Basic android beginners ListView view (8)

I. ListView View:

ListView is used to display a list control.

Public class MainActivity extends ListActivity {String [] str = {"China", "France", "UK", "Switzerland", "Austria", "USA", "India ", "Vatican"}; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setListAdapter (new ArrayAdapter
 
  
(This, android. r. layout. simple_list_item_1, str);} @ Overrideprotected void onListItemClick (ListView l, View v, int position, long id) {// TODO Auto-generated method stubToast. makeText (this, "you clicked" + str [position], Toast. LENGTH_SHORT ). show ();}}
 

This is the most basic list of ListView implementations:

MainActivity extends the ListView class, while the ListView class extends the Activity class and displays a list of items by binding to a data source. Note that you do not need to add the ListView control to the layout file, because the ListView class already contains a ListView. In the onCreate () method, use setListAdapter () method to use a ListView to program the entire screen of the activity. ArrayAdapter object management is a string array displayed by ListView. When you click a list option in ListView, The onListItemClick () method is triggered to display a piece of toast information.

Running diagram:

We can store the strings to be displayed in strings. xml:

 
     
  
   
ListViewTest
      
  
   
Settings
      
  
   
Hello world!
      
          
   
    
China
           
   
    
France
           
   
    
UK
           
   
    
Switzerland
           
   
    
Austria
           
   
    
USA
           
   
    
India
           
   
    
Vatican
           
   
    
Maldives
       
  
 

MainActivity. java:

Public class MainActivity extends ListActivity {String [] str; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); str = getResources (). getStringArray (R. array. str); setListAdapter (new ArrayAdapter
 
  
(This, android. r. layout. simple_list_item_1, str);} @ Overrideprotected void onListItemClick (ListView l, View v, int position, long id) {// TODO Auto-generated method stubToast. makeText (this, "you clicked" + str [position], Toast. LENGTH_SHORT ). show ();}}
 

You can use the getResources () method to programmatically retrieve resources bound to an application.

Custom ListView + custom adapter (BaseAdapter ):

ListView layout:

MainActivity. java:

Public class MainActivity extends ListActivity {@ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); // set an Adapter and use the custom Adapter setListAdapter (new TextImageAdapter (this);} private class TextImageAdapter extends BaseAdapter {private Context mContext; public TextImageAdapter (Context context) {this. mContext = context;}/*** number of elements */public int getCount () {return left. length;} public Object getItem (int position) {return null;} public long getItemId (int position) {return 0 ;} // generate View public View getView (int position, View convertView, ViewGroup parent) elements displayed in ListView {// optimize ListView if (convertView = null) {convertView = LayoutInflater. from (mContext ). inflate (R. layout. activity_main, null); ItemViewCache viewCache = new ItemViewCache (); viewCache. mTextLeft = (TextView) convertView. findViewById (R. id. textLeft); viewCache. mTextRight = (TextView) convertView. findViewById (R. id. textRight); convertView. setTag (viewCache);} ItemViewCache cache = (ItemViewCache) convertView. getTag (); // set the text and image, and then return this View for the ListView Item display cache. mTextLeft. setText (left [position]); cache. mTextRight. setText (Right [position]); return convertView;} private static class ItemViewCache {public TextView mTextLeft; public TextView mTextRight ;} // TextView private String [] left = new String [] {"country", "Province", "region"} on the left of the screen "}; // TextView private String [] Right = new String [] {"China", "Shandong", "Binzhou "};}

We have defined the adapter here, which will be explained in detail later. Click events to add a list:

@ Overrideprotected void onListItemClick (ListView l, View v, int position, long id) {// TODO Auto-generated method stubToast. makeText (this, "you clicked" + left [position] + Right [position], Toast. LENGTH_SHORT ). show ();}

Running effect:

Zookeeper