**
* {@inheritDoc}
*/
public Filter getFilter() {
if (mFilter == null) {
mFilter = new CityArrayFilter();
}
return mFilter;
}
/**
* <p>An array filter constrains the content of the array adapter with
* a prefix. Each item that does not start with the supplied prefix
* is removed from the list.</p>
*/
private class CityArrayFilter extends Filter {
/**
* The method is called when receive softkeybord entry's char
*/
@Override
protected FilterResults performFiltering(CharSequence prefix) {
if(Log.DEBUG.get()) {
Log.i(tag, "CityArrayFilter : performFiltering >>>>>>>>>>> prefix = "+prefix);
}
FilterResults results = new FilterResults();
if (mOriginalValues == null) {
synchronized (mLock) {
mOriginalValues = new ArrayList<T>(mObjects);
}
}
if (prefix == null || prefix.length() == 0) {
synchronized (mLock) {
ArrayList<T> list = new ArrayList<T>(mOriginalValues);
results.values = list;
results.count = list.size();
}
} else {
String prefixString = prefix.toString().toLowerCase();
final ArrayList<T> values = mOriginalValues;
final int count = values.size();
final ArrayList<T> newValues = new ArrayList<T>(count);
final Enumeration enumeration = ChooseCityActivity.ht.keys();
String key;
String[] keyPart;
while(enumeration.hasMoreElements()) {
key = (String)enumeration.nextElement();
keyPart = key.split("-");
Log.i(tag, ">>>>>>>>>>>>>>>>>>> prefixString = "+prefixString+" key = "+key);
if(prefixString.length() == 1 && keyPart[1].startsWith(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
} else if (prefixString.length() == 2) {
if(keyPart[2].equals(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
if(newValues.size() == 0 && keyPart[1].startsWith(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
} else if (prefixString.length() == 3) {
if(keyPart[0].equals(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
if(newValues.size() == 0 && keyPart[1].startsWith(prefixString)) {
newValues.add((T)ChooseCityActivity.ht.get(key));
}
}
}
/*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;
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) {
if(Log.DEBUG.get()) {
Log.i(tag, "CityArrayFilter : publishResults >>>>>>>>>>> results.values = "+results.values);
}
mObjects = (List<T>) results.values;
if (results.count > 0) {
notifyDataSetChanged();
} else {
notifyDataSetInvalidated();
}
}
}
}