I've implemented a custom view with hosts two subviews which are identified by an id in the xml. When using two of this custom view in the same layout I run into the problem that it is random which custom view is chosen.
How can I write a custom view with different view ids that can be multiply used in the same layout?
Here is the xml of the custom view:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<EditText
android:id="@+id/clearable_edit"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:inputType="textCapWords"
android:paddingRight="35dip" />
<Button
android:id="@+id/clearable_button_clear"
android:layout_width="30dip"
android:layout_height="30dip"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="5dip"
android:background="@drawable/clear_button" />
</RelativeLayout>
The id (android:id="@+id/clearable_edit") of the EditText is the problem here.
Usage of custom view:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<com.custom.package.ClearableEditText
android:id="@+id/arr_location"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
</com.custom.package.ClearableEditText>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<com.custom.package.ClearableEditText
android:id="@+id/dep_location"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
</com.custom.package.ClearableEditText>
</LinearLayout>
In this example the views of type "ClearableEditText" share the same id of their EditText subview.
Here is the code for ClearableEditText:
public class ClearableEditText extends RelativeLayout {
private LayoutInflater inflater = null;
private EditText edit_text;
private Button btn_clear;
public ClearableEditText(Context context, AttributeSet attrs, int defStyle){
super(context, attrs, defStyle);
initViews();
}
public ClearableEditText(Context context, AttributeSet attrs){
super(context, attrs);
initViews();
}
public ClearableEditText(Context context){
super(context);
initViews();
}
private void initViews(){
inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.clearable_edittext, this, true);
edit_text = (EditText) view.findViewById(R.id.clearable_edit);
btn_clear = (Button) findViewById(R.id.clearable_button_clear);
btn_clear.setVisibility(RelativeLayout.INVISIBLE);
}
}
A ViewGroup is a special view that can contain other views (called children.)
Custom Views is just a way to make an android developer a painter. When you need to create some custom and reuse the views when it is not provided by the Android Ecosystem. Custom Views can be used as widgets like TextView, EditText etc.
No, not every view needs an id. You add ids to views when you need to modify properties of that views and you find those views with their ids.
A well-designed custom view is much like any other well-designed class. It encapsulates a specific set of functionality with an easy to use interface, it uses CPU and memory efficiently, and so on. In addition to being a well-designed class, though, a custom view should: Conform to Android standards.
First fetch parent View
like this:
View v1 = findViewById(R.id.arr_location);
and then
EditText ed1 = (EditText)v1.findViewById(R.id.clearable_edit);
Similarly
View v2 = findViewById(R.id.dep_location);
EditText ed2 = (EditText)v2.findViewById(R.id.clearable_edit);
This way you can add as many ClearableEditText
as you want having same id for EditText
and Button
. Just make sure that every ClearableEditText
has different id e.g. in this case R.id.arr_location
and R.id.dep_location
.
I've found a solution.
I've added a method to ClearableEditText where you can set the id of the underlying EditText from outside the object and set it with a new id.
Here is a code sample:
//inside ClearableEditText
public void setEditId(int id){
edit_text.setId(id);
}
//somewhere else
departureLocation = (ClearableEditText)view.findViewById(R.id.dep_location);
departureLocation.setEditId(R.id.clearable1);
arrivalLocation = (ClearableEditText)view.findViewById(R.id.arr_location);
arrivalLocation.setEditId(R.id.clearable2);
The Ids are created with a "ids.xml" in the values folder, which causes eclipse/ADT to create a placeholder id for the entered items
<?xml version="1.0" encoding="utf-8"?>
<resources>
<!-- This file is used to create unique ids for custom views, which will be used more
than once in the same layout file. Using unique ids prevents the custom view from getting
the wrong state. -->
<item name="clearable1" type="id"></item>
<item name="clearable2" type="id"></item>
</resources>
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