How to declare several stylable attributes with the same name for different tags?

Question

I want both my ViewA and ViewB to have the "title" tag. But I can't put this in attrs.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="ViewA">
        <attr name="title" format="string" />
    </declare-styleable>
    <declare-styleable name="ViewB">
        <attr name="title" format="string" />
        <attr name="max" format="integer" />
    </declare-styleable>
</resources>

because of the error Attribute "title" has already been defined. Another question shows this solution:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="title" format="string" />
    <declare-styleable name="ViewB">
        <attr name="max" format="integer" />
    </declare-styleable>
</resources>

but in that case, R.styleable.ViewA_title and R.styleable.ViewB_title are not generated. I need them for reading the attributes from the AttributeSet using the following code:

TypedArray a=getContext().obtainStyledAttributes( as, R.styleable.ViewA);
String title = a.getString(R.styleable.ViewA_title);

How can I solve this?

Answer 1

The link you have posted does give you the correct answer. This is what it suggests you do:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="title" format="string" />
    <declare-styleable name="ViewA">
        <attr name="title" />
    </declare-styleable>
    <declare-styleable name="ViewB">
        <attr name="title" />
        <attr name="max" format="integer" />
    </declare-styleable>
</resources>

Now, R.styleable.ViewA_titleand R.styleable.ViewB_titleare both accessible.

If you get a chance, read through this answer: Link. Relevant quote:

You can define attributes in the top element or inside of a element. If I'm going to use an attr in more than one place I put it in the root element.

Answer 2

Do this instead. No parent tag needed

<resources>
    <declare-styleable name="ViewA">
        <attr name="title" format="string" />
    </declare-styleable>

    <declare-styleable name="ViewB" >
        <attr name="title" /> 
        <attr name="min" format="integer" />
        <attr name="max" format="integer" />
    </declare-styleable>
</resources>

This is because once title is declared in ViewA, it doesn't need (and also can't) to be declared in again in another declare-styleable

Answer 3

<resources>
<declare-styleable name="ViewA">
    <attr name="title" format="string" />
</declare-styleable>

<declare-styleable name="ViewB" parent="ViewA"> // inherit from ViewA
    <attr name="min" format="integer" />
    <attr name="max" format="integer" />
</declare-styleable>

This doesn't work。

<resources>
<attr name="title" format="string" />
<declare-styleable name="ViewA">
    <attr name="title" />
</declare-styleable>
<declare-styleable name="ViewB">
    <attr name="title" />
    <attr name="max" format="integer" />
</declare-styleable>

This also doesn't work。

<resources>
<declare-styleable name="ViewA">
    <attr name="title" format="string" />
</declare-styleable>

<declare-styleable name="ViewB" >
    <attr name="title" /> 
    <attr name="min" format="integer" />
    <attr name="max" format="integer" />
</declare-styleable>

This was OK!!

Answer 4

You need to use inheritance

<resources>
    <declare-styleable name="ViewA">
        <attr name="title" format="string" />
    </declare-styleable>

    <declare-styleable name="ViewB" parent="ViewA"> // inherit from ViewA
        <attr name="min" format="integer" />
        <attr name="max" format="integer" />
    </declare-styleable>
</resources>

In your java code

String namespace = "http://schemas.android.com/apk/res/" + getContext().getPackageName();
int title_resource = attrs.getAttributeResourceValue(namespace, "title", 0); 
String title = "";
if(title_resource!=0){
  title = getContext().getString(title_resource);
}

int min = attrs.getAttributeResourceValue(namespace, "min", 0); // read int value
int max = attrs.getAttributeResourceValue(namespace, "max", 0);