关于Android布局文件

Question

I would like to know about custom layout xml files in Android. I came across a code block that tells

 <org.superboy.ui.OnlineShop xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/sp_title" 
    android:layout_width="fill_parent" 
    android:layout_height="38dip"
    android:gravity="center_horizontal"
    android:orientation="horizontal"
    android:background="@drawable/shop_background"
    >

There is a file called OnlineShop.java in the src/org/superboy/ui I did not understand about creating such layouts other than default layout files that we create for activities. Any help pointing to such layouts or advice.

Answer 1

You can create anything such as TextViews etc. through a class and extend TextView, and then in your XML layout just add an item like above. Here is an example of a ResizeableTextView I made and an XML layout.

Answer 2

You will see that the OnlineShop.java class will extend something like the following :

• ViewGroup
• View
• LinearLayout
• RelativeLayout ect.

These all are objects that can be used in your xml file as a View . We call them custom Views .

You create custom Views when you have a specification in your app that cannot be handled by the standard View controls that Android provided (which will not be often because the default View controls are very versatile).

You can go read up on it here

Hope this helps

Answer 3

You must make sure that your OnlineShop.java file resides in which package, if your java file resides in your.project.package then you must change your layout file as

<your.project.package.OnlineShop xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/sp_title" 
android:layout_width="fill_parent" 
android:layout_height="38dip"
android:gravity="center_horizontal"
android:orientation="horizontal"
android:background="@drawable/shop_background"
>

Now compiler will refer your onlineShop.java file from your packages.

general information

when we place any XML code in our layout file let suppose bellow code

<TextView
android:id="@+id/textView"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

it looks our layout file from android.jar package which are included automatically in eclipse while making a new android project.

So if you make any custom layout then you have to create your own java class extending from any view or viewgroup in your own package and it should be declared in your XML file mentioning your package see my above code

Hope this helps :)