Selection Controls 2 The spinner Control

The spinner controls is similar to the ComboBox in C#. it displays a list to select from in a popup window so ot may become a better choice over ListView if you want to save space.

It works in a similar way to that of the the listView

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
 android_orientation="vertical"
 android_layout_width="fill_parent"
 android_layout_height="fill_parent"
 >
 <Spinner
 android_layout_width="fill_parent" 
 android_layout_height="wrap_content"
 android_id="@+id/Spinner"
 />
</LinearLayout>

when you click on the spinner it popups like this:

To handle the selected item you can use do it like this:

final String [] items=new String[]{"Item1","Item2","Item3","Item4"};
 ArrayAdapter ad=new ArrayAdapter(this,android.R.layout.simple_spinner_item,items);
 ad.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
 Spinner spin=(Spinner)findViewById(R.id.Spinner);
 spin.setAdapter(ad);
 spin.setOnItemSelectedListener(new OnItemSelectedListener()
 {

 public void onItemSelected(AdapterView arg0, View arg1,
 int arg2, long arg3) {
 TextView txt=(TextView)findViewById(R.id.txt);
 TextView temp=(TextView)arg1;
 txt.setText(temp.getText());
 
 }

 public void onNothingSelected(AdapterView arg0) {
 // TODO Auto-generated method stub
 
 }
 
 });

The above code displays the selected item text in the textview.

The parameters of the OnItemClick method are:


• Arg0:the Spinner, notice that it is of type AdapterView.

• Arg1: the view that represents the selected item, in this example it will be a TextView

• Arg2: the position of the selected item.

• Arg3: the id of the selected item.

and thats it for the Spinner Control.

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Selection Controls 3 CheckBox and RadioButton

CheckBox:

The check box has two states: Checked and UnChecked. It inherits from TextView so it has all of its properties:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
 android_orientation="vertical"
 android_layout_width="fill_parent"
 android_layout_height="fill_parent"
 >
 <TextView
 android_layout_width="fill_parent" 
 android_layout_height="wrap_content"
 android_id="@+id/txt"
 />
 <CheckBox
 android_layout_width="fill_parent" 
 android_layout_height="wrap_content"
 android_id="@+id/Chk"
 android_text="This is a check box"
 android_checked="false"
 
 />
</LinearLayout>

and to handle the check/uncheck event:

CheckBox chk=(CheckBox)findViewById(R.id.Chk);
 chk.setOnCheckedChangeListener(new OnCheckedChangeListener()
 {

 public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
 TextView txt=(TextView)findViewById(R.id.txt);
 if (arg1)
 txt.setText("checked");
 else
 txt.setText("Unchecked");
 
 }
 
 }
 );

RadioButton:
Android provides Radio button control. You create a RadioGroup and add RadioButtons inside it.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
 android_orientation="vertical"
 android_layout_width="fill_parent"
 android_layout_height="fill_parent"
 >
 <TextView
 android_id="@+id/txt"
 android_layout_width="fill_parent"
android:layout_height="fill_parent"
 />
 <RadioGroup
 android_id="@+id/group"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="Radio Group"
>
<RadioButton android_id="@+id/item1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Item1"
android:checked="true"
 />
<RadioButton android_id="@+id/item2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Item2" />
<RadioButton android_id="@+id/item3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Item3" />
</RadioGroup>
</LinearLayout>

You can get the checked item from code like this:

RadioGroup rg=(RadioGroup)findViewById(R.id.group);
 rg.setOnCheckedChangeListener(new android.widget.RadioGroup.OnCheckedChangeListener()
 {

 public void onCheckedChanged(RadioGroup arg0, int arg1) {
 // TODO Auto-generated method stub
 TextView txt=(TextView)findViewById(R.id.txt);
 RadioButton rb=(RadioButton)findViewById(arg1);
 txt.setText("You selected "+rb.getText());
 
 }
 
 }
 );

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