Using Android ListView, ListActivity and ListFragment
This tutorial describes how to use the ListView view together with Activities and Fragments in Android. The tutorial is based on Eclipse 4.2, Java 1.6 and Android 4.2.
Table of Contents
The display of elements in a lists is a very common pattern in mobile applications. The user sees a list of items and can scroll through them. Such an activity is depicted in the following picture.
Typically the user interacts with the list via the action bar, for example via a refresh button. Individual list item can be selected, this selection can update the action bar or can trigger a detailed screen for the selection. The following graphic sketches that on the selection of a list item another application is started.
Android provides the
ListView or ExpandableListView classes which is capable of displaying a scrollable list of items. ExpandableListView supports also a grouping of items. The items in the list can be of any type.An adapter is used for managing the items in the list (the data model or data source).
An adapters manages the data model and adapts it to the individual rows in the list view. An adapter extend the
BaseAdapter class.Every line in the list view consists of a layout which can be as complex as you want. A typical line in a list view has an image on left side and two text lines in the middle as depicted in the following graphic.
A layout file for a such a line might look like the following.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="?android:attr/listPreferredItemHeight"
android:padding="6dip" >
<ImageView
android:id="@+id/icon"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_alignParentTop="true"
android:layout_marginRight="6dip"
android:contentDescription="TODO"
android:src="@drawable/ic_launcher" />
<TextView
android:id="@+id/secondLine"
android:layout_width="fill_parent"
android:layout_height="26dip"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_toRightOf="@id/icon"
android:ellipsize="marquee"
android:singleLine="true"
android:text="Description"
android:textSize="12sp" />
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_above="@id/secondLine"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_alignWithParentIfMissing="true"
android:layout_toRightOf="@id/icon"
android:gravity="center_vertical"
android:text="Example application"
android:textSize="16sp" />
</RelativeLayout>
The adapter would inflate the layout for each row in its
getView() method and assign the data to the individual views in the row.The adapter is assigned to the
ListView via the setAdapter method on the ListView object.Filtering and sorting of the data is handled by the adapter. You need to implement the logic in your custom adapter implementation.
Android provides default adapter implementations; the most important are
ArrayAdapter andCursorAdapter.ArrayAdapter can handle data based on Arrays or java.util.List.SimpleCursorAdapter can handle database related data.The following listing shows a layout file called
activity_listviewexampleactivity.xml with includes aListView.<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/listview"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
The following example shows the usage of the
ListView view in an activity. It usage a default layout from the Android platform for the row layout. It also demonstrates the removal of list items and uses animations for the removal.package com.vogella.android.listview.withanimation;
public class ListViewExampleActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listviewexampleactivity);
final ListView listview = (ListView) findViewById(R.id.listview);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2", "Ubuntu", "Windows7", "Max OS X", "Linux",
"OS/2", "Ubuntu", "Windows7", "Max OS X", "Linux", "OS/2",
"Android", "iPhone", "WindowsMobile" };
final ArrayList<String> list = new ArrayList<String>();
for (int i = 0; i < values.length; ++i) {
list.add(values[i]);
}
final StableArrayAdapter adapter = new StableArrayAdapter(this,
android.R.layout.simple_list_item_1, list);
listview.setAdapter(adapter);
listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, final View view,
int position, long id) {
final String item = (String) parent.getItemAtPosition(position);
view.animate().setDuration(2000).alpha(0)
.withEndAction(new Runnable() {
@Override
public void run() {
list.remove(item);
adapter.notifyDataSetChanged();
view.setAlpha(1);
}
});
}
});
}
private class StableArrayAdapter extends ArrayAdapter<String> {
HashMap<String, Integer> mIdMap = new HashMap<String, Integer>();
public StableArrayAdapter(Context context, int textViewResourceId,
List<String> objects) {
super(context, textViewResourceId, objects);
for (int i = 0; i < objects.size(); ++i) {
mIdMap.put(objects.get(i), i);
}
}
@Override
public long getItemId(int position) {
String item = getItem(position);
return mIdMap.get(item);
}
@Override
public boolean hasStableIds() {
return true;
}
}
}
To react to selections in the list set an OnItemClickListener to your
ListView.listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(getApplicationContext(),
"Click ListItem Number " + position, Toast.LENGTH_LONG)
.show();
}
});
The
ArrayAdapter class can handle a list or array of Java objects as input. Every Java object is mapped to one row. By default it maps the toString() method of the object to a view in the row layout.You can define the ID of the view in the constructor of the
ArrayAdapter otherwise theandroid.R.id.text1 ID is used as default.The
ArrayAdapter class allows to remove all elements in its underlying data structure with theclear() method call. You can then add new elements via the add() method or a Collection via theaddAll() method.You can also directly modify the underlying data structure and call the
notifyDataSetChanged()method on the adapter to notify him about the changes in data.The
ArrayAdapter is limited as it supports only the mapping of the toString() to one view in the row layout.To control the data assignment and to support several views, you have to create your customer adapter implementation.
For this you would extend an existing adapter implementations or subclass the
BaseAdapter class directly.ListView calls the getView() method on the adapter for each data element. In this method the adapter creates the row layout and maps the data to the views in the layout.This root of the layout is typically a
ViewGroup and contains several other Views, e.g. anImageView and a TextView. The following graphic shows a list with different layouts for odd and even rows.
Within the
getView() method you would inflate an XML based layout and then set the content of the individual views based on the Java object for this row. To inflate the XML layout file you can use the system service LayoutInflator. This service can get accessed via the activity or via thecontext.getSystemService(Context.LAYOUT_INFLATER_SERVICE) method call.The individual elements in the layout can be found via the
findViewById() method call on the top level view.The following code shows an implementation of an custom adapter. This adapter assumes that you have two png files (no.png and yes.png) in one of your
res/drawable folders. The coding inflates an XML layout file, finds the relevant views in the layout and sets their content based on the input data.package de.vogella.android.listactivity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class MySimpleArrayAdapter extends ArrayAdapter<String> {
private final Context context;
private final String[] values;
public MySimpleArrayAdapter(Context context, String[] values) {
super(context, R.layout.rowlayout, values);
this.context = context;
this.values = values;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.rowlayout, parent, false);
TextView textView = (TextView) rowView.findViewById(R.id.label);
ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
textView.setText(values[position]);
// Change the icon for Windows and iPhone
String s = values[position];
if (s.startsWith("iPhone")) {
imageView.setImageResource(R.drawable.no);
} else {
imageView.setImageResource(R.drawable.ok);
}
return rowView;
}
}
An adapter can receive any Java object as input. In its
getView() method it extracts the correct data from the data object and assigns this data to the views in the row which is representing the data.The row can also contain views which interact with the underlying data model via the adapter. For example you can have a
Checkbox in your row layout and if the Checkbox is selected, the underlying data is changed.The
ListActivity class which extends the Activity class and the ListFragment which extends the Fragment class were designed to simplify the handling of ListViews.It you do not have to assign a layout to these elements. If you don not define a layout the activity or fragment contains by default a single
ListView. ListActivity and ListFragment also allow you to override a onListItemClick() method for handling selection of list items.Both classes allow you to set the adapter to the default
ListView via the setListAdapter()method.The following example code shows a simple
ListFragment implementation.package de.vogella.android.fragments;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.app.ListFragment;
public class MyListFragment extends ListFragment {
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_1, values);
setListAdapter(adapter);
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// do something with the data
}
}
The next example code demonstrates the usage of a
ListActivity.package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
public class MyListActivity extends ListActivity {
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, values);
setListAdapter(adapter);
}
}
If you want to use your custom layout with
ListActivity or ListFragment your layout mustcontain a ListView with the android:id attribute set to @android:id/list.<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ListView>
You can also use a view with the
@android:id/empty ID in your layout. The corresponding activity and fragment shows this view automatically if the ListView is empty and hides it otherwise. For example you could display in such a view an error message.By default a
ListView has no selection mode active. You can activate it via the setChoiceMode()method call. Pass ListView.CHOICE_MODE_MULTIPLE for multiple selection orListView.CHOICE_MODE_SINGLE to this method.To get the selected items of a
ListView use the getCheckedItemPosition() for a single selection method or listView.getCheckedItemPositions() for multiple selections. . If you have stable ID you could also use the getCheckedItemIds() method to get the selected IDs.Android provides already a default layout for this, the
android.R.layout.simple_list_item_multiple_choice layout which contains a configured CheckedTextView view.The following activities demonstrates how to use these selection modes. If you use these modes the
ListView stores the selected values, it is not persisted in your data model.package com.vogella.android.listview.selection.multi;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.vogella.android.listview.selection.R;
public class MainActivity extends ListActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String[] values = new String[] { "a", "b", "c", "d", "e", "f", "g",
"h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s",
"t", "u", "w", "x", "y", "z" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_multiple_choice, values);
setListAdapter(adapter);
getListView().setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
Toast.makeText(this,
String.valueOf(getListView().getCheckedItemCount()),
Toast.LENGTH_LONG).show();
return true;
}
}
package com.vogella.android.listview.selection.single;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends ListActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String[] values = new String[] { "a", "b", "c", "d", "e", "f", "g",
"h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s",
"t", "u", "w", "x", "y", "z" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_single_choice, values);
setListAdapter(adapter);
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
Toast.makeText(this,
String.valueOf(getListView().getCheckedItemCount()),
Toast.LENGTH_LONG).show();
return true;
}
}
Every
View which get inflated from an XML layout file will result in a Java object. Creating Java objects is expensive with regards to time and memory consumption.In addition using the
findViewById() method is relatively time consuming, even though it is not as bad as XML inflating.This part describes how to reduce these operations to make your
ListView faster. The default Android adapters like ArrayAdapter are already performance optimized.A
ListView typically contain more data then the number of displayed rows. If the user scrolls the list then rows and their associated Views will be scrolled out of the visible area. The Java objects which represents the rows can be reused for newly visible rows.If Android determines that a
View which represents a row is not visible anymore it allows thegetView() method to reuse it via the convertView parameter.A performance optimized adapter assigns the new data to the
convertView. This avoids inflating an XML file and creating new Java objects.In case no
View is available for reuse, Android will pass null to the convertView parameter. Therefore the adapter implementation need to check for this.The View Holder pattern allows to avoid the
findViewById() method call for a reusedconvertView.A ViewHolder class is a static inner class in your adapter which hold references to the relevant
Viewsin your layout. This reference is assigned to the View which represent the row layout as a tag via thesetTag() method.If we receive a
convertView object, we can get the instance of the ViewHolder via the getTag()method and assign the new attributes to the Views via the ViewHolder reference.While this sounds complex this is approx. 15 % faster then using the
findViewById() method.The following code shows a performance optimized adapter implementation which reuses existing views and implements the holder pattern.
package de.vogella.android.listactivity;
import android.app.Activity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class MyPerformanceArrayAdapter extends ArrayAdapter<String> {
private final Activity context;
private final String[] names;
static class ViewHolder {
public TextView text;
public ImageView image;
}
public MyPerformanceArrayAdapter(Activity context, String[] names) {
super(context, R.layout.rowlayout, names);
this.context = context;
this.names = names;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View rowView = convertView;
if (rowView == null) {
LayoutInflater inflater = context.getLayoutInflater();
rowView = inflater.inflate(R.layout.rowlayout, null);
ViewHolder viewHolder = new ViewHolder();
viewHolder.text = (TextView) rowView.findViewById(R.id.TextView01);
viewHolder.image = (ImageView) rowView
.findViewById(R.id.ImageView01);
rowView.setTag(viewHolder);
}
ViewHolder holder = (ViewHolder) rowView.getTag();
String s = names[position];
holder.text.setText(s);
if (s.startsWith("Windows7") || s.startsWith("iPhone")
|| s.startsWith("Solaris")) {
holder.image.setImageResource(R.drawable.no);
} else {
holder.image.setImageResource(R.drawable.ok);
}
return rowView;
}
}
For following assumes that you already familiar with the concept of the ActionBar and contextual action mode in general. In part will explain how to use contextual action mode for a
ListView selection.To assign a contextual action mode to a long click on a individual item, use the method
setOnItemLongClickListener() on ListView. This methods includes information about the selected item. In this method you can start the ActionMode.The following examples demonstrates that, it assumes that you have a menu XML file defined called "rowselection.xml" and that this menu contains one entry with the "@+id/menuitem1_show" ID.
package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.ActionMode;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Toast;
public class MyListActivityActionbar extends ListActivity {
protected Object mActionMode;
public int selectedItem = -1;
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2", "Ubuntu", "Windows7", "Max OS X", "Linux",
"OS/2", "Ubuntu", "Windows7", "Max OS X", "Linux", "OS/2" };
MySimpleArrayAdapter adapter = new MySimpleArrayAdapter(this, values);
setListAdapter(adapter);
getListView().setOnItemLongClickListener(new OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view,
int position, long id) {
if (mActionMode != null) {
return false;
}
selectedItem = position;
// start the CAB using the ActionMode.Callback defined above
mActionMode = MyListActivityActionbar.this
.startActionMode(mActionModeCallback);
view.setSelected(true);
return true;
}
});
}
private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() {
// called when the action mode is created; startActionMode() was called
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
// Inflate a menu resource providing context menu items
MenuInflater inflater = mode.getMenuInflater();
// assumes that you have "contexual.xml" menu resources
inflater.inflate(R.menu.rowselection, menu);
return true;
}
// the following method is called each time
// the action mode is shown. Always called after
// onCreateActionMode, but
// may be called multiple times if the mode is invalidated.
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return false; // Return false if nothing is done
}
// called when the user selects a contextual menu item
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
switch (item.getItemId()) {
case R.id.menuitem1_show:
show();
// the Action was executed, close the CAB
mode.finish();
return true;
default:
return false;
}
}
// called when the user exits the action mode
public void onDestroyActionMode(ActionMode mode) {
mActionMode = null;
selectedItem = -1;
}
};
private void show() {
Toast.makeText(MyListActivityActionbar.this,
String.valueOf(selectedItem), Toast.LENGTH_LONG).show();
}
}
If you start your application and long press on an item in the list, you get your contextual ActionBarmenu.
It is good practice to allow the user to undo critical actions. Such a critical action is for example the deletion of list items.
A proven pattern to handle this undo option is to offer a selection at the end of the screen. This selection vanishes after a predefined time or once the user continues to interact with the application.
For example the Gmail application implements such a behavior.
The following description contains an example for implementing an undo action. Is uses an animation to phase out the undo button automatically out after a while.
Create for this example a new project called com.vogella.android.userinterface.undo based on theBlankTemplate template.
Create the following layout for your activity. It uses a
FrameLayout to show two different parts of the user interface. The button bar is initial hidden. The button uses a drawable, either add such a drawable to your project or remove the reference.<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<ListView
android:id="@+id/listview"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</ListView>
</RelativeLayout>
<LinearLayout
android:id="@+id/undobar"
android:visibility="gone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|center_horizontal"
android:layout_margin="20dp"
android:alpha="100"
android:background="#808080"
android:dividerPadding="11dp"
android:padding="4dp" >
<TextView
android:id="@+id/undobar_message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Deleted"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textColor="#fff" />
<Button
android:id="@+id/undobar_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="30dp"
android:onClick="onClick"
android:background="#808080"
android:drawableLeft="@drawable/ic_undobar_undo"
android:text="Undo"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textColor="#fff" />
</LinearLayout>
</FrameLayout>
Change your activity so that it is similar to the following code. The Android project wizard in Eclipse generated already an ActionBar entry, this entry is used in the following code. If in doubt create your own ActionBar entry.
package com.vogella.android.userinterface.undo;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.vogella.android.actionbar.undo.R;
public class MainActivity extends Activity {
private View viewContainer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListView l = (ListView) findViewById(R.id.listview);
String[] values = new String[] { "Ubuntu", "Android", "iPhone",
"Windows", "Ubuntu", "Android", "iPhone", "Windows" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, values);
viewContainer = findViewById(R.id.undobar);
l.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
showUndo(viewContainer);
return true;
}
public void onClick(View view) {
Toast.makeText(this, "Deletion undone", Toast.LENGTH_LONG).show();
viewContainer.setVisibility(View.GONE);
}
public static void showUndo(final View viewContainer) {
viewContainer.setVisibility(View.VISIBLE);
viewContainer.setAlpha(1);
viewContainer.animate().alpha(0.4f).setDuration(5000)
.withEndAction(new Runnable() {
@Override
public void run() {
viewContainer.setVisibility(View.GONE);
}
});
}
}
If you select the entry in the ActionBar the button bar becomes visible for 5 seconds.
The following exercise demonstrates how to use a
ListView in an ListActivity. You use the predefined ArrayAdapter class and an existing Android layout for the rows.Create a new Android project called de.vogella.android.listactivity with the activity called
MyListActivity.Change
MyListActivity to the following. Note that the setContentView() method is not used.package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class MyListActivity extends ListActivity {
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, values);
setListAdapter(adapter);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
String item = (String) getListAdapter().getItem(position);
Toast.makeText(this, item + " selected", Toast.LENGTH_LONG).show();
}
}
In our example your will define your layout for the rows and use it in your adapter.
Create the "rowlayout.xml" layout file in the
res/layout folder of the "de.vogella.android.listactivity" project.<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<ImageView
android:id="@+id/icon"
android:layout_width="22px"
android:layout_height="22px"
android:layout_marginLeft="4px"
android:layout_marginRight="10px"
android:layout_marginTop="4px"
android:src="@drawable/ic_launcher" >
</ImageView>
<TextView
android:id="@+id/label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@+id/label"
android:textSize="20px" >
</TextView>
</LinearLayout>
Change your activity so that is using the new layout. You use a different constructor to identify the
Viewto which the ArrayAdapter assigns the text. If this ID is not provides Android searches for an element with the @android:id/text1 ID in the layout of the row.package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class MyListActivity extends ListActivity {
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2" };
// use your own layout
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
R.layout.rowlayout, R.id.label, values);
setListAdapter(adapter);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
String item = (String) getListAdapter().getItem(position);
Toast.makeText(this, item + " selected", Toast.LENGTH_LONG).show();
}
}
The following uses two images "no.png" and "ok.png". I placed it in the "res/drawable-mdpi" folder. You must create your own icons. In case you do not find any icons just copy "icon.png" and use a drawing program to change it a little bit.
Create the class
MySimpleArrayAdapter which will serve as our adapter.package de.vogella.android.listactivity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class MySimpleArrayAdapter extends ArrayAdapter<String> {
private final Context context;
private final String[] values;
public MySimpleArrayAdapter(Context context, String[] values) {
super(context, R.layout.rowlayout, values);
this.context = context;
this.values = values;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.rowlayout, parent, false);
TextView textView = (TextView) rowView.findViewById(R.id.label);
ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
textView.setText(values[position]);
// Change the icon for Windows and iPhone
String s = values[position];
if (s.startsWith("Windows7") || s.startsWith("iPhone")
|| s.startsWith("Solaris")) {
imageView.setImageResource(R.drawable.no);
} else {
imageView.setImageResource(R.drawable.ok);
}
return rowView;
}
}
To use this adapter, change the activity to the following.
package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
public class MyListActivity extends ListActivity {
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2" };
MySimpleArrayAdapter adapter = new MySimpleArrayAdapter(this, values);
setListAdapter(adapter);
}
}
If you run this example you should get a list with different icons for the certain elements.
The following will implement a performance optimized version of the adapter from the previous example.
Create the following
MyPerformanceArrayAdapter class.package de.vogella.android.listactivity;
import android.app.Activity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class MyPerformanceArrayAdapter extends ArrayAdapter<String> {
private final Activity context;
private final String[] names;
static class ViewHolder {
public TextView text;
public ImageView image;
}
public MyPerformanceArrayAdapter(Activity context, String[] names) {
super(context, R.layout.rowlayout, names);
this.context = context;
this.names = names;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View rowView = convertView;
if (rowView == null) {
LayoutInflater inflater = context.getLayoutInflater();
rowView = inflater.inflate(R.layout.rowlayout, null);
ViewHolder viewHolder = new ViewHolder();
viewHolder.text = (TextView) rowView.findViewById(R.id.TextView01);
viewHolder.image = (ImageView) rowView
.findViewById(R.id.ImageView01);
rowView.setTag(viewHolder);
}
ViewHolder holder = (ViewHolder) rowView.getTag();
String s = names[position];
holder.text.setText(s);
if (s.startsWith("Windows7") || s.startsWith("iPhone")
|| s.startsWith("Solaris")) {
holder.image.setImageResource(R.drawable.no);
} else {
holder.image.setImageResource(R.drawable.ok);
}
return rowView;
}
}
Use your new adapter in your activity. If you run the application it should look the same but it will be much faster, especially for large datasets.
package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
public class MyListActivity extends ListActivity {
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2" };
setListAdapter(new MyPerformanceArrayAdapter(this, values));
}
}
You can use the
SimpleAdapter class to show the data of two elements. This class expects a Array of Strings (from data) in which the fields of the input data are defined. It also requires a Array of ints which defines the IDs of the widgets in the layout for the row to which these fields are mapped.The actual data is then a list of Maps. The Map defines for each field in the from data a value.
The following shows an example which reuses an predefined layout from Android for the row.
package de.vogella.android.listactivity;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import android.app.ListActivity;
import android.os.Bundle;
import android.widget.SimpleAdapter;
public class MyTwoListItemsActivity extends ListActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ArrayList<Map<String, String>> list = buildData();
String[] from = { "name", "purpose" };
int[] to = { android.R.id.text1, android.R.id.text2 };
SimpleAdapter adapter = new SimpleAdapter(this, list,
android.R.layout.simple_list_item_2, from, to);
setListAdapter(adapter);
}
private ArrayList<Map<String, String>> buildData() {
ArrayList<Map<String, String>> list = new ArrayList<Map<String, String>>();
list.add(putData("Android", "Mobile"));
list.add(putData("Windows7", "Windows7"));
list.add(putData("iPhone", "iPhone"));
return list;
}
private HashMap<String, String> putData(String name, String purpose) {
HashMap<String, String> item = new HashMap<String, String>();
item.put("name", name);
item.put("purpose", purpose);
return item;
}
}
Frequently you need to select items in your
ListView. As the row of the ListView are getting recycled you cannot store the selection on the View level.
Selection is just one possible example but you can imange other interaction between your row and model.
To persist the selection you have to update your data model with the selected state.
To update the data model in your
ListView you define your own Adapter class. In this adapter class you attach a listener to the View which is responsible for selecting the model element. If selected you update the state in the model which you can add as a tag to the View to have access to it.The following example demonstrates how to use standard Java object and how to interact from the
Views with the model.Continue to use the
de.vogella.android.listactivity project.Create the following
Model which hold the name and the information if this element is currently selected.package de.vogella.android.listactivity;
public class Model {
private String name;
private boolean selected;
public Model(String name) {
this.name = name;
selected = false;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public boolean isSelected() {
return selected;
}
public void setSelected(boolean selected) {
this.selected = selected;
}
}
Create the following new layout file called
rowbuttonlayout.xml.<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@+id/label"
android:textSize="30px" >
</TextView>
<CheckBox
android:id="@+id/check"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_marginLeft="4px"
android:layout_marginRight="10px" >
</CheckBox>
</RelativeLayout>
Create the following
Adapter. This adapter adds a listener on the Checkbox view . If the checkbox is selected the underlying data of the model is changed. Checkbox gets the corresponding model element assigned via the getTag() method.package de.vogella.android.listactivity;
import java.util.List;
import android.app.Activity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;
public class InteractiveArrayAdapter extends ArrayAdapter<Model> {
private final List<Model> list;
private final Activity context;
public InteractiveArrayAdapter(Activity context, List<Model> list) {
super(context, R.layout.rowbuttonlayout, list);
this.context = context;
this.list = list;
}
static class ViewHolder {
protected TextView text;
protected CheckBox checkbox;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = null;
if (convertView == null) {
LayoutInflater inflator = context.getLayoutInflater();
view = inflator.inflate(R.layout.rowbuttonlayout, null);
final ViewHolder viewHolder = new ViewHolder();
viewHolder.text = (TextView) view.findViewById(R.id.label);
viewHolder.checkbox = (CheckBox) view.findViewById(R.id.check);
viewHolder.checkbox
.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
Model element = (Model) viewHolder.checkbox
.getTag();
element.setSelected(buttonView.isChecked());
}
});
view.setTag(viewHolder);
viewHolder.checkbox.setTag(list.get(position));
} else {
view = convertView;
((ViewHolder) view.getTag()).checkbox.setTag(list.get(position));
}
ViewHolder holder = (ViewHolder) view.getTag();
holder.text.setText(list.get(position).getName());
holder.checkbox.setChecked(list.get(position).isSelected());
return view;
}
}
Finally change your activity to the following.
package de.vogella.android.listactivity;
import java.util.ArrayList;
import java.util.List;
import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
public class MyList extends ListActivity {
/** Called when the activity is first created. */
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// create an array of Strings, that will be put to our ListActivity
ArrayAdapter<Model> adapter = new InteractiveArrayAdapter(this,
getModel());
setListAdapter(adapter);
}
private List<Model> getModel() {
List<Model> list = new ArrayList<Model>();
list.add(get("Linux"));
list.add(get("Windows7"));
list.add(get("Suse"));
list.add(get("Eclipse"));
list.add(get("Ubuntu"));
list.add(get("Solaris"));
list.add(get("Android"));
list.add(get("iPhone"));
// Initially select one of the items
list.get(1).setSelected(true);
return list;
}
private Model get(String s) {
return new Model(s);
}
}
If you start your app you should be able to flag items. These changes will be reflected in your model.
The
ExpandableListView is similar to ListView but allow you to define groups and details for this group. ExpandableListView expects and adapter of type BaseExpandableListAdapter.In this case you have to define two layouts, one for the group and another one for the details row.
In the following example you create an expandable listview similar to the following screenshot.
Create a project called com.vogella.android.listview.expandable with the activity called
MainActivity.Create or adjust the following layout files. First
layout/activity_main.xml.<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<ExpandableListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ExpandableListView>
</LinearLayout>
Afterwards create
layout/listrow_group.xml.<CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="?android:attr/listPreferredItemHeight"
android:layout_marginLeft="8dp"
android:drawableRight="@drawable/ic_launcher"
android:gravity="left"
android:paddingLeft="32dp"
android:paddingTop="8dp"
android:text="Test"
android:textSize="14sp"
android:textAlignment="textEnd"
android:textStyle="bold" />
The last required layout is
layout/listrow_details.xml.<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="40dp"
android:clickable="true"
android:orientation="vertical"
android:paddingLeft="40dp"
tools:context=".MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:drawableLeft="@drawable/ic_launcher"
android:drawablePadding="5dp"
android:gravity="center_vertical"
android:text="@string/hello_world"
android:textSize="14sp"
android:textStyle="bold" >
</TextView>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />
</LinearLayout>
Create the following class which hold your domain model for the
ExpandableListView.package com.vogella.android.listview.expandable;
import java.util.ArrayList;
import java.util.List;
public class Group {
public String string;
public final List<String> children = new ArrayList<String>();
public Group(String string) {
this.string = string;
}
}
Finally create the adapter as described by the following listing and change the activity to the code provided below.
package com.vogella.android.listview.expandable;
import android.app.Activity;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.CheckedTextView;
import android.widget.TextView;
import android.widget.Toast;
public class MyExpandableListAdapter extends BaseExpandableListAdapter {
private final SparseArray<Group> groups;
public LayoutInflater inflater;
public Activity activity;
public MyExpandableListAdapter(Activity act, SparseArray<Group> groups) {
activity = act;
this.groups = groups;
inflater = act.getLayoutInflater();
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return groups.get(groupPosition).children.get(childPosition);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return 0;
}
@Override
public View getChildView(int groupPosition, final int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
final String children = (String) getChild(groupPosition, childPosition);
TextView text = null;
if (convertView == null) {
convertView = inflater.inflate(R.layout.listrow_details, null);
}
text = (TextView) convertView.findViewById(R.id.textView1);
text.setText(children);
convertView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(activity, children,
Toast.LENGTH_SHORT).show();
}
});
return convertView;
}
@Override
public int getChildrenCount(int groupPosition) {
return groups.get(groupPosition).children.size();
}
@Override
public Object getGroup(int groupPosition) {
return groups.get(groupPosition);
}
@Override
public int getGroupCount() {
return groups.size();
}
@Override
public void onGroupCollapsed(int groupPosition) {
super.onGroupCollapsed(groupPosition);
}
@Override
public void onGroupExpanded(int groupPosition) {
super.onGroupExpanded(groupPosition);
}
@Override
public long getGroupId(int groupPosition) {
return 0;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = inflater.inflate(R.layout.listrow_group, null);
}
Group group = (Group) getGroup(groupPosition);
((CheckedTextView) convertView).setText(group.string);
((CheckedTextView) convertView).setChecked(isExpanded);
return convertView;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return false;
}
}
package com.vogella.android.listview.expandable;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.Menu;
import android.widget.ExpandableListView;
public class MainActivity extends Activity {
// more efficient than HashMap for mapping integers to objects
SparseArray<Group> groups = new SparseArray<Group>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
createData();
ExpandableListView listView = (ExpandableListView) findViewById(R.id.listView);
MyExpandableListAdapter adapter = new MyExpandableListAdapter(this,
groups);
listView.setAdapter(adapter);
}
public void createData() {
for (int j = 0; j < 5; j++) {
Group group = new Group("Test " + j);
for (int i = 0; i < 5; i++) {
group.children.add("Sub Item" + i);
}
groups.append(j, group);
}
}
}
You can also add a
LongItemClickListener to the View. For this receive the ListView via thegetListVIew() method and set the LongItemClickListener via the setOnItemLongClickListener() method.package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class MyList extends ListActivity {
/** Called when the activity is first created. */
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// create an array of Strings, that will be put to our ListActivity
String[] names = new String[] { "Linux", "Windows7", "Eclipse", "Suse",
"Ubuntu", "Solaris", "Android", "iPhone" };
ArrayAdapter<String> adapter = new MyPerformanceArrayAdapter(this, names);
setListAdapter(adapter);
ListView list = getListView();
list.setOnItemLongClickListener(new OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(MyList.this,
"Item in position " + position + " clicked",
Toast.LENGTH_LONG).show();
// Return true to consume the click event. In this case the
// onListItemClick listener is not called anymore.
return true;
}
});
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
// Get the item that was clicked
Object o = this.getListAdapter().getItem(position);
String keyword = o.toString();
Toast.makeText(this, "You selected: " + keyword, Toast.LENGTH_SHORT)
.show();
}
}
You can of course put arbitrary
Views elements around your ListView. For example you can define a layout with two TextViews and a ListView between them. In this case the two TextViews will always be visible above the List (header) and the other will be visible below the ListView. If you want to display a list header or list footer only at the see the beginning or end of the list you can use thesetHeaderView() method or setFooterView() method on ListView.package de.vogella.android.listactivity;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class MyList extends ListActivity {
/** Called when the activity is first created. */
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// create an array of Strings, that will be put to our ListActivity
String[] names = new String[] { "Linux", "Windows7", "Eclipse", "Suse",
"Ubuntu", "Solaris", "Android", "iPhone", "Linux", "Windows7",
"Eclipse", "Suse", "Ubuntu", "Solaris", "Android", "iPhone" };
View header = getLayoutInflater().inflate(R.layout.header, null);
View footer = getLayoutInflater().inflate(R.layout.footer, null);
ListView listView = getListView();
listView.addHeaderView(header);
listView.addFooterView(footer);
setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_single_choice,
android.R.id.text1, names));
}
}
In case you work with a content provider or directly with the database you can use the
SimpleCursorAdapter to define the data for your ListView. The following will demonstrates how to access the Contacts ContentProvider.Create a new Android project called "de.vogella.android.listactivity.cursor" with the activity calledMyListActivity. Change
MyListActivity to the following.package de.vogella.android.listactivity.cursor;
import android.app.ListActivity;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.widget.ListAdapter;
import android.widget.SimpleCursorAdapter;
public class MyListActivity extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Cursor mCursor = getContacts();
startManagingCursor(mCursor);
// now create a new list adapter bound to the cursor.
// SimpleListAdapter is designed for binding to a Cursor.
ListAdapter adapter = new SimpleCursorAdapter(this, // Context.
android.R.layout.two_line_list_item, // Specify the row template
// to use (here, two
// columns bound to the
// two retrieved cursor
// rows).
mCursor, // Pass in the cursor to bind to.
// Array of cursor columns to bind to.
new String[] { ContactsContract.Contacts._ID,
ContactsContract.Contacts.DISPLAY_NAME },
// Parallel array of which template objects to bind to those
// columns.
new int[] { android.R.id.text1, android.R.id.text2 });
// Bind to our new adapter.
setListAdapter(adapter);
}
private Cursor getContacts() {
// Run query
Uri uri = ContactsContract.Contacts.CONTENT_URI;
String[] projection = new String[] { ContactsContract.Contacts._ID,
ContactsContract.Contacts.DISPLAY_NAME };
String selection = ContactsContract.Contacts.IN_VISIBLE_GROUP + " = '"
+ ("1") + "'";
String[] selectionArgs = null;
String sortOrder = ContactsContract.Contacts.DISPLAY_NAME
+ " COLLATE LOCALIZED ASC";
return managedQuery(uri, projection, selection, selectionArgs,
sortOrder);
}
}
Make sure you give your application the permission to read the contacts. (Uses Permissions "android.permission.READ_CONTACTS" in AndroidManifest.xml)
Sometimes having to press a refresh button on the ActionBar to refresh data can be annoying for the user. Chris Banes has implemented an Open Source library to implement the pull to refresh pattern for a
Listview. https://github.com/chrisbanes/Android-PullToRefresh.Also you may want to use the swipe to dismiss gesture to delete items from a ListView. Roman Nurik provides an example for this at Android swipe-to-dismiss library which Jake Wharton backported to earlier Android releases at SwipeToDismissNOA .
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