Hello
every one, in this post i would like to share about the most powerful view in
our android that is
ListView (i felt this view is the most effective one in Android). ListView class which is capable of displaying a scrollable list of items. The items can be of any type.
We have
lots of ways to set values into a ListView. Some ways that i learned are
- Setting ListView with layout(view) provided by Android resources.
- Setting ListView with our own layout.
- Setting ListView with different images as item.
Now i am
gonna explain each way one by one..
Setting ListView
with layout provided by Android resources
Add Listview
to main.xml
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ListView>
</LinearLayout>
Then
create an array named 'values' in the corresponding acitvity and put some items
in it. Create Listview object and initialize it with corresponding id. Then
comes the magic thing ‘ArrayAdapter’
As we
know Listview is a group of items, each item will contain a TextView. Now the
job of ArrayAdapter is to take each
values from the array ‘values’ and sets the TextView with that value, then this
TextView is set as an item for ListView. So the ArrayAdapter works or loops as
the length of the array we used. On the initialization of ArrayAdapter what we
want to do is, indicate which array we are using and which TextView (or view) we want to use as
item of ListView.
ListExample Activity
for main.xml
public class ListExample extends Activity {
ListView
lv;
String[]
values;
ArrayAdapter<String>myAdapter;
/**
Called when the activity is first created. */
@Override
public void onCreate(Bundle
savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
lv.setAdapter(myAdapter);
}
public void init() {
// TODO Auto-generated
method stub
lv=(ListView)findViewById(R.id.listView1);
values=new String[]{"folder1","image1.png","text.txt","image2.png","folder2","text2.txt"};
myAdapter=new
ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, values);
}
}
Here we have used android.R.layout.simple_list_item_1.
The simple_list_item_1 will
contain a TextView. To see the content in simple_list_item_1 navigate to
android-sdk-windows/platforms/android-(api level)/data/res/layout. Here we see
a lots of xml file which provided by Android resources
simple_list_item_1.xml
<?xml version="1.0"
encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/text1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:gravity="center_vertical"
android:paddingLeft="6dip"
android:minHeight="?android:attr/listPreferredItemHeight"
/>
The
output for the above code will be like this
That's all for this post. The next post will explain 'Setting Listview with our own layout'.
