android AutoCompleteTextView控件的使用

<AutoCompleteTextView
android:id="@+id/autoCompleteTextView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:text="AutoCompleteTextView" >

<requestFocus />
</AutoCompleteTextView>

private final String[] books = new String[] {"a", "ab", "abc", "abcd"};
private AutoCompleteTextView auto;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
auto = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1);
ArrayAdapter<String> av = new ArrayAdapter<String>(MainActivity.this,
android.R.layout.simple_dropdown_item_1line, books);
auto.setAdapter(av);
auto.setThreshold(1);

auto.addTextChangedListener(new TextWatcher() {

@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// TODO Auto-generated method stub

}

@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub

}

@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub

}
});
}