Review Hướng Dẫn Simple ListView in Android Chi Tiết
We will learn how to create a simple Android ListView and launch a new activity on selecting a single list item.
Nội dung chính
- What is Android ListView?
- Using an Adapter
- Handling Android ListView Clicks
- Android ListView Example Project Structure
- Video tương quan
What is Android ListView?
Android ListView is a view which groups several items and display them in vertical scrollable list. The list items are automatically inserted to the list using an Adapter that pulls content from a source such as an array or database. Its one of the basic and most used UI components of android. The most common usages include displaying data in the form of a vertical scrolling list.
Using an Adapter
An adapter actually bridges between UI components and the data source that fill data into UI Component. Adapter holds the data and send the data to adapter view, the view can take the data from adapter view and shows the data on different views like as spinner, list view, grid view etc. The adapter pulls the items out of a data source, an array for example, and then converts each item into a view which it then inserts into the ListView.
The ListView and GridView are subclasses of AdapterView and they can be populated by binding them to an Adapter, which retrieves data from an external source and creates a View that represents each data entry. The common adapters are ArrayAdapter, BaseAdapter, CursorAdapter, SimpleCursorAdapter, SpinnerAdapter and WrapperListAdapter.
Handling Android ListView Clicks
The onListItemClick() method is used to process the clicks on android ListView item. This method receives 4 parameters:
Android ListView Example Project Structure
Lets begin with defining the string resources file to store all list item labels. So we create an XML file under values thư mục and name it as strings.xml and paste the following code.
strings.xml
<?xml version=”1.0″ encoding=”utf-8″?>
<resourcesvàgt;
<string-array name=”teams”>
<itemvàgt;Indiavàlt;/itemvàgt;
<itemvàgt;South Africavàlt;/itemvàgt;
<itemvàgt;Australiavàlt;/itemvàgt;
<itemvàgt;Englandvàlt;/itemvàgt;
<itemvàgt;New Zealandvàlt;/itemvàgt;
<itemvàgt;Sri Lankavàlt;/itemvàgt;
<itemvàgt;Pakistanvàlt;/itemvàgt;
<itemvàgt;West Indiesvàlt;/itemvàgt;
<itemvàgt;Bangladeshvàlt;/itemvàgt;
<itemvàgt;Irelandvàlt;/itemvàgt;
</string-arrayvàgt;
</resourcesvàgt;
Each list view item will be represented by an xml layout,so lets define the xml layout comprising of a single textview as follows:
list_item.xml
<?xml version=”1.0″ encoding=”utf-8″?>
<!– Single List Item Design –>
<TextView xmlns:android=”https://schemas.android.com/apk/res/android”
android:id=”@+id/textview”
android:layout_width=”fill_parent”
android:layout_height=”fill_parent”
android:padding=”10dip”
android:textSize=”16dip”
android:textStyle=”bold” >
</TextViewvàgt;
Following snippet shows how to import the xml resources data and store them in data followed by binding them to the adapter:
// storing string resources into Array
String[] teams = getResources().getStringArray(R.array.teams);
// Binding resources Array to ListAdapter
this.setListAdapter(new ArrayAdaptervàlt;Stringvàgt;(this, R.layout.list_item, R.id.textview, teams));
In the following code we fetch the data value from the selected item and pass it as a bundle to the next activity using intents.
MainActivity.java
package journaldev.com.listview;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class MainActivity extends ListActivity
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
// storing string resources into Array
String[] teams = getResources().getStringArray(R.array.teams);
// Binding resources Array to ListAdapter
this.setListAdapter(new ArrayAdaptervàlt;Stringvàgt;(this, R.layout.list_item, R.id.textview, teams));
ListView lv = getListView();
// listening to single list item on click
lv.setOnItemClickListener(new AdapterView.OnItemClickListener()
public void onItemClick(AdapterViewvàlt;?> parent, View view,
int position, long id)
// selected item
String team = ((TextView) view).getText().toString();
// Launching new Activity on selecting single List Item
Intent i = new Intent(getApplicationContext(), SecondActivity.class);
// sending data to new activity
i.putExtra(“team”, team);
startActivity(i);
);
The SecondActivity class retrieves the text label from the list item selected and displays it in a textview as shown in the following snippet.
SecondActivity.java
package journaldev.com.listview;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class SecondActivity extends Activity
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
TextView txtProduct = (TextView) findViewById(R.id.team_label);
Intent i = getIntent();
// getting attached intent data
String product = i.getStringExtra(“team”);
// displaying selected product name
txtProduct.setText(product);
Following small GIF depict the flow of the app:
Thats all for a quick android listview example. You should also learn about Expandable ListView. You can tải về android list view project from below link.
Download Android ListView Example Project
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