How to create a custom ListView with "extends Activity"?

I am learning 开发者_开发问答android programming, I was able to create a custom ListView with:

public class project1 extends ListActivity
{
....
}

With a xml file for the custom layout. i would like to know how to do the same thing but with

public class project1 extends Activity

    {
    ....
    }

All the tutorials I looked at use extends ListActivity, I know that its there to make things simpler, but for the sake of learning how to do it the hard way???

---

Have a look at this tutorial. http://techdroid.kbeanie.com/2009/07/custom-listview-for-android.html

Go thru this post. It is advanced some what : Lazy load of images in ListView

Edited According to your comment :

Consider example of displaying list of countries and their abbreviated names

First for Custom ListView you have to create an xml file representing your listview :

 <?xml version="1.0" encoding="utf-8"?>
 <!--main.xml-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ffccd0"
>
     <TextView
        android:text="Countries List"
        android:textColor="#b3000d"
        android:gravity="center_vertical|center_horizontal"
        android:textSize="26dip"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:background="#ffb0b6"
        android:layout_marginBottom="5dip"
        android:typeface="sans"/>
<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#570000">
    <TextView android:id="@+id/tv_1"
        android:textColor="#FFFFFF"
        android:gravity="center_vertical|left"
        android:textSize="16dip"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:typeface="serif"
        android:layout_width="70dip"
        android:paddingLeft="20dip"
        android:text="Abbr">
    </TextView>
    <TextView android:id="@+id/tv_2"
        android:textColor="#FFFFFF"
        android:gravity="center_vertical|left"
        android:textSize="16dip"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:typeface="serif"
        android:layout_width="200dip"
        android:layout_toRightOf="@+id/tv_1"
        android:text="Countries">
    </TextView>

</RelativeLayout>
<ListView
    android:id="@+id/lv_country"
    android:layout_height="wrap_content"
    android:layout_width="fill_parent"
    android:cacheColorHint="#00000000">
</ListView>
 </LinearLayout>

Now you have to create an xml file representing a row of list item. This is my row.xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content"
android:gravity="left|center"
android:layout_width="wrap_content"
android:paddingBottom="10px"
android:paddingTop="10px"
android:paddingLeft="3px">
 <TextView
    android:id="@+id/TextView01"
    android:layout_width="70dip"
    android:scrollHorizontally="true"
    android:layout_height="wrap_content"
    android:gravity="left"
    android:layout_weight="1"
    android:singleLine="true"
    android:textSize="15dip"
    android:textStyle="bold"
    android:textColor="#d08021"
    android:paddingLeft="20dip">
 </TextView>
 <TextView
    android:id="@+id/TextView02"
    android:layout_weight="2"
    android:layout_width="200dip"
    android:scrollHorizontally="true"
    android:layout_height="wrap_content"
    android:gravity="left"
    android:singleLine="true"
    android:layout_marginLeft="10dip"
    android:textSize="15dip"
    android:textStyle="bold"
    android:textColor="#7f0000">
 </TextView>
</LinearLayout>

As you want to display array of strings in ListView, i have used static Array of Strings and stored in CountriesList.java file.

This is my CountriesList.java file :

public class CountriesList {
public static String[] countries = { "Afghanistan", "Albania Albania Albania AlbaniaAlbaniaAlbaniaAlbania Albania ", "Algeria",
        "American Samoa", "Andorra", "Angola", "Anguilla", "Antarctica",
        "Antigua and Barbuda", "Argentina", "Armenia", "Aruba",
        "Australia", "Austria", "Azerbaijan", "Bahamas", "Bahrain",
        "Bangladesh", "Barbados", "Belarus", "Belgium", "Belize", "Benin",
        "Bermuda", "Bhutan", "Bolivia", "Bosnia and Herzegovina",
        "Botswana", "Bouvet Island", "Brazil",
        "British Indian Ocean Territory", "Brunei Darussalam", "Bulgaria",
        "Burkina Faso", "Burundi", "Cambodia", "Cameroon", "Canada",
        "Cape Verde", "Cayman Islands", "Central African Republic", "Chad",
        "Chile", "China", "Christmas Island", "Cocos (Keeling) Islands",
        "Colombia", "Comoros", "Congo",
        "Congo, the Democratic Republic of the", "Cook Islands",
        "Costa Rica", "Cote D'Ivoire", "Croatia", "Cuba", "Cyprus",
        "Czech Republic", "Denmark", "Djibouti", "Dominica",
        "Dominican Republic", "Ecuador", "Egypt", "El Salvador",
        "Equatorial Guinea", "Eritrea", "Estonia", "Ethiopia",
        "Falkland Islands (Malvinas)", "Faroe Islands", "Fiji", "Finland",
        "France", "French Guiana", "French Polynesia",
        "French Southern Territories", "Gabon", "Gambia", "Georgia",
        "Germany", "Ghana", "Gibraltar", "Greece", "Greenland", "Grenada",
        "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau",
        "Guyana", "Haiti", "Heard Island and Mcdonald Islands",
        "Holy See (Vatican City State)", "Honduras", "Hong Kong",
        "Hungary", "Iceland", "India", "Indonesia",
        "Iran, Islamic Republic of", "Iraq", "Ireland", "Israel", "Italy",
        "Jamaica", "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati",
        "Korea, Democratic People's Republic of", "Korea, Republic of",
        "Kuwait", "Kyrgyzstan", "Lao People's Democratic Republic",
        "Latvia", "Lebanon", "Lesotho", "Liberia",
        "Libyan Arab Jamahiriya", "Liechtenstein", "Lithuania",
        "Luxembourg", "Macao",
        "Macedonia, the Former Yugoslav Republic of", "Madagascar",
        "Malawi", "Malaysia", "Maldives", "Mali", "Malta",
        "Marshall Islands", "Martinique", "Mauritania", "Mauritius",
        "Mayotte", "Mexico", "Micronesia, Federated States of",
        "Moldova, Republic of", "Monaco", "Mongolia", "Montserrat",
        "Morocco", "Mozambique", "Myanmar", "Namibia", "Nauru", "Nepal",
        "Netherlands", "Netherlands Antilles", "New Caledonia",
        "New Zealand", "Nicaragua", "Niger", "Nigeria", "Niue",
        "Norfolk Island", "Northern Mariana Islands", "Norway", "Oman",
        "Pakistan", "Palau", "Palestinian Territory, Occupied", "Panama",
        "Papua New Guinea", "Paraguay", "Peru", "Philippines", "Pitcairn",
        "Poland", "Portugal", "Puerto Rico", "Qatar", "Reunion", "Romania",
        "Russian Federation", "Rwanda", "Saint Helena",
        "Saint Kitts and Nevis", "Saint Lucia",
        "Saint Pierre and Miquelon", "Saint Vincent and the Grenadines",
        "Samoa", "San Marino", "Sao Tome and Principe", "Saudi Arabia",
        "Senegal", "Serbia and Montenegro", "Seychelles", "Sierra Leone",
        "Singapore", "Slovakia", "Slovenia", "Solomon Islands", "Somalia",
        "South Africa", "South Georgia and the South Sandwich Islands",
        "Spain", "Sri Lanka", "Sudan", "Suriname",
        "Svalbard and Jan Mayen", "Swaziland", "Sweden", "Switzerland",
        "Syrian Arab Republic", "Taiwan, Province of China", "Tajikistan",
        "Tanzania, United Republic of", "Thailand", "Timor-Leste", "Togo",
        "Tokelau", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey",
        "Turkmenistan", "Turks and Caicos Islands", "Tuvalu", "Uganda",
        "Ukraine", "United Arab Emirates", "United Kingdom",
        "United States", "United States Minor Outlying Islands", "Uruguay",
        "Uzbekistan", "Vanuatu", "Venezuela", "Viet Nam",
        "Virgin Islands, British", "Virgin Islands, U.s.",
        "Wallis and Futuna", "Western Sahara", "Yemen", "Zambia",
        "Zimbabwe" };
public static String[] abbreviations = { "AF Western Sahara Western SaharaWestern Sahara Western SaharaWestern Sahara", "AL", "DZ", "AS", "AD", "AO", "AI", "AQ",
        "AG", "AR", "AM", "AW", "AU", "AT", "AZ", "BS", "BH", "BD", "BB",
        "BY", "BE", "BZ", "BJ", "BM", "BT", "BO", "BA", "BW", "BV", "BR",
        "IO", "BN", "BG", "BF", "BI", "KH", "CM", "CA", "CV", "KY", "CF",
        "TD", "CL", "CN", "CX", "CC", "CO", "KM", "CG", "CD", "CK", "CR",
        "CI", "HR", "CU", "CY", "CZ", "DK", "DJ", "DM", "DO", "EC", "EG",
        "SV", "GQ", "ER", "EE", "ET", "FK", "FO", "FJ", "FI", "FR", "GF",
        "PF", "TF", "GA", "GM", "GE", "DE", "GH", "GI", "GR", "GL", "GD",
        "GP", "GU", "GT", "GN", "GW", "GY", "HT", "HM", "VA", "HN", "HK",
        "HU", "IS", "IN", "ID", "IR", "IQ", "IE", "IL", "IT", "JM", "JP",
        "JO", "KZ", "KE", "KI", "KP", "KR", "KW", "KG", "LA", "LV", "LB",
        "LS", "LR", "LY", "LI", "LT", "LU", "MO", "MK", "MG", "MW", "MY",
        "MV", "ML", "MT", "MH", "MQ", "MR", "MU", "YT", "MX", "FM", "MD",
        "MC", "MN", "MS", "MA", "MZ", "MM", "NA", "NR", "NP", "NL", "AN",
        "NC", "NZ", "NI", "NE", "NG", "NU", "NF", "MP", "NO", "OM", "PK",
        "PW", "PS", "PA", "PG", "PY", "PE", "PH", "PN", "PL", "PT", "PR",
        "QA", "RE", "RO", "RU", "RW", "SH", "KN", "LC", "PM", "VC", "WS",
        "SM", "ST", "SA", "SN", "CS", "SC", "SL", "SG", "SK", "SI", "SB",
        "SO", "ZA", "GS", "ES", "LK", "SD", "SR", "SJ", "SZ", "SE", "CH",
        "SY", "TW", "TJ", "TZ", "TH", "TL", "TG", "TK", "TO", "TT", "TN",
        "TR", "TM", "TC", "TV", "UG", "UA", "AE", "GB", "US", "UM", "UY",
        "UZ", "VU", "VE", "VN", "VG", "VI", "WF", "EH", "YE", "ZM", "ZW" };
 }

As you are customizing the ListView, you have create another class extending BaseAdapter, working as a controller of ListView.

So here is my EfficientAdapter.java file :

private static class EfficientAdapter extends BaseAdapter {
    private LayoutInflater mInflater;

    public EfficientAdapter(Context context) {
        mInflater = LayoutInflater.from(context);
    }

    public int getCount() {
        return CountriesList.abbreviations.length;
    }

    public Object getItem(int position) {
        return position;
    }

    public long getItemId(int position) {
        return position;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.row, null);
            holder = new ViewHolder();
            holder.text1 = (TextView) convertView
                    .findViewById(R.id.TextView01);
            holder.text2 = (TextView) convertView
                    .findViewById(R.id.TextView02);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.text1.setText(CountriesList.abbreviations[position]);
        holder.text2.setText(CountriesList.countries[position]);

        return convertView;
    }

    static class ViewHolder {
        TextView text1;
        TextView text2;
    }
}

Now the last thing remaining is your Activity Class. Here it is :

public class MyList extends Activity {
/** Called when the activity is first created. */
ListView listView;
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    listView = (ListView) findViewById(R.id.lv_country);
    listView.setAdapter(new EfficientAdapter(this));

            listView.setOnItemClickListener(        
            new OnItemClickListener()
            {
                @Override
                public void onItemClick(AdapterView<?> arg0, View view,int position, long arg3) {
                    // TODO Auto-generated method stub
                    Toast.makeText(getApplicationContext(),"You Selected Item "+Integer.toString(position), Toast.LENGTH_LONG).show();          
                }       
            }
    );
}

---

It is not really anything harder when extending Activity.

The only thing that changes is that you first have to grab a reference to your ListView defined in your XML layout file using the findViewById() method.

ListView mListView = (ListView)findViewById(R.id.my_listview);

Defining a custom Adapter works the same. Just create it and assign your ListView that adapter.

mListView.setAdapter(mAdapter);

Thats it. Nothing special about it.

---

public class ListViewLoader extends ListActivity
        implements LoaderManager.LoaderCallbacks<Cursor> {

    // This is the Adapter being used to display the list's data
    SimpleCursorAdapter mAdapter;

    // These are the Contacts rows that we will retrieve
    static final String[] PROJECTION = new String[] {ContactsContract.Data._ID,
            ContactsContract.Data.DISPLAY_NAME};

    // This is the select criteria
    static final String SELECTION = "((" + 
            ContactsContract.Data.DISPLAY_NAME + " NOTNULL) AND (" +
            ContactsContract.Data.DISPLAY_NAME + " != '' ))";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Create a progress bar to display while the list loads
        ProgressBar progressBar = new ProgressBar(this);
        progressBar.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
                LayoutParams.WRAP_CONTENT, Gravity.CENTER));
        progressBar.setIndeterminate(true);
        getListView().setEmptyView(progressBar);

        // Must add the progress bar to the root of the layout
        ViewGroup root = (ViewGroup) findViewById(android.R.id.content);
        root.addView(progressBar);

        // For the cursor adapter, specify which columns go into which views
        String[] fromColumns = {ContactsContract.Data.DISPLAY_NAME};
        int[] toViews = {android.R.id.text1}; // The TextView in simple_list_item_1

        // Create an empty adapter we will use to display the loaded data.
        // We pass null for the cursor, then update it in onLoadFinished()
        mAdapter = new SimpleCursorAdapter(this, 
                android.R.layout.simple_list_item_1, null,
                fromColumns, toViews, 0);
        setListAdapter(mAdapter);

        // Prepare the loader.  Either re-connect with an existing one,
        // or start a new one.
        getLoaderManager().initLoader(0, null, this);
    }

    // Called when a new Loader needs to be created
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        // Now create and return a CursorLoader that will take care of
        // creating a Cursor for the data being displayed.
        return new CursorLoader(this, ContactsContract.Data.CONTENT_URI,
                PROJECTION, SELECTION, null, null);
    }

    // Called when a previously created loader has finished loading
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        // Swap the new cursor in.  (The framework will take care of closing the
        // old cursor once we return.)
        mAdapter.swapCursor(data);
    }

    // Called when a previously created loader is reset, making the data unavailable
    public void onLoaderReset(Loader<Cursor> loader) {
        // This is called when the last Cursor provided to onLoadFinished()
        // above is about to be closed.  We need to make sure we are no
        // longer using it.
        mAdapter.swapCursor(null);
    }

    @Override 
    public void onListItemClick(ListView l, View v, int position, long id) {
        // Do something when a list item is clicked
    }
}