Develop Reference

Android: Is there any specific place on the document to find explicit XML reference?

Android documentation for XML is too hard to find. Whatever I get is all Java related documents. I am a newbie to Android and trying to find XML references for Views and Widgets. For now, I am searching for Checkbox but it I am struggling to get XML reference every time for any component.
Can anyone help me to learn how to find and use the reference documents especially for XML and its attributes?
Million thanks.

The XML attributes are referred;
The CheckBox is created from inheriting CompoundButton, TextView etc.
Each view has its own XML attributes. So for CheckBox all the inherited values are applicable. For instance ChackBox has Button bahaviour, TextBox behaviour etc. Hence all above apply for the CheckBox. So if you want to add Button related behavior of CheckBox refer above 'Button Attributes'. If you want to add Text related behavior of CheckBox refer above 'TextView Attributes' etc.
Also refer https://developer.android.com/reference/android/R.styleable
Sample layout xml as follows;
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout android:id="#+id/llMainFill"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="bottom"
android:orientation="vertical">
<ListView android:id="#+id/lvLog"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="invisible" />
</LinearLayout>
</LinearLayout>

How to use a custom view in layout xml

I have made a custom view that I'm setting inside the onCreate() method in the Main Activity.
Like this:
compassView = new CompassView(this);
setContentView(compassView);
My question is. How do I reference the view in xml, so I can put it inside a linearlayout together with other controls?

Assuming your CompassView is a class which is placed in the Package called ,
com.android.sample
Create a XML like this,
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<com.android.sample.CompassView
android:id="#+id/compassview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>
And now as usual, setContentView(R.layout.xmlname); in your onCreate().
And compassView = (CompassView)findViewbyId(R.id.compassview);

setContentView("here put your xml layout")
In .xml layout just simple add ur View:
<com.example.widget.CompassView
android:id="#+id/..."
style="#style/..." >
</com.example.widget.CompassView>

First of all, you must override any constructor of your superclass. If you don't do that you will get a run time error and you activity will never be opened. Then you should use the fully qualified class name like this:
<your_package_name.your_class_name
android:id="#+id/mycompass"
your attributes here
...
/>

You will have to add your custom view In your xml file, something like this:
<yourpackagename.yourCustomViewClass
android:id="#+id/myCustomView"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
After this, you can access this view through its id, like you would have done for any other View

Declaratively defining fragments inside ViewPager

I have 5 unique pages of xml that are fairly complex. I want to put the 5 pages inside a ViewPager. All of the samples I can find simply put identical contents in each page via code. I want to declaratively define the xml in the viewpager like the xml pasted below. But this does not work - the app stops with this xml.
If I can't declaratively define it, then can I load individual xml pages into the viewpager? I can find no examples that do this.
thanks,
Gary Blakely
<?xml version="1.0" encoding="utf-8"?>
<fragment >
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ImageView android:layout_width="match_parent"
android:layout_height="match_parent" android:id="#+id/imageView1"
android:src="#drawable/flashright" android:adjustViewBounds="true" android:scaleType="fitXY">
</ImageView>
</LinearLayout>
</fragment>
<fragment >
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ImageView android:layout_width="match_parent"
android:layout_height="match_parent" android:id="#+id/imageView1"
android:src="#drawable/flashleft" android:adjustViewBounds="true" android:scaleType="fitXY">
</ImageView>
</LinearLayout>
</fragment>

If I follow, you want to declare everything in XML and avoid any programmatic initialization from within your Activity containing the ViewPager. The only way I can think of doing this would be to define 3 different Fragment classes which reference 3 different xml layouts. You could then embed them in your above xml, replacing each <Fragment> element with <FragmentX> <FragmentY> <FragmentZ> etc. Personally, I would rather write 3 xml layouts and create a single Fragment implementation that takes a single int argument to designate which layout to load, and then do the small amount of programmatic initialization necessary to make such a solution work. The rationale being that there is less duplicated code.
EDIT:
Another approach that might more fully address your requirements is to replace your <Fragment> tags with <Layout> tags and give them id's. Then in your Activity code, store refs to them, remove them from the View in onCreate() and finally add each of the stored references into programmatically created instances of Fragment which you then add to your ViewPager. Very ugly but thats the only way I know of to declaratively define everything in XML. You'll still have the problem that its not clear from the XML that these elements are nested within a ViewPager so personally I don't see the point. ListView and ListFragment operate with the same kind of implicit association though so its not unprecedented.

How to share a view across various activities

Is there any way to share the same object of the View across various activities? For example myApp has 4 activities, and every activity shows a Logo at the top of the screen. Now each activity will initiate 4 copies of the same Logo. So is there any way to get around this? And if 3 out of 4 share the same logo?

I can't say that it is completely impossible for you to do that. What I can say with almost certainty is that you should not attempt it or expect anything good to happen if you do manage it. Don't fight the framework, let it work for you. If the duplication is that much of an issue you create an abstract class that your Activities inherit from.
Also, since View's maintain a reference to the Context they were created in. If you did manage to pass a View from one Activity to another you would be creating a memory leak. Since the View would hold a reference to the old Activity via the Context it was created in.

Use seperate layout to make your logo.
Ex: title.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:background="#drawable/headercon" >
<ImageView
android:id="#+id/headerView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="centerInside"
android:src="#drawable/header" />
</LinearLayout>
This layout can be included in any other layout by using include tag
Ex:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
...
<include layout="#layout/title" />
...
</RelativeLayout>

How to implement master and child page like Activity in Android?

I want to place a common banner and menu on each Activity with footer too.
Can anyone guide me how can I implement master and child page like asp.net in Android???
Any help would be appreciated.

You could have each of your Activities extend a common base class which has a onCreateOptionsMenu method which inflates the menu from the same XML each time. Though as you can't have multiple inheritance, this may be tricky when you want to have plain activities and list activities, for example.
Another way would be to have a Util class where you have a method like setupMenu(Menu) which each of your Activities can call if you're doing some more complex menu setup.
In terms of the XML UI layout for each of your Activities, you can include a common banner by using the <include/> tag.

The solution was pretty easy.
You need to extends "Activity" Class,in onCreate function SetContentView to your base xml layout and also need to override setContentView in base Activity Class
For Example:
1.Create "base_layout.xml" with the below code
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="#000000"
android:padding="15dp" >
<LinearLayout android:orientation="horizontal" android:background="#000000"
android:layout_width="fill_parent" android:layout_height="wrap_content"
android:minHeight="50dp" android:paddingLeft="10dp">
<ImageView android:layout_width="wrap_content" android:id="#+id/ImageView01"
android:adjustViewBounds="true" android:layout_height="wrap_content"
android:scaleType="fitCenter" android:maxHeight="50dp" />
</LinearLayout>
<LinearLayout android:id="#+id/linBase"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</LinearLayout>
</LinearLayout>
2.Create "BaseActivity.java"
public class BaseActivity extends Activity {
ImageView image;
LinearLayout linBase;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.base_layout);
linBase = (LinearLayout)findViewById(R.id.linBase);
}
#Override
public void setContentView(int id) {
LayoutInflater inflater = (LayoutInflater)getBaseContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(id, linBase);
}
}
and
public class SomeActivity extends BaseActivity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.some_layout);
//rest of code
}
}
The only thing I noticed so far was that when requesting a progress bar (requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS)) this needs to be done before calling super.onCreate. I think this is because nothing can be drawn yet before calling this function.
This worked great for me and hopefully you will find this useful in your own coding.

I've had the same problem and solved it using ActivityGroup.
I suppose that menu items will move user to another activity, so with the same menu in every activity closing application with BACK button can be almost impossible (after some time user will have to go back through all activities he had ever seen).
I haven't found any good tutorials in english so have written mine some time ago (it's somewhat too short and in polish only, but Google Tranlslated version should be understandable) check this
You can also check how the TabHost works

ViewStub is the solution
activity_masterpage.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ViewStub android:id="#+id/stub_content"
android:inflatedId="#+id/subTree"
android:layout_width="match_parent"
android:layout_height="match_parent" />
stub = (ViewStub) findViewById(R.id.stub_content);
stub.setLayoutResource(R.layout.content_layout);
stub.inflate();