Mark Murphy - Beginning Android

The search activity can have any look you want. In fact, other than watching for queries, a search activity looks, walks, and talks like any other activity in your system.

All the search activity needs to do differently is check the intents supplied to onCreate()(via getIntent()) and onNewIntent()to see if one is a search, and, if so, to do the search and display the results.

For example, let’s look at the Search/Loremsample application (available in the Source Code section of http://apress.com). This starts off as a clone of the list-of-lorem-ipsum-words application that we first built back when showing off the ListViewcontainer in Chapter 8, then with XML resources in Chapter 19. Now we update it to support searching the list of words for ones containing the search string.

The main activity and the search activity share a common layout: a ListViewplus a TextViewshowing the selected entry:

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

android:id="@+id/selection"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

/>

android:id="@android:id/list"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:drawSelectorOnTop="false"

/>

In terms of Java code, most of the guts of the activities are poured into an abstract LoremBaseclass:

abstract public classLoremBase extendsListActivity {

abstractListAdapter makeMeAnAdapter(Intent intent);

private static finalint LOCAL_SEARCH_ID = Menu.FIRST+1;

private static finalint GLOBAL_SEARCH_ID = Menu.FIRST+2;

private static finalint CLOSE_ID = Menu.FIRST+3;

TextView selection;

ArrayList items = newArrayList();

@Override

publicvoid onCreate(Bundle icicle) {

super. onCreate(icicle);

setContentView(R.layout.main);

selection = (TextView) findViewById(R.id.selection);

try{

XmlPullParser xpp = getResources(). getXml(R.xml.words);

while(xpp. getEventType()!=XmlPullParser.END_DOCUMENT) {

if(xpp. getEventType()==XmlPullParser.START_TAG) {

if(xpp. getName(). equals("word")) {

items. add(xpp. getAttributeValue(0));

}

}

xpp. next();

}

} catch(Throwable t) {

Toast

. makeText( this, "Request failed: " + t. toString(), 4000). show();

}

setDefaultKeyMode(DEFAULT_KEYS_SEARCH_LOCAL);

onNewIntent( getIntent());

}

@Override

publicvoid onNewIntent(Intent intent) {

ListAdapter adapter = makeMeAnAdapter(intent);

if(adapter== null) {

finish();

} else{

setListAdapter(adapter);

}

}

publicvoid onListItemClick(ListView parent, View v, int position,

long id) {

selection. setText(items. get(position). toString());

}

@Override

publicboolean onCreateOptionsMenu(Menu menu) {

menu. add(Menu.NONE, LOCAL_SEARCH_ID, Menu.NONE, "Local Search")

. setIcon(android.R.drawable.ic_search_category_default);

menu. add(Menu.NONE, GLOBAL_SEARCH_ID, Menu.NONE, "Global Search")

. setIcon(R.drawable.search). setAlphabeticShortcut(SearchManager.MENU_KEY);

menu. add(Menu.NONE, CLOSE_ID, Menu.NONE, "Close")

. setIcon(R.drawable.eject). setAlphabeticShortcut('c');

return( super. onCreateOptionsMenu(menu));

}

@Override

publicboolean onOptionsItemSelected(MenuItem item) {

switch(item. getItemId()) {

caseLOCAL_SEARCH_ID:

onSearchRequested();

return( true);

caseGLOBAL_SEARCH_ID:

startSearch( null, false, null, true);

return( true);

caseCLOSE_ID:

finish();

return( true);

}

return( super. onOptionsItemSelected(item));

}

}

This activity takes care of everything related to showing a list of words, even loading the words out of the XML resource. What it does not do is come up with the ListAdapterto put into the ListView— that is delegated to the subclasses.

The main activity — LoremDemo— just uses a ListAdapterfor the whole word list:

packagecom.commonsware.android.search;

importandroid.content.Intent;

importandroid.widget.ArrayAdapter;

importandroid.widget.ListAdapter;

public classLoremDemo extendsLoremBase {

@Override ListAdapter makeMeAnAdapter(Intent intent) {

return( newArrayAdapter( this,

android.R.layout.simple_list_item_1, items));

}

}

The search activity, though, does things a bit differently. First, it inspects the Intentsupplied to the abstract makeMeAnAdapter()method. That Intent comes from either onCreate()or onNewIntent(). If the intent is an ACTION_SEARCH, then we know this is a search. We can get the search query and, in the case of this silly demo, spin through the loaded list of words and find only those containing the search string. That list then gets wrapped in a ListAdapterand returned for display: