Question

I have added an easy compound control which loads its layout from a XML layout and implements own XML attributes.

But this only works while this control is in the main package (com.myapp). When I try to move it into a subpackage like com.myapp.controls things begin to fail.

This is the attrs.xml to define the control custom attributes:

<resources>

    <declare-styleable name="CH2">
        <attr name="textText" format="string" />
    </declare-styleable>

    <declare-styleable name="CH3">
        <attr name="textFex" format="string" />
    </declare-styleable>

</resources>

This is the control CH2.java which ia in subspackage and does not work:

package com.myapp.controls;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

public class CH2 extends LinearLayout {

    private TextView textView;

    public CH2(Context context) throws Exception {
        super(context);
        init(context, null);
    }

    public CH2(Context context, AttributeSet attrs) throws Exception {
        super(context, attrs);
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs) throws Exception {

        this.setOrientation(LinearLayout.VERTICAL);

        LayoutInflater layoutInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        layoutInflater.inflate(com.myapp.R.layout.category_header, this, true);

        View v = findViewById(com.myapp.R.id.chText);
        this.textView = (TextView)v;

        if (attrs != null) {
            TypedArray a = getContext().obtainStyledAttributes(attrs, com.myapp.R.styleable.CH2);

            String text = a.getString(com.myapp.R.styleable.CH2_textText);
            this.textView.setText(text != null ? text : "<NULL!>");

            a.recycle();        
        }
    }
}

This is CH3.java which works:

package com.myapp;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

public class CH3 extends LinearLayout {

    private TextView textView;

    public CH3(Context context) throws Exception {
        super(context);
        init(context, null);
    }

    public CH3(Context context, AttributeSet attrs) throws Exception {
        super(context, attrs);
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs) throws Exception {

        this.setOrientation(LinearLayout.VERTICAL);

        LayoutInflater layoutInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        layoutInflater.inflate(com.myapp.R.layout.category_header, this, true);

        View v = findViewById(com.myapp.R.id.chText);
        this.textView = (TextView)v;

        if (attrs != null) {
            TypedArray a = getContext().obtainStyledAttributes(attrs, com.myapp.R.styleable.CH3);

            String text = a.getString(com.myapp.R.styleable.CH3_textFex);
            this.textView.setText(text != null ? text : "<NULL!>");

            a.recycle();        
        }
    }
}

Both sources use the same category_header.xml. The layout is loaded without problem. I can use both like this:

<com.myapp.controls.CH2
    android:id="@+id/cH1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >
    myns:textText="Test 1" >
</com.myapp.controls.CH2>

<com.myapp.CH3
    android:id="@+id/cH2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" 
    myns:textFex="Test 2"
    >
</com.myapp.CH3>

How can I make CH2 work? Or is it impossible to use another package?

Sidequest: Can I make both controls to use the same XML attribute textText or will they always have to use different attributes? Or can the declareable-style name be different from the components name?

---

Another approach with a new declare-styleable:

<declare-styleable name="controls.CH2">
    <attr name="textText" format="string" />
</declare-styleable>

But it does not seem to be usable. XML view always says Unexpected text found in layout file:, regardless how I use CH2:

xmlns:myns="http://schemas.android.com/apk/res/com.myapp"
xmlns:mynsc="http://schemas.android.com/apk/res/com.myapp.controls"
...
<com.myapp.controls.CH2
    android:id="@+id/cH1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >
    mynsc:textText="TestTestTest" 
    >        
</com.myapp.controls.CH2>

or

xmlns:myns="http://schemas.android.com/apk/res/com.myapp"
...
<com.myapp.controls.CH2
    android:id="@+id/cH1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >
    myns.controls:textText="TestTestTest" 
    >        
</com.myapp.controls.CH2>

Answer 1

I just went back to my own attribute files and there’s no reference anywhere to the very deep sub-package where my layout lives… as a side note, you can have multiple elements use the same attribute if you do this in your attrs file:

<resources>
    <attr name="textText" format="string"/>

    <declare-styleable name="CH2">
        <attr name="textText" />
    </declare-styleable>

    <declare-styleable name="CH3">
        <attr name="textText" />
    </declare-styleable>

</resources>

My study of the android source code shows a few examples where they do exactly what you’re describing, where they have a single custom attribute file pointing to view classes in different packages. The only glaring difference I saw was that the Views were declared in layout like this:

<view
  class="com.myapp.controls.CH2"
  android:id="@+id/cH1"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" >
  myns:textText="Test 1" >
</view>

<view
  class="com.myapp.CH3"
  android:id="@+id/cH2"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" 
  myns:textFex="Test 2"
>
</view>

I honestly couldn’t tell you why that would make a difference… but every time they need custom attributes that is the format used